University of Ghana http://ugspace.ug.edu.gh USING BIOCHAR TO REDUCE LEACHING AND ENHANCE NITROGEN UPTAKE IN TWO GHANAIAN SOILS BY MICHAEL EGYIR (10507330) THIS THESIS IS SUBMITTED TO THE UNIVERSITY OF GHANA, LEGON IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE AWARD OF MPHIL SOIL SCIENCE DEGREE December, 2016 University of Ghana http://ugspace.ug.edu.gh DECLARATION I hereby declare that this thesis has been written by me and that it is an outcome of my own research. It has neither in whole nor portion been presented for another degree elsewhere. Research work of other researchers has been duly cited by references to the authors and any form of assistance received also acknowledged. ………………………………. Michael Egyir (Student) ………………………………. Dr. I.Y.D. Lawson (Major Supervisor) ……………………………… Dr. D.E. Dodor (Co-supervisor) i University of Ghana http://ugspace.ug.edu.gh DEDICATION I dedicate this piece of work to my children Michaelina and Stephannie. ii University of Ghana http://ugspace.ug.edu.gh ACKNOWLEDGEMENT I thank the all-knowing God for bringing me this far in education, glory be to his name. I wish to express my profound gratitude to my major supervisor Dr. Innocent Y. D. Lawson who never gave up on me during the trying moments of the research. I also acknowledge the tireless effort of Dr. Daniel Etsey Dodor my co-supervisor who also worked diligently to see to it that this work becomes a success. I am also grateful to Dr. Nartey for his useful contributions that have also contributed to the success of this research. My sincere appreciation goes to Miss Esther Ayetey Gyebiwa for been there for me when the going became tough. My last but not the least appreciation goes to the staff of the Department of Soil Science, University of Ghana for their assistance. iii University of Ghana http://ugspace.ug.edu.gh ABSTRACT In recent times the use of biochar as soil amendment has been proposed as one of the ways for reducing nitrogen leaching particularly in sandy soils because it has the potential to retain cations ° and anions. Three different biochar types (sawdust, rice husk and corn cob) pyrolysed at 400 C - + were tested in the laboratory to investigate their retention capacity for NO3 and NH4 . One hundred and fifty grams (150 g) of each biochar was packed into acrylic cylinders to create biochar column. The soluble cations in these biochar types were then leached out completely. Three nitrogen fertilizer solutions (ammonium sulphate, potassium nitrate and ammonium nitrate) prepared at 1.36 g N per litre were allowed to pass through the column and leachate - + collected to determine NO3 N and NH4 N. Results from the column leaching experiment showed - + that the sawdust biochar had superior retention capacity for NO3 and NH4 . This could be due to its relatively higher surface area when compared to the other biochar types. In another experiment in the screen house, the sawdust and rice husk biochar types were applied at 0, 20 and 40 t/ha and treated with different N sources (cow dung and ammonium sulphate; 265 N kg/ha) in two soils, Keta series (Quartzi Psamment) and Nyankpala series (Plinthic Acrisol) and maize was grown for five weeks. During the growth period the treated soils were leached at 14 and 28 days after planting to determine the quantity of available nitrogen (N) leached out. Biochar amendment of the soils reduced leaching of NO3-N and NH4-N, indicative of their ability to retain N in the soils. The amendment also enhanced dry matter production and N uptake by maize, therefore biochar amendment is recommended for reducing leaching. It was also recommended that the experiment should be conducted under field condition. iv University of Ghana http://ugspace.ug.edu.gh TABLE OF CONTENT DECLARATION ............................................................................................................................. i DEDICATION ................................................................................................................................ ii ACKNOWLEDGEMENT ............................................................................................................. iii ABSTRACT ................................................................................................................................... iv LIST OF TABLES ......................................................................................................................... ix LIST OF FIGURES ........................................................................................................................ x CHAPTER ONE ............................................................................................................................. 1 INTRODUCTION .......................................................................................................................... 1 CHAPTER TWO ............................................................................................................................ 4 LITERATURE REVIEW ............................................................................................................... 4 2.1 The role of nitrogen in crop production ................................................................................ 4 2.2 Leaching of nutrients in sandy soil ....................................................................................... 4 2.3 Effect of Nitrogen leaching in the environment .................................................................... 5 2.4 Origin of biochar ................................................................................................................... 7 2.5 Biochar as a material for soil amendment ............................................................................. 8 2.6 Effect of pyrolysis temperature on biochar ........................................................................... 8 2.7 Chemical composition and surface chemistry of biochar ................................................... 10 2.8 Biochar as source of plant nutrients .................................................................................... 11 v University of Ghana http://ugspace.ug.edu.gh 2.9 Effects of biochar on physical properties of the soil ........................................................... 14 2.9.1 Biochar effect on cation exchange capacity of the soil ................................................ 16 2.9.2 Biochar effect on soil pH .............................................................................................. 17 2.9.3 Effect of biochar on nitrogen leaching in soil .............................................................. 18 2.9.4 Biochar effect on nutrients uptake and dry matter yield of maize ................................ 20 2.9.5 Maize ............................................................................................................................ 21 CHAPTER THREE ...................................................................................................................... 22 MATERIALS AND METHODS .................................................................................................. 22 3.1 Soils used............................................................................................................................. 22 3.2 Characterization of soil ....................................................................................................... 23 3.2.1 Particle size analysis ..................................................................................................... 23 3.2.2 Bulk density (ρb) determination ................................................................................... 24 3.2.3 Determination of soil pH water (1:1) ........................................................................... 24 3.2.4 Determination of pH CaCl2 (1:2).................................................................................. 25 3.2.5 Determination of organic carbon .................................................................................. 25 3.2.6 Determination of available nitrogen in the soil ............................................................ 26 3.2.7 Determination of total nitrogen in the soil.................................................................... 27 3.2.8 Determination of available phosphorus ........................................................................ 28 3.2.9 Exchangeable bases and cation exchange capacity. ..................................................... 29 3.3.0 Exchangeable bases determination ............................................................................... 29 vi University of Ghana http://ugspace.ug.edu.gh 3.3.1 Cation Exchange Capacity............................................................................................ 30 3.4 Biochar types used .............................................................................................................. 31 3.5 Cowdung used ..................................................................................................................... 32 3.6 Laboratory experiment ........................................................................................................ 32 3.6.1 Leaching of water soluble basic cations and phosphorus ............................................. 32 3.6.2 Retention of nitrogen .................................................................................................... 34 3.7 Plant culture experiments .................................................................................................... 35 CHAPTER FOUR ......................................................................................................................... 37 RESULTS AND DISCUSSION ................................................................................................... 38 4.1 Soil characteristics............................................................................................................... 38 4.2 Some physical and chemical properties of the biochar types.............................................. 41 4.3 Laboratory column leaching experiment ............................................................................. 42 4.3.1 Leaching of water soluble ions in the biochar samples ................................................ 42 4.3.2 Nitrogen retention ......................................................................................................... 43 4.4 Amount of ammonium in leachate (First Planting) ............................................................. 45 4.5 Amount of ammonium in leachate (Second Planting) ........................................................ 47 4.6 Amount of nitrate in leachate .............................................................................................. 49 4.7 Shoot and root dry weights of maize ................................................................................... 52 4.8 Nitrogen uptake in maize .................................................................................................... 56 4.9 Available N content of residual soil after planting ............................................................. 58 vii University of Ghana http://ugspace.ug.edu.gh 4.9.1 Residual soils pH .......................................................................................................... 61 CHAPTER SIX ............................................................................................................................. 64 CONCLUSION AND RECOMMENDATION ............................................................................ 64 REFERENCE ................................................................................................................................ 65 APPENDICES .............................................................................................................................. 92 viii University of Ghana http://ugspace.ug.edu.gh LIST OF TABLES Table 1: Treatments ...................................................................................................................... 36 Table 2: Physical and chemical properties of the soils used ......................................................... 39 Table 3: Some physico-chemical properties of the biochar used ................................................. 42 Table 4: Some water soluble ions in the biochar .......................................................................... 43 Table 5: Amount of NH4 –N and NO3 –N retained by biochar ..................................................... 44 Table 6: Amount of NH4-N leached (first planting) ..................................................................... 46 Table 7: Amount of NH4-N leached (second planting) ................................................................ 48 Table 8: Amount of NO3-N leached (first planting) ..................................................................... 50 Table 9: Amount of NO3-N leached (Second planting) ................................................................ 51 Table 10: Concentration in maize after harvest ............................................................................ 55 Table 11: Nitrogen uptake in maize .............................................................................................. 57 Table 12: Residual soil available N (1st planting) ........................................................................ 59 nd Table 13: Residual soil available N (2 planting) ........................................................................ 60 st Table 14: pH of residual soils after 1 planting ............................................................................ 62 nd Table 15: pH of residual soils after 2 planting ........................................................................... 63 ix University of Ghana http://ugspace.ug.edu.gh LIST OF FIGURES Figure 1. Set-up for leaching of soluble cations and phosphorus ................................................. 33 st Figure 2: Shoot dry weight of maize (1 planting) ....................................................................... 52 st Figure 3: Root dry weight of maize (1 planting)......................................................................... 53 nd Figure 4: Shoot dry weight of maize (2 planting) ...................................................................... 53 nd Figure 5: Roots dry weight of maize (2 planting). ..................................................................... 54 x University of Ghana http://ugspace.ug.edu.gh CHAPTER ONE INTRODUCTION Nitrogen (N) is one of the nutrients that limit crop growth, especially in sandy soils and soils with low organic matter (OM) content. It is needed for the sustenance of the global agricultural production and it also has high essence on crop yield (Fan and Li, 2009; Leip et al., 2011). Most soils in Africa are low in N due to intensive weathering. When N fertilizers are applied, about 50% to 70% is lost through combination of factors like leaching, erosion, denitrification and microbial incorporation of the N into their biomass (McAllister et al., 2012). Therefore application of inorganic N fertilizers does not always translate into yield (Jaynes et al., 2001). - Leaching of nitrogen is one of the most common ways through which nitrogen especially NO3 is lost from the soil system, with the situation being severe in light textured soils and under heavy rainfall (Razzaque and Hannafi, 2005). When fertilizers are applied in excess in agricultural fields, it causes the release of nutrients like N and phosphorus (P) from the agricultural fields into water bodies (Laid et al., 2010). Applying N fertilizers in soluble form to sandy soils cause leaching of N which may pollute underground water (Paramasivan and Alva, 2008). This has subsequent effect on nutrients availability in the soil for plant uptake. Leaching of plant nutrients occurs when dissolved N in applied fertilizers moves downwards with percolating water within the soil profile. This is a crucial aspect of nutrients recycling in agriculture (Brady and Weil, 2008) and accounts for up to 80% loss of N in fertilizer applied to the soil. According to Lehman and Schroth (2003), leaching of N may significantly contribute to negative N balances in agricultural systems. Sandy soils and ferrallitic soils with low activity clays are particularly most prone to nutrients leaching. These soils have high infiltration rates, low nutrient 1 University of Ghana http://ugspace.ug.edu.gh retention capacity, low OM and high water conductivity which affect nutrients uptake by plants, fertilizer use efficiency and yield (Sitthaphanit et al., 2009; Zotarelli et al., 2007). This makes such soils inherently infertile and relatively unproductive (Yao et al., 2012). In Ghana cultivation of maize is mostly done in the transitional, coastal and guinea savanna zones because it is a staple for the people within these zones. In an attempt to sustain the fertility in the soils, farmers in these agro ecological zones apply large quantities of fertilizers especially N containing fertilizers. The applied N fertilizers leach under heavy rainfall resulting in environmental pollution and increase cost of production for the farmer. The use of organic fertilizers such as manure and planting of leguminous cover crops has been used in an attempt to limit the leaching of N in sandy soils in Ghana but the effect of these measures are short lived. The use of nitrification inhibitors and other control-released fertilizers had also been tried elsewhere (Baligar et al., 2001: Di and Cameron, 2002). In recent times the use of biochar has been proposed as one of the ways for reducing leaching in agriculture, because it has the capacity to improve the retention of cations and anions in soils (Major et al., 2009). According to Lehman and Joseph (2009), Maesek et al. (2011) and Kuppusamy et al. (2016), biochar addition to the soil is an evolving technology which has the potential to enhance food security whiles sequestering carbon to combat climate change. Biochar is a carbon rich material produced when biomass is heated under relatively low temperature < 700°C in the absence of oxygen (Lehman and Joseph, 2006). Biochar has increased negative - charged functional groups like carboxylates, positive charge sites and high surface area (Lehman et al., 2003; Laing et al., 2006). Therefore when applied to 2 University of Ghana http://ugspace.ug.edu.gh + - the soil it improves the adsorption of NH4 and NO3 and hence prevents their leaching in the soil profile (Chintala et al., 2013). - Economic considerations on how to manage NO3 in agricultural system concentrate on efforts to enhance N utilization and reduce cost of N inputs. Nitrogen management aims to balance N uptake with crop requirements and minimize leaching of N during rainfall (Zhaohui et al., 2012). Biochar has shown the ability to minimize loss of inorganic N from inorganic and organic sources in sandy soil (Lehman et al., 2009). However, little work has been done on biochar reducing leaching of nitrogen in Ghanaian soils. Therefore, this research seeks to investigate the influence of biochar amendment in sandy soils on leaching of N as the main objectives. The specific objectives of this research are to; - + (1) Identify biochar type from different feedstocks with better retention for NO3 and NH4 . (2) Investigate the ability of biochar to reduce leaching and enhance N uptake by maize. (3) Investigate the residual effects of biochar amendment on N leaching, growth of maize and N uptake. 3 University of Ghana http://ugspace.ug.edu.gh CHAPTER TWO LITERATURE REVIEW 2.1 The role of nitrogen in crop production Nitrogen is essential to life because all living things possess considerable amount of nitrogen. Nitrogen is an integral part of the DNA molecule. Among plant nutrients, nitrogen has the most complex behavior in soil. Nitrogen (N) is an essential input in crop production, but is inadequate in soils of the world, making it one of the nutrients that limit crop growth and yield, especially in sandy soils and soils with low organic matter content. It is required in increasing crop yield needed to feed the world‟s population (Fan and Li, 2009; Leip et al., 2011). The nitrogen content of most soils in Africa and the tropics is low, because about 50% to 75% of N applied to the soil in the form of fertilizer is lost through combination of factors like leaching, erosion, denitrification and microbial incorporation of the N into their biomass, sorption and volatilization which renders the applied N inaccessible to the plants roots (McAllister et al., 2012). Therefore application of inorganic N in fertilizers does not always translate into yield (Jaynes et al., 2001). 2.2 Leaching of nutrients in sandy soil Leaching of nutrients is one of the common ways through which applied N is lost from the soil systems (Lehmann and Schroth, 2003) and is an essential component of nutrients cycling in agriculture (Brady and Weil, 2008). Nutrient loss through leaching is unavoidable in high rainfall areas (Widowati and Asnah, 2014). Leaching occurs when dissolved nutrients move downwards with percolating water within the soil profile. Nutrients held onto particles and colloidal surfaces can also be moved away from the reach of plant roots through facilitated transport (Lehmann et 4 University of Ghana http://ugspace.ug.edu.gh al., 2004). Subsoil acidity restricts the rooting depth of sensitive plants (Lehmann and Schroth, 2003) and together with poor water quality causes leaching of nutrients (Jalali and Merrikhpour, 2006), which can hasten nutrients depletion, soil acidity and increase fertilizer cost to farmers (Yao et al., 2012). Leaching of dissolved anions in soil solution must be accompanied by leaching of cations in order to maintain electro-neutrality. As such the loss of anion like nitrate from applied N fertilizer must occur with leaching of cations like calcium (Ca), magnesium (Mg) and potassium (K) (Lehmann et al., 2004). 2.3 Effect of Nitrogen leaching in the environment Excessive application of fertilizers on agricultural fields can release nitrogen (N) and phosphorus (P) into aquatic systems (Attiq-ur-Rehman, 2011; Irshad et al., 2012) which may result in contamination of underground water, eutrophication and overproduction of photosynthetic aquatic microbes in fresh water and marine ecosystems (Havlin et al., 1999, Karaca et al., 2004). This phenomenon significantly contributes to negative nitrogen imbalances in agricultural systems (Lehman and Schroth, 2003). Species community structure, diversity, changes and functioning of terrestrial, freshwater and marine ecosystems are also directly affected by reactive nitrogen (Matson et al., 1997; Vitousek et al., 1997; Ribaudo et al., 2011). In an experiment by Irshad et al. (2014), they observed that maximizing nitrogen use efficiency on sandy soil is crucial in reducing ground water contamination and increasing economic yield. According to Knox and Moody (1991), actual leaching of nitrogen depends on the nitrogen source and its application rate. Leaching risk of nutrient increases with its mobility in the soil, 5 University of Ghana http://ugspace.ug.edu.gh nitrate is very mobile in the soil and it is therefore easily leached under heavy precipitation and + high application rate because of its low interaction with the negatively charge soil matrix. NH4 is readily immobilized by soil microorganisms and easily adsorbed by the negative charges on the soil (Schroth et al., 1999; Havlin et al., 1999). According to Burgo et al. (2006), leaching of nitrate from soils amended with organic materials depends on the application rate, time of application, amount of water applied, soil type and plant uptake. Nitrate leaching results from excessive irrigation and fertilizer use therefore nitrate leaching from fertilizers into ground water can be minimized by applying nitrogen fertilizers during active growth phase of crops (Hu et al., 2007) and also by improving fertilizer use efficiency through proper irrigation management techniques (Shresda et al., 2010; Zotarelli - etal., 2006). It is difficult to coordinate the control of NO3 leaching and economic benefit of - NO3 during the active growth period of crops. Therefore, it is imperative to nutrients managers to devise reliable techniques to minimize nitrate leaching (Zhang et al., 2012). Ribando et al. (2011) prescribed several measures such as improved management of nitrogen fertilizers and application of animal manure as means of enhancing overall nitrogen use efficiency (NUE) in order to decrease the loss of reactive nitrogen to the environment while sustaining crops yields. In an experiment by Nakamura et al. (2004) to assess root zone nitrogen leaching as affected by irrigation and nutrient practices, they observed that splitting the application of N fertilizer into two was able to reduce the amount of N leached by one-third compared to the lump application of the N fertilizer. They therefore, suggested that N fertilizer application should be done in split form during single cropping period in order to minimize leaching of NO3- N into groundwater. 6 University of Ghana http://ugspace.ug.edu.gh Nyanmangara et al. (2003) reported that leaching of nitrate from sole manure application is relatively low compared to combination of manure and inorganic fertilizer. The use of strategies such as nitrification inhibitors, slow and controlled-release fertilizers can be employed to reduce leaching of N in soil (Baligar et al., 2001; Di and Cameron, 2002). In recent times one of the proposed ways for reducing leaching in agriculture is by use of biochar, which has shown to improve the retention of cations and anions in leached soils (Major et al., 2009). 2.4 Origin of biochar Amazonian Indians started using biochar about 1000 years ago to produce terra preta soils which remained more fertile than the surrounding soil (Lehman et al., 2006). They developed the terra preta by adding large quantities of charcoal to the poor soils of the rainforest to enhance their fertility (Yu et al., 2013). According to Gul et al. (2015) the enhanced productivity of terra preta soils amended with biochar compared to unamended oxisols has created world-wide interest in applying biochar to agricultural soils. The terra preta soils that regularly receive biochar and other organic amendment have higher pH, high nutrients content, larger and diverse microbial population than unamended oxisols (Germano et al., 2012; Taketani et al., 2013; Gul et al., 2015). Biochar is a carbon rich material produced when biomass is heated under relatively low temperature < 700°C in the absence of oxygen. According to Hale et al. (2013), one unexplored avenue to increase nutrients availability in impoverished soils is the addition of biochar, but biochar did not receive the deserved attention until the publication in Nature article″ Putting the carbon back; Black is the new green″ (Marris, 2006). 7 University of Ghana http://ugspace.ug.edu.gh 2.5 Biochar as a material for soil amendment Although in recent times biochar production has received much attention, the mechanism of its formation is still unclear and structure of biochar still remains uncertain (Ye et al., 2015). Biochar is usually considered as highly efficient and cheaper adsorbent material which is environmentally friendly (Chen et al., 2008) which has now provided a new means of sequestering carbon and enhancing soil fertility (Beesley et al., 2011). It is an evolving technology which has the potential to enhance food security whiles sequestering carbon (C) to combat climate change (Lehman and Joseph, 2009; Masek et al., 2011; Kuppusamy et al., 2016). Any form of organic material such as crop residues, forest by-product, urban yard waste, industrial by-product, manure and sewage sludge can be charred into biochar. Notwithstanding this it is not every organic waste that is suitable for producing biochar good for agricultural purposes. Because the physico-chemical properties of biochar are significantly influenced by the raw material and pyrolysis temperature (Ronsse et al., 2013) which subsequently affects sorption ability of the biochar produced (Ogbonnaya and Semple, 2013). According to Gwenzi et al. (2015) biochar can be applied as soil amendment together with inorganic fertilizer without any negative effect on plant growth. 2.6 Effect of pyrolysis temperature on biochar According to Demirbas et al. (2004) pyrolysis of biochar involves three stages; first step involves loss of volatiles; formation of primary biochar occurs during the second step and the third step involves decomposition of primary biochar at very slow rate and chemical rearrangement to form carbon-rich residual solid (biochar). In an experiment by Sun et al. (2014) 8 University of Ghana http://ugspace.ug.edu.gh to assess the effect of type of feedstock, production method and pyrolysis temperature on biochar and hydrochar, they observed that biochar yield decreased as the pyrolysis temperature increased. They attributed it to the decomposition of organic matter as temperature increases. Higher pyrolysis temperature increases stability, aromaticity and strengthens bonds of biochar material (Zimmerman, 2009). Pyrolysis temperature higher than 400°C can cause loss of aliphatic-C moieties and a centralization of C compound to poly-condensed aromatic-C type which significantly affects the stability of biochar C in soil (Novak et al., 2010). According to Uchimiya et al. (2011) the charring temperature of biochar can influence the type of functional groups on its surface and its heavy metal sequestration capacity in soil. Sun et al. (2014) also observed that the pyrolysis temperature of biochar affects its elemental compositon. Biochar charred at lower temperatures may have better adsorption ability (Liang et al., 2006) due to increased negatively-charged functional groups like carboxylates on their surfaces. Chemical composition of biochar pyrolysed at lower temperature is closer to the chemical composition of the original feed stock whiles those biochar charred at higher temperature has its chemical composition closer to that of graphite (Masiello, 2004). According to Parakayastha et al. (2016) biochar from crop residues pyrolysed at higher temperature is more stable than those pyrolysed at lower temperature. Biochar charred at lower temperature has higher content of volatile matter such as bound carboxylic acid, phenol, ketone and aldehyde functional groups but has lower fixed carbon and ash compared to biochar charred at higher temperature (Bourke et al., 2007). Yuan et al. (2011) observed that nitrogen (N) content of sewage sludge biochar decreases as the pyrolysis temperature is increased. Nutrients such as P, K and Ca, surface area, pH, carbon: nitrogen (C: N) ratio and carbon: oxygen (C: O) ratio of biochar increases as pyrolysis temperature increases (Novak et al., 2013; Gul et al., 2015). Higher pyrolysis temperature 9 University of Ghana http://ugspace.ug.edu.gh generally reduces H: C and O: C ratios but increases the alkalinity, ash content, pH and C: N of the biochar (Yuan et al., 2011). Therefore, biochar charred under different temperatures need to be characterized in order to determine its agronomic usefulness (Wang et al., 2015). 2.7 Chemical composition and surface chemistry of biochar Biochar is heterogeneous in nature and has both stable and labile constituents (Sohi et al., 2009). Biochar feedstock influences its physical and chemical properties which determine its behavior and uses (Brown, 2009; Demiebas, 2004). It is stable and recalcitrant when applied in the soil due to its high carbon content and aromaticity (Sohi et al., 2010). The chemical composition of biochar dictates its surface chemistry and reaction with organic and inorganic compounds within the environment. The outer surface and pore surface of biochar is occupied by aldehyde – (C=O) H, carboxyl–(C=O) and OH (Zwieten et al., 2009). The characteristics of biochar ranges from basic to acidic, hydrophobic to hydrophilic, because the functional groups on the material can accept electrons or donate electrons (Amonette and Joseph, 2009). Biochar materials are porous with high surface area and CEC (Demirbas 2004; McElligot, 2011;Kongthod et al., 2015) and when it stays longer in the soil, its surface undergoes oxidation which helps in improving the cation exchange capacity of the soil (Liang et al., 2006; Chintala et al., 2015). There are also positive charge sites on biochar which gives anion exchange capacity to the material which can attract nitrate and phosphate ions (Chintala et al., 2015). According to Borchard et al. (2012), only biochar with hydrophilic surfaces can enhance nutrients retention, aggregation of particles and cation exchange capacity. Biochar can affect the 10 University of Ghana http://ugspace.ug.edu.gh nitrogen dynamics in soil by changing the rate of transformation processes (Clough and Condron 2010; Clough et al., 2013). 2.8 Biochar as source of plant nutrients Biochar is recalcitrant in nature and this increases its potential as soil amendment for longer term compared to most soil organic materials which easily degrade when added to the soil (Chanet al., 2007). The recalcitrant nature of biochar in soil and its resistance to loss through degradation, leaching and chemical oxidation is due to its aromatic structure, surface functionality and sorption properties of other minerals and organic compounds (Shrestha et al., 2010). According to Wang et al. (2007) biochar with high H: C and O: C ratio has higher number of functional groups which provide more chemical bonding with polar compounds. It is comparatively stable in most environments as charred materials and has residence time between 1000-1500 years (Glaser et al., 2010). According to Spoka (2010), the stability of biochar is based on its half – life and is determined by the O: C ratio. The half-life of biochar could be ˃ 1000 years when the O: C ratio is ˂ 0.2 with the half-life decreasing to ˂ 100 years when O: C ratio ˃ 0.6. Despite its recalcitrant nature biochar can be degraded biotically (microbial incorporation or oxidative respiration of C) and abiotically (chemical oxidation, photo oxidation or solubilization) (Major et al., 2010) to release the nutrients in it. Biochar characteristics alter with time in the soil, as a result of its oxidation and accumulation of + H from the soil solution during the first weeks of its addition. The level of changes in the biochar properties with time depends on the biochar source and climatic conditions (Heitkotter and Marschner, 2015, Chan et al.; 2008). 11 University of Ghana http://ugspace.ug.edu.gh According to Lehman et al. (2002) biochar can act as soil fertilizer when applied to the soil. The uses of biochar as soil amendment to enhance soil fertility and plant growth had received much research focus in recent time (Ibrahim et al., 2013). Biochar addition to soil can increase soil fertility and crop production; therefore it is beneficial to agricultural ecosystem just like any other organic material. Although the nutrients in biochar material originate from the feedstock, the amount of nutrients in the feedstock cannot be used as reliable assessment for the nutritive value of the biochar in crop production. Because during the charring process the proportion of individual elements mineralized, co-stabilized with C and volatilized are not equal (Angst and Sohi, 2013). The improvement in soil fertility when amended with biochar is due to increase in cation exchange capacity of the soil caused by biochar addition to the soil (Laing et al., 2006). Basso et al. (2012) reported that amending sandy soils with biochar increase availability of some nutrients and therefore should be considered as management alternative. Biochar material contains nutrients therefore when added to the soil can release basic cations such as K, Ca and Mg (Glaser et al., 2002). According to Wadowati and Asnah (2014) when -1 biochar is applied at rate of 30 t ha it can act as K fertilizer which is sufficient for meeting crop K requirement. There is great potential for enhancing the environmental and economic benefits of biochar by fortifying it with nitrogen (N) from both inorganic and organic sources (Clough et al., 2013). According to Zimmerman et al. (2011) biochar serves as source of easily mineralized C, N, P and micronutrients which helps in stimulating the mineralization of more refractory soil organic matter components. Biochar can act as reservoir of P for soils, large portion of the P in biochar exists in plant available form but the amount of P in the biochar material is determined by the feedstock and the 12 University of Ghana http://ugspace.ug.edu.gh pyrolysis conditions (Zhang et al., 2016). Charring of agricultural residue into biochar helps stabilize and retain the P contained in it and this helps to reduce the P mobility in the soil. Unlike other agricultural residues, the amount of P recycled by the biochar is relatively slow and reduces the amount of labile P applied to the soil. This provides lasting P source to the soil and help minimize potential loss of P from the soil system (Dai et al., 2016). Cui et al. (2011) reported that biochar amendment may enhance P availability to plants by reducing P adsorption on ferrihydrite in Oxisol. Accoring to Ma and Matsunaka (2013) biochar can be used as P source in soil with low P content. According to Gaskin et al. (2008), nitrogen from biochar might not be available for plant. Although the biochar material contains plant bioavailable nutrients, these constitute just small fraction of the total nutrients in biochar (Yuan et al., 2016). An improvement in plant growth when biochar is added to soil is suggested to be caused by biochar ability to influence changes in available nitrogen and phosphorus (Yao et al., 2012; Kongthod et al., 2015). Some biochars are also enriched with cationic elements like K, Ca and Mg due to high quantities of ash contained in them (Yuan et al., 2011; Butnan et al., 2016). Prendergast-Miller et al. (2014) reported that in biochar amended soil, plant root growth is stimulated when the roots absorb biochar constituents. According to Ren et al. (2015), plant root produce exudates which may affect sorption ability of biochar. Wu et al. (2011) noted that mallee wood biochar contain 15% - 20% calcium (Ca), 10% - 60% phosphorus (P) and 2% nitrogen (N) which can easily be leached with distilled water. According to Clough et al. (2013) recent studies has shown varied indirect effects of biochar on soil nitrogen (N) with potential effects for nitrogen cycling and plant nutrition. Yao et al. (2012) reported that adding biochar to the soil releases biochar associated P and transforms soil P into more available form for plant uptake. In microcosm study 13 University of Ghana http://ugspace.ug.edu.gh by Molner et al. (2016) in assessing biochar improvement on acidic sandy soil, they observed that application of grain husk biochar and paper fibre sludge biochar beneficially influenced available phosphorus and potassium. Biochar addition to the soil can also influence biogeochemical processes in the soil such as carbon (C) and Nitrogen cycling (Nelissen et al., 2012) which can induce immobilization of nitrogen (Zavalloni et al., 2011). The high surface charge density on biochar enables it to retain cations by cation exchange. The high surface area, internal porosity and existence of both polar and non-polar surface sites on biochar allow biochar to adsorb nutrients (Laid et al., 2010). Studies have shown that biochar may sorb and retain nutrients thereby enhancing soil nutrients availability to plants (Lehmann et al., 2011; Ventura et al., 2013). This can subsequently enhance fertilizer use efficiency (Zhao et al., 2014). 2.9 Effects of biochar on physical properties of the soil According to Mukherjee et al. (2014) the effects of biochar on field soil conditions is poorly understood. The effects of biochar on physical properties of the soil have not received much attention compared to its effect on chemical properties of the soil, despite the importance of enhanced soil physical properties in increasing crop production in sandy soil (Atkinson et al., 2010; Cornelissen et al., 2013). Studies on biochar have reported that its addition to the soil influences physical, chemical and biological properties of the soil (Laid et al., 2010; Lone et al., 2015) which hinges on the soil and erimental conditions (Liu et al., 2016). The texture of the soil determines the effect of biochar on its physical properties such as water retention, hydraulic conductivity and aggregate stability 14 University of Ghana http://ugspace.ug.edu.gh (Malnar et al., 2016). Soil porosity is an important soil characteristic influencing plant growth. Biochar application to the soil increases the overall porosity of the soil, but the extent of increase is determined by the biochar and soil types and where the biochar is applied (Herath et al., 2013). Biochar ability to enhance soil porosity could be attributed to its high porous nature (Mukherjee et al., 2013). When biochar is added to the soil it helps in decreasing the bulk density of the amended soil (Mukherjee et al., 2013) and bulk density decreases with high biochar application rate (Githinji, 2013). Decreased bulk density enhances plant roots extension and spreading of the plant roots within the soil medium (Laid et al., 2010). Application of biochar also indirectly enhances soil aggregation by providing refuge for soil microbes which secrete polysaccharides which glue soil colloidal particles together (Dorioz et al., 1993; Aslam et al., 2014). According to Yu et al. (2013) addition of biochar to the soil, has been suggested as a technique for enhancing soil water holding capacity but there are few quantitative studies on the efficiency of the biochar material in improving water retention. Biochar has high porosity which improves water retention in biochar amended soils. Singh et al. (2010) documented that this retains dissolved nutrients in water making them available for plants uptake. The enhancement in water retention is influenced by type of feed stock, soil type and biochar mixture rates (Singh et al., 2010). Zhan and You (2013) reported that biochar capacity to improve soil water holding capacity is influenced by the surface functional groups, total pore volume, porosity structure and specific surface area of the biochar material. According to Hardie et al. (2014) biochar possess higher proportion of hydrophilic micropores which can retain water, therefore when biochar is added to 15 University of Ghana http://ugspace.ug.edu.gh sandy soil it may enhance water holding capacity of the sandy soil. Addition of biochar to soil enhances plant available water which is one of the factors that hinders crop production (Basso et al., 2013). Biochar can increase both soil water holding capacity and available water content (Mukherjee and Lal, 2013; Obia et al., 2016). According to Amonette and Joseph (2009) addition of biochar to the soil can influence the soil structure, texture, porosity, particle size and density, oxygen content, water holding capacity, microbial and nutritional status of the soil within the rhizosphere. 2.9.1 Biochar effect on cation exchange capacity of the soil When biochar is added to the soil, its surface undergoes oxidation (Cheng et al., 2008) leading to higher CEC and charge density on the biochar material (Liang et al., 2006). The cation exchange capacity of biochar material increases as the biochar material ages in the soil (Laing et al. 2006). Biochar material has high surface area and porosity (Nigussie et al., 2012) therefore when added to soils with low CEC it can enhance the CEC of the soil (Van Zwieten et al., 2010). According to Mohamed et al. (2016), the high CEC of biochar material is caused by the presence of significant quantity of hydrophilic oxygen-containing groups like carboxylic and phenolic compounds with higher cation exchange capacity on biochar surface. Dume et al. (2016) also observed an increase in soil CEC following addition of biochar to the soil, and attributed the increase to inherent characteristics of the biochar feedstock. + Due to high CEC of biochar it can exchange cations such as NH4 with soil solution (Lehman et al., 2007). Mukhejee et al. (2014) documented that amending sandy and loamy soils with hardwood-derived biochar can effectively increase CEC by 1.5 times. 16 University of Ghana http://ugspace.ug.edu.gh 2.9.2 Biochar effect on soil pH The pH of biochar material is determined by the feedstock, pyrolysis temperature and duration of the pyrolysis process (Yuan et al., 2011). According to Molner et al. (2016), pH value of acidic sandy soil significantly increased with increased biochar application rate. Hass et al. (2012) reported that when biochar is added to the soil, the resultant increase or decrease in the soil pH depends on the soil and biochar properties. Liu and Zhang (2012) observed a decrease in pH value of alkaline soil when amended with biochar. They attributed the decrease to the combined effect of the basic cations in biochar and the soil carbonates to form partially soluble carbonates which affected the hydrolyzation of the carbonates leading to reduction in hydroxyl content of the soil. According to Cheng et al. (2008) biochar is reactive in nature therefore when added to an alkaline soil its surface undergoes oxidation through chemical and microbial activity to form acidic functional groups like carboxylic acid. The acidic functional groups can neutralize the alkalinity of the soil and decrease the pH of the alkaline soil (Brodowski et al., 2005). In quantitative review by Jeffrey et al. (2011) to assess the effects of biochar application to soil on crop productivity using meta-analysis, they observed positive effect of biochar on acidic, neutral pH soils, coarse and medium textured soils and attributed it to the liming effect of biochar on soil. Biochar can act as liming agent due to its alkaline nature, therefore when added to the soil it can reduce exchangeable acidity (Chan et al., 2008; Major et al., 2010). When biochar is incorporated in soil, it mineralized to release cations into solution (Keith et al., 2011; Zimmerman et al., 2011) which displaced exchangeable acidity and increased soil pH (Wang et al., 2013). According to Major et al. (2010) biochar can release great amount of 17 University of Ghana http://ugspace.ug.edu.gh 2+ 2+ exchangeable Ca and Mg in acid soil which neutralized the pH and improved yield of maize in oxisols. During the charring process of biochar, basic cations like Ca, K, Mg and silicon are formed from oxides and carbon, and when biochar is added to the soil, these oxides are released + + and they react with exchangeable Al and H and help in elevating soil pH (Novak et al., 2009). 2.9.3 Effect of biochar on nitrogen leaching in soil Nitrogen is one of the commonest elements occurring in nature and is the main nutrient involving in plant nutrition but excess of it poses threat to the environment (Adomaitis et al., 2008). Leaching of nitrogen (N) is the common way through which N contained in applied fertilizer is lost (Goulding, 2000). Nitrate leaching is one of the main problems associated with intensive agriculture (Beaudoin et al., 2005; Kanthle et al., 2016). Nitrogen (N) and Phosphorus (P) are plant nutrients that usually influence the quality of surface and underground water (Sparks, 2003). According to Lehman et al. (2004) about 80% of applied nitrogen (N) is lost from the root zone through leaching. Over reliance on chemical fertilizers and low supplementation with organic inputs has worsened the situation. Reducing nitrate leaching from agriculture fields can reduce nitrate economic loss to farmers and limit the effect of high loading of nitrate on ecological balance in water bodies (Kanthle et al., 2016). According to Yao et al. (2012) an alternate technology to reduce leaching in soil could be the application of biochar to the soil. Amending soil with biochar has been suggested as a reliable long-term measure for safeguarding surface and underground water quality against negative impact of nutrient leaching particularly nitrogen (Steiner et al., 2008). 18 University of Ghana http://ugspace.ug.edu.gh Studies have shown that, biochar due to its high surface area and surface charge, it can be used as environmental absorbent (Ahmad et al., 2014). It has been suggested that biochar ability to reduce N leaching is due to its high absorption potential because of elevated surface area and porosity of biochar materials (Liang et al., 2006; Van Zwieten et al., 2009; Zhao et al., 2015). Karanthanasis (1999) reported that the size of biochar particles can also determine its leaching reduction potential. The nitrogen retention in soil following biochar amendment can positively influence N uptake in crops and productivity (Steiner et al., 2008). Biochar addition to soil influences nutrient leaching through several mechanisms; increasing water retention in the rooting zone through direct binding or sorbing nutrients or by interacting with other soil constituents (Lehman et al., 2004). Emperical evidence confirms that biochar improves water and nutrients retention by enhancing electrostatic adsorption sites (Lehman et al., 2003). When biochar is added to the soil it increases soil aggregation which results in high water holding capacity which helps in enhancing nitrogen retention in the amended soil. Biochar ability to reduce leaching of nitrogen in the soil could also be attributed to its ability to increase the cation and anion exchange capacities of the soil (Yoo et al., 2014; Xu et al., 2016). According to Laing et al. (2006), the high surface charge of biochar enables biochar to hold + cations such NH4 by cation exchange. In an experiment by Lehmann et al. (2003) to measure nutrients leaching in soil biochar mixture using pot lysimeter in greenhouse, they noticed that biochar prepared from Manaus when mixed with typic Hapludox can reduce leaching of ammonium more than 60% over 40 days of cropping rice compared to the control soil without biochar amendment. According to Bai et al. (2015) biochar effect on nitrogen retention in field settings is mainly abiotic processes. 19 University of Ghana http://ugspace.ug.edu.gh 2.9.4 Biochar effect on nutrients uptake and dry matter yield of maize According to Taghizadel et al. (2012) recent evidence has indicated that nitrogen adsorbed by biochar is eventually made available for plants uptake. Nigussie et al. (2012) in assessing the effect of biochar application on soil properties and nutrients uptake of lettuce in chromium polluted soils, observed that N uptake in lettuce increased with increasing biochar rate and attributed the increase to biochar ability to enhance fertilizer use efficiency in soils especially soils with high leaching tendency. Applying biochar alone or in combination with organic material (vermicompost) to acidic sandy soil positively affect soil fertility, maize growth and yield and nutrient retention (Doran et al., 2015). Uzoma et al. (2011) reported an increase of 150% in maize dry matter yield in soils amended with biochar compared to unamended soil. In an experiment by Ma and Matsunaka (2013) to assess the impact of different size biochar derived from dairy cattle carcasses as an alternate P source and amendment in an acid soil. They observed that when biochar was applied as sole amendment or together with N fertilizer, it could significantly improve dry matter weight of shoot and roots of crops. They therefore concluded that irrespective of the size of biochar applied, dry matter of crops increased with elevated P rate. Applying biochar alone as soil amendment without fertilization will not increase dry matter yield (Chan, 2007) due to its low bio-availability (Zavalloni et al., 2011). Borchard et al. (2014) also noted that increasing the rate of biochar charred under slow pyrolysis conditions can decrease dry matter yield of plants. Nguyen (2008) also observed that the elevation in soil pH following biochar addition may result in decline in maize dry matter yield and attributed it to nutrients like phosphorus becoming unavailable as the soil pH is increased beyond 8.0 20 University of Ghana http://ugspace.ug.edu.gh 2.9.5 Maize Teosinte (Z. Mexicana) is generally accepted to be the ancestor of maize but there are varied opinions as to whether maize is the domesticated form of teosinite (Galinate, 1988). According to Gibson and Benson (2002) evidence suggested that cultivated maize resulted from natural crossings, first with gamagrass to yield teosinte followed by back crossing of teosinte with primitive maize to produce the modern races and is the most completely domesticated of all field crops. Maize scientifically known as Zea mays belongs to the family Graminae (poaceae). It is cultivated throughout the world and is a staple for larger proportion of the world‟s population (Canadian Food Inspection Agency, 1994). According to Chaudhry (1983) maize contains about 72% starch, 10% protein, 4.8% oil, 8.5% fibre, 3.0% sugar and 1.7% ash and forms an important component of animal feed (Khan et al., 2014). Currently about 594 million tons of maize is produced from 139 million hectares in the world FAOSTAT (2000). Maize is one of the most important cereal crops produced in Ghana but production levels are low because its cultivation is mostly done by peasant farmer in soils with low fertility status under rain fed condition (Adu, 1995; SARI, 1996; FAO, 2005). Maize is grown in both tropical and temperate climates but different varieties have adapted to ° different climatic zones, the mean daily temperature for maize cultivation should exceed 15 C (FAO, 2015). It survives best in well drained sandy loam soil with pH of 5.7 - 7.5 and average annual rainfall of 500 mm – 800 mm (FAO, 2005). According to Baloyi et al. (2014) maize has high demand for nutrients especially nitrogen. 21 University of Ghana http://ugspace.ug.edu.gh CHAPTER THREE MATERIALS AND METHODS 3.1 Soils used The soils used in the present study are Keta and Nyankpala series. The Keta series was sampled from Anloga, a town located in the Keta Municipality of the Volta Region of Ghana. The area is ° within the coastal savannah zone of Ghana and has mean temperature of 28 C mean annual rainfall of about 900 mm which is evenly spread over the year (Dickson and Benneh, 1995). The Keta series is classified as Quartzi Psamment according to Soil Taxonomy by Awadzi et al. (2008). According to Obeng (2000) the soil is developed on costal dunes and consists of yellowish, loose, coarse sand with fragments of shell, droughty in nature and inherently infertile. Although the Keta series has little agricultural prospect due its low fertility status, with heavy fertilization the soil has been used for intensive maize and vegetable production over the years (Obeng, 2000). The soil was sampled at the depth of 0-20 cm, transported to the laboratory, air dried, sieved through 2 mm sieve, analysed and used for the study. The Nyankpala series was sampled from Nyanpkala in Tolon- Kumbumgu District of Northern Region. Nyanpkala is in the guinea savannah zone of Ghana with unimodal rainfall pattern of 1000-1300 mm per annum and mean temperature of 32°C. The soil is classified as Plinthic acrisol according to USDA, soil taxonomy Ziblim et al. (2012). It is moderately shallow to deep concretionary, gravelly with medium texture overlying shale (Obeng, 2000). The soil was sampled at depth of 0-20 cm, transported to the laboratory, air dried and analysed. The two soils were sampled from cultivated fields. 22 University of Ghana http://ugspace.ug.edu.gh 3.2 Characterization of soil 3.2.1 Particle size analysis Forty grams (40 g) soil was weighed into plastic bottle and 100 mL of sodium hexametaphosphate or calgon solution added. The suspension was put on a mechanical shaker and shaken for 2 hrs after which it was transferred into sedimentation cylinder and distilled water added to 1000 mL mark. A plunger was inserted into the suspension, moved in upward and downward strokes to mix the suspension thoroughly. The suspension was left to stand on the bench for 5 mins, after which a hydrometer was lowered into it and the scale read at the top of the meniscus as the hydrometer reading for clay and silt. The suspension was left on the bench undisturbed for 5 hrs after which the hydrometer reading for only clay was taken. After the second reading had been taken, the suspension was poured out directly into a 47µm sieve from the sedimentation cylinder and the affluent collected into a container. The particles were obtained from the residues by agitating the residues by running tap water through it. The particles were transferred into a moisture can using a wash bottle and dried in an oven at a temperature of 105°C for 24 hrs. Based on the oven dry weight of the soil sample taken, the percentage sand, silt and clay fraction in the soil were calculated as follows: Clay (%) = × 100 Silt (%) = % (Clay + Silt) – Clay (%) Sand (%) = × 100 The textural classes were then determined by using textural triangle. 23 University of Ghana http://ugspace.ug.edu.gh 3.2.2 Bulk density (ρb) determination Bulk densities of the soils were determined by using the core method. A cylindrical metal core of known height and diameter was used to sample the soil by driving it into the soil by hitting it with mallet. The samples were taken out and the ends of the metal core were trimmed and covered. The soil samples were taken to the laboratory and dried in the oven at a temperature of 105°C for 24 hrs, after which the dry weights were determined. The weight of the empty metal core was also measured. Bulk density was calculated using the formula (Blake and Hartege, 1986). ρb = Ms/Vt Where Ms= mass of oven dry soil Vt = volume of soil in core sampler. 3.2.3 Determination of soil pH water (1:1) Ten grams (10 g) of soil were weighed into a beaker and 10 mL of distilled water was added to give a 1:1 (soil to water) ratio. The mixture was stirred several times for 30 mins and left to stand for 1hr to allow most of the clay particles in suspension to settle. Two different solutions of pH 4 and 7 were used to standardize the glass electrode pH meter-CG818, Schott Great. The electrode was then rinsed with distilled water, immersed into the partly settled suspension and the pH reading on the meter recorded. 24 University of Ghana http://ugspace.ug.edu.gh 3.2.4 Determination of pH CaCl2 (1:2) Ten grams (10 g) of soil were weighed into a beaker and 20 mL of CaCl2 solution was added to give it a 1:2 (soil to salt) ratio. The mixture was stirred several times for 30 mins and left to stand for 1hr to allow most of the clay particles in suspension to settle. Two different solutions of pH 4 and 7 were used to standardize the glass electrode pH meter-CG818, Schott Great. The electrode was then rinsed with distilled water and then immersed into the partly settled suspension and the pH reading on the meter recorded. 3.2.5 Determination of organic carbon The wet oxidation method of Walkley and Black (1934) modified by Allison (1965) was used to 2- determine organic carbon in the soil. The method involves the reduction of Cr2O7 ions by 2- organic matter and the unreduced Cr2O7 measured by titration with Ammonium Ferrous 2- Sulphate. The quantity of organic matter oxidized is calculated from the amount of Cr2O7 reduced. Half a gram (0.5 g) of finely ground soil that had been sieved through 0.5mm sieve was weighed in triplicate into 500 mL Erlenmeyer flasks. Ten millimeters (10 mL) of 1.0M (K2Cr2O7) was added to the soil followed by 200 mL of concentrated H2SO4. The flask was swirled to ensure that the solution comes into contact with the soil particles. After swirling it for some time it was allowed to stand for 30 mins. After 30 mins, 200 mL of distilled water was added followed by 5 mL of 85% orthophosphoric (H2PO4) acid, 2 mL of Barium diphenyl-4-suphonate indicator before titrating against 0.5 M acidified Ammonium Ferrous Sulphate from an orange colour to 25 University of Ghana http://ugspace.ug.edu.gh green end point. Organic matter content was calculated by multiplying percent organic carbon by the conventional factor of 1.33 using formula. %OC = Where %OC = Percent organic carbon V = Titre value (mL) N = Normality of Fe (NH4)2SO4 W = Weight of soil sample. 3.2.6 Determination of available nitrogen in the soil Five grams (5 g) of soil that had been sieved through 2 mm sieve was weighed into a 100 mL centrifuge bottle and 50 mL of 2M KCl solution added. The content of the bottle was placed in mechanical shaker and shaken for 30 mins, after which the suspension was filtered through Whatman No 42 filter paper into another container. Five milliliters (5 mL) of the filtrate was pipetted into micro Kjedahl digestion flask and 0.2 g of MgO was added. The flask was connected to a distillation apparatus and 30 mL of the distillate collected in 5 mL of 2% boric acid containing (methyl red-methylene blue indicator mixture). The distillate collected in the boric acid was titrated against 0.01 M HCl till a purplish end point was reached to determine + NH4 . One milliliter (1 mL) of sulphamic and 0.2 g of Devada′s alloy were added to remaining content of the flask and another distillate collected in a separate conical flask containing 5 mL of 2% 26 University of Ghana http://ugspace.ug.edu.gh boric acid containing methyl red-methylene blue indicator mixture. The distillate collected in the boric acid was back titrated against 0.01M HCl till a purplish end point was obtained to - + - determine NO3 . Concentrations of NH4 and NO3 in the soil were determined from the number of moles of HCl consumed in the back titrations. NH4-N mg/kg = NO3 – N mg/kg = Where M = Molarity of HCl V=Volume of HCl consumed in back titration V=Extraction volume of KCl 3.2.7 Determination of total nitrogen in the soil The total nitrogen in the soil was determined using the Kjedahl method. Half a gram (0.5 g) of soil that had been sieved through 2 mm sieve was weighed into 250 mL Kjedahl flask and a tablet of digestion accelerator (selenium catalyst) was added, followed by addition of 5 mL of concentrated H2SO4 acid. The mixture was digested till it became clear, after which the flask was allowed to cool. The mixture was transferred into 100 mL volumetric flask and made to volume with distilled water. An aliquot of 5 mL of the digest was taken to a Markham distillation apparatus. The mixture was distilled after adding 5 mL of NaOH. The distillate was collected in 5 mL of 2% boric acid (containing indicator methylene blue and methyl red mixture) in 50 mL 27 University of Ghana http://ugspace.ug.edu.gh Elenmeyer flask and then titrated against 0.01M HCl acid solution (Bremner, 1965). The percentage (%) total nitrogen was calculated as % N = × 100 3.2.8 Determination of available phosphorus Bray and Kurtz (1945) method was used to determine the available phosphorus in the soil. Five grams (5 g) of soil that had been sieved through 2 mm sieve were weighed into an extraction bottle. Fifty milliliters (50 mL) of Bray 1 solution was added. The suspension was shaken for 3min in a reciprocating shaker, after which the suspension was allowed to settle and then filtered through Whatman No 42 filter paper into a 100 mL volumetric flask and made up to volume. The phosphorus content in the filtrate was determined by using the molybdate-ascorbic acid colour development method of Watanabe and Olsen (1965) described below. An aliquot of 5 mL was pipetted from the supernatant into 50 mL volumetric flask in triplicate and pH adjusted with para-nitrophenol indicator. Few drops of ammonium hydroxide (4 M NH4OH) were added till the colour changed to yellow, distilled water was added till the colourless solution was observed. Reagent A was prepared by dissolving 12 g of ammonium molybdate and 0.2998 g of antimony potassium tatrate in 250 mL distilled water. Reagent B was prepared by weighing and dissolving 1.056 g of ascorbic acid in 200 mL of Reagent A. The dissolved reagents were added to 1000 mL of 2.5M H2SO4 mixed thoroughly and made to volume in 2000 mL volumetric flask. Eight milliliters (8 mL) of Reagent B was added to the solution in the flask and made to 50 mL mark with distilled water. A blank was prepared by 28 University of Ghana http://ugspace.ug.edu.gh using 5 mL of distilled water and 8 mL of Reagent B. Philips PU8620 spectrophotometer was -1 calibrated using 25 mgL standard P solutions. The colour intensity was determined on the Spectrophotometer at wavelength of 712 nm. The available phosphorus concentration in the soil sample was calculated using the spectrophotometer reading as follows. ( ) P (%) = × 100 3.2.9 Exchangeable bases and cation exchange capacity. 3.3.0 Exchangeable bases determination Ten grams (10 g) of soil that had been sieved through 2 mm sieve were weighed into 200 mL extraction bottle, 100 mL of 1N ammonium acetate (NH4OAC) solution buffered at pH 7.0 was added to the soil in the extraction bottle. The bottle was then placed on a mechanical shaker, shaken for 1hr and centrifuged at 3000 rpm for 20 min. The solution was filtered through Whatman No 42 filter paper into a clean bottle. An aliquot was taken from the filtrate in the bottle and used for determination of Ca, Mg, K and Na. The Atomic Absorption Spectrometer was used for reading the content of Ca, Mg, K and Na in solution calculated as follows: Ca (cmol/kg) = Where 40 = Atomic mass of Ca -1 R= AAS reading in mgL E = Charge of Ca 29 University of Ghana http://ugspace.ug.edu.gh Mg (cmol/kg) = Where 24 = Atomic mass of Mg -1 R= AAS reading in mgL E = Charge of Mg K (cmol/kg) = Where 39 = Atomic mass of K -1 R= AAS reading in mgL E = Charge of K Na (cmol/kg) = Where 22 = Atomic mass of K -1 R= AAS reading in mgL E = Charge of Na 3.3.1 Cation Exchange Capacity Ten grams (10 g) of soil that had been sieved through 2 mm sieve was weighed into 200 mL extraction bottle, 100 mL of 1N ammonium acetate (NH4OAC) solution buffered at pH 7.0 was added to the soil in the extraction bottle. The bottle was placed in a mechanical shaker and 30 University of Ghana http://ugspace.ug.edu.gh shaken for 1 hr, and centrifuged at 3000 rpm for 20 min. The solution was filtered through Whatman No 42 filter paper into a clean bottle. The residual soil obtained after filtration was immediately leached with 25 mL methanol into empty bottles. The soil was again leached with 25 mL portion of acidified 1M KCl into another empty bottle. Ten milliliters (10 mL) of the leachate from leaching with portions of acidified KCl was pipetted into a Kjedahl flask and 10 mL of 40% NaOH was added and then distilled. The distillate was trapped in 2% boric acid and -1 titrated against 0.01M HCl. The cation exchange capacity in cmol kg soil was then calculated from the number moles of HCl consumed in the back titration. 3.4 Biochar types used The feedstocks used for the biochar production are rice husk, sawdust and corn cob. These biochar types were produced by pyrolysis technique described by Lehmann et al (2003) at a temperature of 500°C in kiln at Soil Research Institute (SRI) in Kumasi. After the pyrolysis the biochar samples obtained were ground and the particles homogenized by sieving through 2 mm sieve and analysed for pH, total P and total surface area. 3.4.1 Determination of total surface area of biochar The total surface area of the biochar material was determined using Sears‟s method for silica- based material, 1.5 g of biochar sample was added to 100 mL dilute hydrochloric acid (pH 3) in 250 mL flask whilst agitating the mixture. Thirty grams (30 g) of sodium chloride was added with stirring to the mixture and the volume made to 150 mL mark using deionised water. The 31 University of Ghana http://ugspace.ug.edu.gh solution was titrated against 0.1M NaOH and the volume required to raise the pH from 4 to 9 recorded. The total surface area was calculated using the relation 2 (m / g) = 32V – 25 Where V = the volume of sodium hydroxide required for raising the pH from 4 to 9. 3.5 Cow dung used Cured cow dung sample was obtained from Livestock and Poultry Research Centre (LIPREC) of University of Ghana for the experiment. The cured cow dung sample was air dried under room temperature, sieved through 0.5 mm sieve and used for the experiment. The concentrations of nitrogen, phosphorus and potassium in the cow dung were determined as described earlier. 3.6 Laboratory experiment 3.6.1 Leaching of water soluble basic cations and phosphorus Three biochar types sawdust, rice husk and corn cob were packed in columns to determine the concentrations of water soluble cations and phosphorus present in these biochar types. The 3 columns were made of acrylic cylinders with volume of 1000 cm . The bottoms of the columns were covered with Whatman No 42 filter paper, followed by nylon mesh of size 25 µm pore size. The filter paper and nylon mesh were secured at the mouth with circular metal clips to prevent biochar particles from falling. 32 University of Ghana http://ugspace.ug.edu.gh The biochar samples were sieved through 0.5 µm sieve to obtain uniform particle size among the biochar samples. One hundred and fifty (150) g of each biochar sample was weighed into the 3 acrylic cylinder and packed to 200 cm by gently tapping the sides of the cylinders. The set up was replicated three times for each biochar type. The set up is shown in Fig. 1. The columns were completely leached with deionised water and the leachate collected in 1000 mL conical + 2+ 2+ + flask placed under the columns and the concentrations of K , Ca , Mg , Na and P were determined. Figure 1. Set-up for leaching of soluble cations and phosphorus 33 University of Ghana http://ugspace.ug.edu.gh 3.6.2 Retention of nitrogen Two point one (2.1) g of (NH4)2SO4 was dissolved in 500 mL of deionised water and allowed to pass through the leached biochar sample in the column described above. A constant head of 50 cm was maintained and the leachate collected. The concentration of NH4-N in every 50 mL of leachate collected and the amount of NH4-N retained by the biochar types was determined and calculated as follows: A = M1 - M2 / W Where A = amount of NH4-N retained by the biochar M1 = Mass of NH4-N applied M2 = Mass of NH4-N in leachate W = weight of biochar in the column For nitrate retention, 3.42 g of KNO3 was dissolved in 500 mL of deionised water and allowed to pass through the leached biochar sample in the column described above. A contant head of 50 cm was maintained and the leachate collected. The concentration of NO3-N in every 50 mL of leachate collected determined and the amount of NO3-N retained by the biochar types was calculated as follows: A = M1 - M2 / W Where 34 University of Ghana http://ugspace.ug.edu.gh A = amount of NO3-N retained by the biochar M1 = Mass of NO3-N applied M2 = Mass of NO3-N in leachates W = weight of biochar in the column For the retention of both NH4-N and NO3-N, 1.28 g of NH4NO3 was dissolved in 500 mL of deionized water and allowed to pass through the leached biochar sample in the column described above. A contant head of 50 cm was maintained and the leachate collected. The concentration of NH4-N and NO3-N in every 50 mL of leachate collected determined and the amount of NH4-N or NO3-N retained by the biochar types was calculated as follows: A = M1 - M2 / W Where A = amount of NH4-N/ NO3-N retained by the biochar M1 = Mass on NH4-N/NO3-N applied M2 = Mass of NH4-N/NO3-N in leachates W = weight of biochar in the column 3.7 Plant culture experiments 2.3 kg soil of the Keta and Nyankpala series were weighed into experimental pots of height 15 cm and 8 cm in diameter. Four holes were created at the bottom of the pots and the holes plugged 35 University of Ghana http://ugspace.ug.edu.gh with cotton wool to prevent soil particles from falling. The moisture content of the soil was maintained at 80% field capacity. Each pot was placed in a bowl to allow collection of leachate and the treatments below (table 1) were imposed. In all forty treatments were replicated three times and completely randomised. Four seeds of Obaatanpa maize variety were sown per pot and thinned to 2 plants per pot after germination. Table 1: Treatments CD (30t/ha) RH20 (F) (132.5 kg N/ha) + CD (15 t/ha) ASS (265 kg N/ha) CD (30t/ha) + SD40 ASP (265 kg N/ha) SD40 (F) (265 kg N/ha) CD (15t/ha) + ASS (132.5 N/ha) SD40 + ASP (265 kg N/ha) CD (30t/ha) + SD20 SD40 (F) (132.5 kg N/ha) + CD (15 t/ha) SD20 (F) (265 kg N/ha) CD (30t/ha) + RH40 SD20 + ASP (265 kg N/ha) RH40 (F) (265 kg N/ha) SD20 (F) (132.5 kg N/ha) + CD (15 t/ha) RH40 + ASP (265 kg N/ha) CD (30t/ha) + RH20 RH40 (F) (132.5 kg N/ha) + CD (15 t/ha) RH20 (F) (265 kg N/ha) RH20 + ASP (265 kg N/ha) ASP: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: -1 Cowdung, CDASS: Cowdung + Ammonium sulphate solution, RH20: 20 t ha Rice husk -1 -1 -1 biochar, SD20: 20 t ha sawdust biochar, RH40: 40 t ha rice husk biochar, SD40: 40 t ha -1 sawdust biochar, RH20 (F): 20 t ha rice husk biochar fortify with ammonium sulphate -1 fertilizer, RH40 (F): 40 t ha rice husk biochar fortify with ammonium sulphate fertilizer, -1 SD20 (F): 20 t ha sawdust biochar fortify with ammonium sulphate fertilizer, SD40 (F): -1 40 t ha sawdust biochar fortify with ammonium sulphate fertilizer. 36 University of Ghana http://ugspace.ug.edu.gh At 14 and 28 days after planting (DAP) the moisture content of the soils was brought above 100% field capacity in order to leach soils. The leachate collected was analysed for available nitrogen content. Maize plants were grown and harvested 5 weeks after planting. The harvested plants were separated into shoots and roots, and dried in an oven at a temperature of 68°C for 48 hrs to determine dry matter weight and Nitrogen content in the shoots. In order to investigate the residual effects of the treated soils, maize plants were grown for another five weeks. The soils were also leached on 14 and 28 DAP for analysis of available nitrogen content. The dry weights of the roots and shoots were determined, and nitrogen contents in the shoots were analysed. 3.8 Data Analysis th The data collected were analysed using Genstats (9 edition) and the means separated at Least Significance level of 5%. 37 University of Ghana http://ugspace.ug.edu.gh CHAPTER FOUR RESULTS AND DISCUSSION 4.1 Soil characteristics Some of the physical and chemical characteristics of the soils used are shown in Table 2. Particle size analysis showed that the Keta series had 90% sand, 7% silt and 3% clay, whilst the Nyankpala series had 68% sand, 24% silt and 8% clay. Based on the textural table, the Keta series is classified as sandy and Nyankpala series as sandy loam. These classifications agree with those of Awadzi et al. (2008) and Ziblim et al. (2012) who classified Keta and Nyankpala soils as sandy and sandy loam, respectively. The bulk densities for the Keta and Nyankpala soils were 3 1.63 and 1.58 g/ m , respectively. These values are within the range ideal for plants growth as documented by Arshad et al. (1996). According to Ziblim et al. (2012) the critical value is 2.1 g -3 m and since the bulk densities for the soils used are below the critical value, bulk density will not be a limiting factor. The Keta series had pH of 6.6 in water which makes it slightly acidic in nature and this agrees with the findings of Asomaning et al. (2012) who reported similar pH value. The Nyanpkala series had pH in water 5.3 and is also classified as slightly acidic and this agrees with the values reported by Ziblim et al. (2012) for Nyankpala series. The organic carbon (OC) contents of the -1 -1 Keta and Nyankpala series were 3.6 g kg (0.36%) and 9.2 g kg (0.92%), respectively. These values are very low and would not maintain sustainable crop yield because Wullschleger and Garten (2004) documented that the critical value is 1%. The low values for the two soils could be attributed to sparse grass vegetation covering the soils as reported by Obeng (2000). 38 University of Ghana http://ugspace.ug.edu.gh Table 2: Physical and chemical properties of the soils used Soil properties Nyankpala Keta Sand (%) 68 90 Silt (%) 24 7 Clay (%) 8 3 Texture SL S -3 Bulk Density (Mg/m ) 1.58 1.63 pH H O ( Soil: Water, 1:1) 2 5.3 6.6 pH CaCl ( Soil: CaCl , 2:1) 2 2 5.1 6.3 -1 Organic Carbon (g kg ) 9.2 3.6 -1 Total N (g kg ) 0.7 0.2 -1 Available N (g kg ) 0.16 0.1 -1 Available P (mg kg ) 2.23 1.71 -1 Cation Exchange capacity (cmolckg ) 8.14 3.03 -1 Exchangeable bases (cmolckg ) Ca 1.1 1.02 Mg 0.54 0.50 K 0.40 0.30 Na 0.23 0.50 SL: Sandy Loam S: Sand N: Nitrogen P: Phosphorus CEC: Ca tion Exchange Capacity. 39 University of Ghana http://ugspace.ug.edu.gh Both soils had very low available and total N content. The low values could be attributed to the low OC content of the soils. The low values could also be attributed to the sandy nature of the soils since there is high leaching of N in such soils. Ziblim et .al. (2012) also reported low values for Nyankpala soil and attributed it to low OC content of the soil which could result from low litter accumulation and high decomposition rate of OM in the soils within the savanna zone. The Keta series had available P content of (1.71 mg/kg) which was relatively lower than that of -1 the Nyankpala series 2.23 mg kg (Table 2). Generally the available P contents observed in the two soils were low. The low available P content found in the Keta series might be attributed to high leaching of P in the soil as reported by Asomaning et al. (2012). The low available P observed in the Nyankpala series might be due to high P fixation in such a soil making P unavailable for plant uptake (Nartey, 1994). -1 The cation exchange capacity (CEC) of the Nyankpala series was (8.14 cmolc kg ) which was -1 comparatively higher than that of the Keta series (3.03 cmolc kg ). These values are low and very low for Nyankpala and Keta series, respectively. Both soils have low clay and OC contents and that might have accounted for the low CEC observed in them. The CEC of the soil is a colloidal property which is influenced by the clay and OM content of the soil (Landon, 1991). -1 The Keta series had Ca and Mg contents of 1.02 and 0.50 cmol kg respectively. The Ca content observed for the Keta series was normal for soils which contains shell fragments and formed on calcareous pan (Obeng, 2000). The relatively low magnesium content of the Keta series was normal for soils with such loose structure, because the higher the magnesium content of the soil -1 the more compact the structure of the soil. The Keta series had K content of 0.3 cmol kg and Na 40 University of Ghana http://ugspace.ug.edu.gh -1 0.5 cmol kg contents which were relatively higher than the amounts observed in the Nyankpala series and could be due to the close proximity of the soil sampled site to the sea. -1 -1 The Nyankpala series had Ca, Mg, K and Na contents of 1.1 cmol kg , 0.54 cmol kg , 0.4 cmol -1 -1 kg , 0.23 cmol kg respectively which was in line with the amounts reported by Ziblim et al. (2012) for soils found in the agro ecological zones within which the Nyankpala soil was sampled. 4.2 Some physical and chemical properties of the biochar types All the biochar types used for the study had alkaline pH (Table 3) resulting from the pyrolysis process which is in conformity with the findings of Struebel (2011). Among the biochar types, sawdust biochar had the highest pH (8.06) followed by corn cob biochar (7.47) and then rice husk biochar (7.35) (Table 3). The relatively higher pH observed in the sawdust biochar was in line with the findings of Zolue (2012) who had higher pH for sawdust biochar compared to that of rice husk. The relatively high pH of the sawdust biochar among the biochar types may be attributed to high basic cation content of the sawdust biochar (Table 3). -1 The rice husk biochar has the highest total P content (1246.15 mg kg ) followed by corn cob -1 -1 (938 mg kg ) and then sawdust (896 mg kg ). The rice husk biochar was obtained from charring rice husk which is a by-product of an agricultural crop therefore the high P content observed in the rice husk biochar might be due to high P fertilization of the crop in the field (Table 3). The -3 sawdust biochar had the highest total surface area (3.62 g m ) followed by the rice husk (3.02 -1 -3 mg kg ) biochar and then corn cob biochar (2.69 g m ). The high value for sawdust biochar 41 University of Ghana http://ugspace.ug.edu.gh might probably be due to high micropore spaces within the biochar because Rouquerol et al. (1999) reported that surface area of biochar is influenced by the micropore within the material. Table 3: Some physico-chemical properties of the biochar used Biochar type SD RH CC pH 8.06 7.35 7.47 Total P (mg/kg) 896.24 1246.15 938.01 3 Total surface area (g/m ) 3.62 3.02 2.69 Exchangeable bases (%) Ca 1.23 0.58 0 .71 Mg 0.68 0.30 0.39 K 1.19 0.80 0.86 Na 1.89 1.43 1.27 SD: Sawdust RH: Rice husk CC: Corn cob 4.3 Laboratory column leaching experiment 4.3.1 Leaching of water soluble ions in the biochar samples The sawdust biochar contained the highest amounts of water soluble Ca (48.28 mg) and soluble Mg (12.93 mg) followed by the corn cob biochar with Ca and Mg contents of 22.38 mg and 8.86 mg respectively (Table 4). The rice husk biochar had the lowest water soluble Ca and Mg contents of 19.13 mg and 6.93 mg. The comparatively high contents of water soluble Ca and Mg observed in the sawdust biochar might be attributed to the presence of these cations in the cell 42 University of Ghana http://ugspace.ug.edu.gh wall of woody plants. According to Marschner (1995) Ca forms an integral component of plant cell wall especially woody plants and it occurs as calcium pectate compounds in cell wall, which gives stability to the cell wall and help bind the cell together. The rice husk biochar contained the highest water soluble P followed by the corn cob biochar with a value of 157.80 mg. The sawdust biochar had the lowest P contents of 59.20 mg. The rice husk biochar was prepared from rice husk biomass which is a residue from agricultural crop. Therefore the high water soluble P content observed in the rice husk biochar might be due to high P content of the crop from which the residue was obtained. According to Angst and Sohi, 2013) nutrient elements in biochar originate from the feedstock; P and K are converted into inorganic forms and retained in biochar in particulate form during the pyrolsis process. The K contents in the three biochar types were relatively close with the range value of 31.26 mg – 48.33 mg. Table 4: Some water soluble ions in the biochar Biochar Mg (mg/kg) Ca (mg/kg) K (mg/kg) P (mg/kg) SD 12.93 48.26 31.26 59.20 RH 6.93 19.13 39.27 385.26 CC 8.86 22.38 40.33 157.80 CC: Corn cob biochar, RH: Rice husk biochar, SD: Sawdust biochar 4.3.2 Nitrogen retention When the columns were loaded with (NH4)2SO4 fertilizer solution, the sawdust biochar retained -1 the highest amount of NH4–N (2273.40 mg kg ) followed by the rice husk biochar (1809.57 mg -1 -1 kg ) then the corn cob biochar (1756.70 mg kg ) as shown in Table 5. When the biochar types 43 University of Ghana http://ugspace.ug.edu.gh -1 were loaded with KNO3 fertilizer, the highest amount of NO3-N (2283.93 mg kg ) was also -1 retained by the sawdust biochar followed by the corn cob biochar (1881.31 mg kg ) and then the -1 rice husk biochar (1743.33 mg kg ). + The sawdust biochar retained the highest amount of NH4 -N and NO3-N from the NH4NO3 fertilizer followed by the rice husk biochar whilst the corn cob biochar retained the lowest + amount of NH4-N and NO3-N from the NH4NO3. The relatively high amount of NH4 -N and NO3-N retained by the sawdust biochar when the biochar samples were loaded with the fertilizer solutions could be due to relatively high surface area of the sawdust biochar (Table 5) which provided more surfaces for N adsorption. Table 5: Amount of NH4 –N and NO3 –N retained by biochar Amount of nitrogen retained (mg/kg biochar) Fertilizer Biochar type NH4 N O3 SD (NH4)2SO4 2273.4 NA SD KNO3 NA 2283.93 SD NH4NO3 2475.1 2241.44 RH ( NH4)2SO4 1 809.57 N A RH KNO3 NA 1743.33 RH NH4NO3 1703.88 1860.32 CC ( NH4)2SO4 1 756.70 NA CC KNO3 NA 1881.31 CC NH4NO3 1022.38 1569.08 N A: not applicabl e 44 University of Ghana http://ugspace.ug.edu.gh 4.4 Amount of ammonium in leachate (First Planting) th The results for amounts of NH4-N in leachates collected from the various amended soils on 14 th and 28 days after planting (DAP) showed similar trend (Table 6). The results showed that the control treatments in Keta series retain less amounts of NH4-N as compared to the control treatments in Nyankpala series. The differences in the amounts of NH4-N retained by the two soils could be attributed to differences in clay contents, besides Keta soil was sandy whilst Nyankpala was sandy loam. High infiltration rate of sandy soil makes leaching of N and other nutrients a limiting factor to productivity in sandy soil (White et al., 1997). Addition of biochar to the soils significantly (p < 0.05) increased the retention of NH4-N in the soils. When biochar is added to the soil it increases water and nutrients retention in the amended soil. According Lehman et al. (2004) biochar addition to soil influences nutrients leaching through several mechanisms; increasing water retention in the rooting zone through direct binding, sorbing nutrients or by interacting with other soil constituents. Biochar contains negative charge site therefore when added to soil it holds cations and prevents leaching of cations in the soil. According to Laing et al. (2006), the high surface charge of biochar enables biochar to hold + cations such as NH4 by cation exchange. These could have accounted for the enhancement in N retention noticed in the biochar amended treatment as compared to treatments with no biochar. 45 University of Ghana http://ugspace.ug.edu.gh Table 6: Amount of NH4-N leached (first planting) Feedstocks/Rates + Soils Treatments (NH4 -N mg/kg) ASP ASS CD CDASS Dα Dγ Dα Dγ Dα Dγ Dα Dγ Keta Control 21.58a 16.20a 20.80a 16.31a 20.93a 15.31a 21.60a 15.22a RH20 5.79c 4.03c 5.37c 3.87c 5.47c 3.48c 4.91c 4.04c RH40 5.41c 3.91c 5.34c 3.60c 4.99c 3.40c 5.47c 3.90c SD20 5.01c 3.68c 5.67c 3.97c 6.05c 3.51c 6.10c 3.69c SD40 6.17c 3.38c 5.08c 3.36c 5.38c 3.17c 5.90c 3.41c Nyankpala Control 10.44b 7.72b 10.55b 8.08b 10.13b 7.82b 9.34b 7.91b RH20 1.74d 1.93d 2.08d 1.82d 1.76d 1.74d 1.85d 1.32d RH40 1.98d 1.68d 2.01d 1.55d 1.90d 1.83d 1.64d 1.91d SD20 2.66d 1.33d 2.20d 2.06d 1.90d 1.53d 1.83d 2.37d SD40 2.24d 1.45d 1.74d 1.98d 1.98d 1.56d 1.89d 2.04d th th Dα; leahate c ollected on 14 da y after plan ting, Dγ : l eahate co llected on 28 day after p lan ting, AS P: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow dung, CDASS: Cow dung + Ammonium sulphate solution, RH -1 -1 -1 -1 20: 20 t ha Rice husk biochar, SD20: 20 t ha sawdust biochar, RH40: 40 t ha rice husk biochar, SD 40: 40 t ha sawdust biochar. Values for leachate collected on the same day with same alphabet are not significantly different at p= 0.05 46 University of Ghana http://ugspace.ug.edu.gh 4.5 Amount of ammonium in leachate (Second Planting) Table 7 shows the results for the quantity of NH4-N in leachates from the various amended soils. The results showed that, among the controls the quantity of NH4-N from the Keta series was significantly higher (p < 0.05) than that of the Nyankpala series. Therefore the control treatments in Keta series, retained less amount of NH4-N as compared to that of the Nyankpala series. This could be attributed to the sandy nature of the Keta series which makes it more susceptible to leaching. Sandy soils and ferrallitic soils due to low clay content, poor nutrients and water retention makes them susceptible to leaching (Zotarelli et al., 2007, Sitthaphnit et al., 2009). Impact of biochar on N retention in Keta series was significantly (p < 0.05) higher than in the Nyankapala series. The Keta series is sandy and has larger pore spaces with poor water holding capacity therefore addition of the biochar might have greatly enhanced its water holding capacity and nutrients retention. Addition of biochar significantly (p < 0.05) increased the retention of NH4-N in the two soils. Amending soil with biochar enhances soil aggregation which helps to improve water and nutrients retention (Yoo et al., 2014; Xu et al., 2016). It is therefore observed that the trend of leaching was similar in the first and second planting periods, except the quantities of NH4-N leached were different. 47 University of Ghana http://ugspace.ug.edu.gh Table 7: Amount of NH4-N leached (second planting) + Soils Feedstocks/Rates Treatments ( NH4 -N m g/kg) ASP ASS CD CDASS Dα Dγ Dα Dγ Dα Dγ Dα Dγ Keta Control 8.68a 3.99a 9.24a 4.03a 9.50a 3.97a 9.50a 4.21a RH20 1.75c 0.56c 2.00c 0.40c 2.22c 0.55c 1.94c 0.52c RH40 2.25c 0.46c 1.93c 0.41c 1.96c 0.43c 2.40c 0.50c SD20 2.00c 0.52c 2.06c 0.55c 2.21c 0.51c 2.47c 0.50c SD40 2.53c 0.47c 2.14c 0.45c 1.98c 0.46c 2.16c 0.42c N yankpala Control 6 .70b 1.98b 6 .81b 1.69b 6.05b 1.43b 6.22b 1 .52b RH20 1.61c 0.53c 1.92c 0.52c 1.74c 0.49c 2.01c 0.48c RH40 2.31c 0.48c 1.60c 0.45c 1.75c 0.49c 1.58c 0.52c SD20 2.07c 0.54c 1.91c 0.53c 1.93c 0.62c 2.14c 0.38c SD40 1.85c 0.56c 1.64c 0.46c 1.59c 0.50c 1.77c 0.47c th th Dα: leahate collected on 14 day after planting, Dγ: leahate collected on 28 day after planting, ASP: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow dung, CDASS: Cow dung + Ammonium sulphate solution, RH -1 -1 -1 -1 20: 20 t ha rice husk biochar, SD20: 20 t ha sawdust biochar, RH40: 40 t ha rice husk biochar, SD40: 40 t ha sawdust biochar. Values for leachate collected on the same day with same alphabet are not significantly different at p = 0.05 48 University of Ghana http://ugspace.ug.edu.gh 4.6 Amount of nitrate in leachate th th The results in Table 8 shows the amounts of NO3-N in leachates collected on the 14 and 28 DAP during the first planting. The results indicated that among the controls, the Nyankpala series retained significantly (p < 0.05) higher amount of NO3-N as compared to the Keta series. The Keta series is sand whilst the Nyankpala series is sandy loam so this could have made the Keta series more susceptible to leaching than the Nyankpala series. Leaching of nitrogen is one - of the most common ways through which nitrogen especially NO3 is lost from the soil system, with the situation being severe in sandy soil and under heavy rainfall (Razzaque and Hannafi, 2005). Amending the two soils with biochar significantly (p < 0.05) enhanced the amount of NO3-N retained in the two soils and reduced the amount of NO3-N leached. Biochar material has positive charge sites therefore when applied to the soil can hold anions like nitrate which helps to prevent leaching of nitrate in the soil. There are also positive charge sites on biochar which gives anion exchange capacity to the material which can attract nitrate and phosphate ions (Chintala et th th al., 2015). Table 9 shows the amounts of NO3-N in leachates collected on the 14 and 28 days after second planting. Although the amounts of NO3-N contained in the leachates were lower than that collected during the first planting, the trends were similar in both cases. 49 University of Ghana http://ugspace.ug.edu.gh Table 8: Amount of NO3-N leached (first planting) Feedstocks/Rates - Soils Treatments (NO3 -N mg/kg) ASP ASS CD CDASS Dα Dγ Dα Dγ Dα Dγ Dα Dγ Keta Control 8.56a 6.99a 8.21a 7.44a 9.13a 7.01a 9.15a 7.49a RH20 2.01c 0.79c 2.35c 0.77c 2.34c 0.71c 2.08c 0.66c RH40 2.35c 0.70c 2.70c 0.65c 1.69c 0.72c 2.64c 0.79c SD20 2.03c 0.79c 2.69c 0.73c 2.70c 0.69c 2.63c 0.80c SD40 2.68c 0.82c 2.26c 0.73c 2.66c 0.73c 1.99c 0.77c Nyankpala Control 6.07b 3.13b 5.10b 3.26b 6.12b 3.33b 5.42b 2.98b RH20 1.88c 0.30c 2.20c 0.29c 2.23c 0.32c 1.57c 0.31c RH40 1.89c 0.32c 2.21c 0.40c 1.56c 0.35c 2.23c 0.32c SD20 2.22c 0.31c 1.55c 0.29c 1.89c 0.33c 1.58c 0.33c SD40 1.54c 0.31c 1.91c 0.28c 1.88c 0.30c 2.22c 0.32c th th D α; leahate c ollected on 14 da y after plan ting, Dγ : l eahate co llected on 28 day after p lan ting, AS P: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow dung, CDASS: Cow dung + Ammonium sulphate solution, RH -1 -1 -1 -1 20: 20 t ha Rice husk biochar, SD20: 20 t ha sawdust biochar, RH40: 40 t ha rice husk biochar, SD 40: 40 t ha sawdust biochar. Values for leachate collected on the same day with same alphabet are not significantly different at p = 0.05 50 University of Ghana http://ugspace.ug.edu.gh Table 9: Amount of NO3-N leached (Second planting) Feedstocks/Rates - Soils Treatments (NO3 -N mg/kg) ASP ASS CD CDASS Dα Dγ Dα Dγ Dα Dγ Dα Dγ Keta Control 3.83a 4.19a 3.94a 4.33a 3.91a 3.95a 3.68a 4.38a RH20 0.57c 0.55c 0.47c 0.57c 0.42c 0.54c 0.44c 0.47c RH40 0.49c 0.59c 0.47c 0.64c 0.41c 0.58c 0.43c 0.56c SD20 0.60c 0.67c 0.45c 0.55c 0.55c 0.51c 0.47c 0.53c SD40 0.47c 0.66c 0.46c 0.55c 0.50c 0.60c 0.48c 0.57c Nyankpala Control 2.13b 2.02b 2.00b 2.09b 2.03b 2.12b 2.05b 1.95b RH20 0.54c 0.57c 0.52c 0.60c 0.47c 0.53c 0.43c 0.39c RH40 0.48c 0.49c 0.52c 0.52c 0.50c 0.57c 0.43c 0.38c SD20 0.65c 0.50c 0.49c 0.57c 0.47c 0.55c 0.54c 0.43c SD40 0.43c 0.48c 0.39c 0.57c 0.43c 0.52c 0.40c 0.56c th th D α; leahate c ollected on 14 da y after plan ting, Dγ : l eahate co llected on 28 day after p lan ting, AS P: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow dung, CDASS: Cow dung + Ammonium sulphate solution, RH -1 -1 -1 -1 20: 20 t ha Rice husk biochar, SD20: 20 t ha sawdust biochar, RH40: 40 t ha rice husk biochar, SD 40: 40 t ha sawdust biochar. Values for leachate collected on the same day with same alphabet are not significantly different at p = 0.05 51 University of Ghana http://ugspace.ug.edu.gh 4.7 Shoot and root dry weights of maize The results for dry matter (DM) of maize grown in the various amended soils during the first planting are shown in Figs. 2 and 3, respectively. The shoot and root dry weights produced by the control treatments in both soils were not significantly (p > 0.05) different from each other. This could be attributed to the inherent low plant nutrients, especially N of the two soils used (Table 2). Amending the two soils with biochar significantly (p < 0.05) increased the DM yield. This increment in DM yield could be due to the N fertilizer adsorbed by the biochar and made available for uptake. According to Taghizadel et al. (2012) recent evidence has indicated that N adsorbed by biochar is eventually made available for plant uptake. Ma and Matsunaka (2013) reported that when biochar is applied as sole amendment or together with N fertilizer, it significantly improved DM of shoots and roots of lettuce. Similar trend was also observed during the second planting as shown in Fig. 4 and 5. 14 12 10 8 ASP 6 ASS 4 2 CD 0 CDASS K NY K NY K NY K NY K NY 0 RH20 RH40 SD20 SD40 Soil/biochar st Figure 2: Shoot dry weight of maize (1 planting) 52 Dry shoot weight (g/pot) University of Ghana http://ugspace.ug.edu.gh 14 12 10 8 ASP 6 ASS 4 CD 2 CDASS 0 K NY K NY K NY K NY K NY 0 RH20 RH40 SD20 SD40 Soil/biochar st Figure 3: Root dry weight of maize (1 planting). K: Keta series, NY: Nyankpala series, ASP: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow dung, CDASS: Cow dung + Ammonium sulphate -1 -1 -1 solution, RH 20: 20 t ha Rice husk biochar, SD 20 t ha sawdust biochar, RH40: 40 t ha -1 rice husk biochar, SD40: 40 t ha sawdust biochar. 14 12 10 8 ASP 6 4 ASS 2 CD 0 CDASS K NY K NY K NY K NY K NY 0 RH20 RH40 SD20 SD40 Soil/biochar nd Figure 4: Shoot dry weight of maize (2 planting) 53 Dry shoot weight(g/pot) Dry root weight(g/pot) University of Ghana http://ugspace.ug.edu.gh 14 12 10 8 ASP 6 ASS 4 CD 2 CDASS 0 K NY K NY K NY K NY K NY 0 RH20 RH40 SD20 SD40 Soil/biochar nd Figure 5: Roots dry weight of maize (2 planting). K: Keta series, NY: Nyankpala series, ASP: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow dung, CDASS: Cow dung + Ammonium sulphate -1 -1 -1 solution, RH 20: 20 t ha Rice husk biochar, SD 20 t ha sawdust biochar, RH40: 40 t ha -1 rice husk biochar, SD 40: 40 t ha sawdust biochar 54 Dry root weight(g/pot) University of Ghana http://ugspace.ug.edu.gh Table 10: N Concentration in maize after harvest Feedstocks/Rates Soils Treatments (% N in maize) ASP ASS CD CDASS Dɸ Dʂ Dɸ Dʂ Dɸ Dʂ Dɸ Dʂ Keta Control 0.13 0.12 0.11 0.10 0.14 0.12 0.14 0.09 RH20 0.39 0.41 0.49 0.39 0.38 0.35 0.45 0.33 RH40 0.35 0.30 0.40 0.37 0.33 0.29 0.38 0.37 SD20 0.46 0.39 0.42 0.31 0.49 0.32 0.48 0.39 SD40 0.39 0.32 0.46 0.30 0.48 0.39 0.35 0.30 Nyankpala Control 0.19 0.16 0.18 0.15 0.17 0.15 0.12 0.17 RH20 0.54 0.44 0.50 0.39 0.50 0.35 0.49 0.37 RH40 0.56 0.39 0.48 0.37 0.49 0.38 0.53 0.48 SD20 0.53 0.46 0.54 0.45 0.53 0.39 0.56 0.38 SD40 0.57 0.42 0.53 0.40 0.57 0.42 0.58 0.43 D ɸ; %N in maize plants after f irst planti ng, Dʂ: % N in ma ize plan ts after se cond p lan ting, AS P: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow dung, CDASS: Cow dung + Ammonium sulphate solution, RH -1 -1 -1 -1 20: 20 t ha Rice husk biochar, SD20: 20 t ha sawdust biochar, RH40: 40 t ha rice husk biochar, SD 40: 40 t ha sawdust biochar. 55 University of Ghana http://ugspace.ug.edu.gh 4.8 Nitrogen uptake in maize The results for N concentration and N uptake in maize are shown in Tables 10 & 11 respectively. The N concentration in maize was used in calculating N uptake in maize. There were no significant (p > 0.05) differences between the control treatments of Keta and Nyankpala series in terms of N uptake. This might probably be due to low N contents of the two soils. Amending the soils with biochar significantly (p < 0.05) enhanced N uptake. Addition of biochar to the two soils enhanced N retention in the soils, which might helped in making the retained N available for possible uptake by the maize plant. Emperical evidence confirms that biochar improves water and nutrients retention by enhancing electrostatic adsorption sites (Lehman et al., 2003). According to Taghizadel et al. (2012) it has been suggested that N adsorbed by biochar is eventually released for plants uptake. N uptake in Nyankpala treatments amended with biochar was significantly higher (p < 0.05) than N uptake in Keta treatments with biochar. Nyankpala series has relatively higher N content as compare to the Keta series and that might have accounted for the higher N uptake observed in Nyankpala treatments with biochar. Uptake of N in the maize during the second planting follows similar trend. 56 University of Ghana http://ugspace.ug.edu.gh Table 11: Nitrogen uptake in maize Soils Feedstocks/Rates Treatments ( N mg/pot) ASP ASS CD CDASS N∞ N⸙ N∞ N⸙ N∞ N⸙ N∞ N⸙ Keta Control 8.97a 9.64e 9.54a 7.94e 8.89a 6.56f 9.02a 7.46e RH20 51.47b 43.80f 59.37b 51.38f 52.01b 40.64f 60.10b 48.05f RH40 51.60b 50.49f 47.87b 52.71f 56.37b 43.36f 54.12b 50.66f SD20 51.29b 47.37f 54.53b 54.64f 50.52b 45.02f 47.85b 50.31f SD40 52.36b 44.19f 55.77b 51.71f 53.62b 42.87f 52.70b 50.42f Nyankpala Control 9.47a 8 .04e 8.29a 6.69e 1 1.60a 6 .68e 1 3.58a 8 .38e RH20 84.13c 77.09g 78.70c 66.36g 81.77c 69.89g 73.34c 74.11g RH40 78.43c 76.21g 86.91c 67.55g 87.88c 72.57g 86.37c 68.93g SD20 81.09c 65.46g 75.99c 73.68g 84.78c 68.93g 83.29c 71.48g SD40 79.79c 74.31g 64.66c 67.26g 81.41c 66.50g 71.65c 73.09g N∞: N uptake in maize (first planting), N⸙: N uptake in maize (second planting) ASP: Ammonium sulphate fertilizer pellet, -1 ASS: Ammonium sulphate solution, CD: Cow dung, CDASS: Cow dung + Ammonium sulphate solution, RH 20: 20 t ha Rice -1 -1 -1 husk biochar, SD 20 t ha sawdust biochar, RH40: 40 t ha rice husk biochar, SD 40: 40 t ha sawdust biochar. Values under same planting period with same alphabet are not significantly different at p= 0.05 57 University of Ghana http://ugspace.ug.edu.gh 4.9 Available N content of residual soil after planting The results for NH4-N and NO3-N contents in the residual soil after planting are shown in Tables 12 and 13. Results indicated that the amounts of NH4-N and NO3- N in the control treatments of Nyankpala series were significantly (p < 0.05) higher than that of theKeta series. It is known from this study that Nyankpala series is less susceptible to leaching than the Keta series and this observation could be attributed to its high clay content. The relatively high clay and N contents of the Nyankpala series could have accounted for the high amount of available N found in the residual soil. Amending the two soils with biochar significantly (p < 0.05) enhanced the amount of NH4-N and NO3- N in the soils. Probably the biochar was able to hold the fertilizer N applied and also increase the water holding capacity of the soil which might have helped to retain the N in the soil and that could account for the high amount of available N found in the residual soils of the amended treatments. Biochar addition to the soil reduced N leaching which helps in making the N available for plant uptake (Lehmanet al., 2003). There were no significant (p ˃ 0.05) differences between the amounts of NH4-N/NO3-N retained in the biochar amended treatments in both soils. Although the amounts of available N in the residual soils after second planting were lower than that of the first planting the trend was similar. 58 University of Ghana http://ugspace.ug.edu.gh Table 12: Residual soil available N (1st planting) Soils Feedstocks/Rates + Treatments ( NO3-N/ NH4 -N mg/kg) ASP ASS CD CDASS NH4 NO 3 NH4 NO 3 NH4 NO 3 NH4 NO3 Keta Control 18.43a 18.86f 19.77a 17.99f 21.21a 18.8f 22.42a 19.64f RH20 39.62c 80.1h 43.35c 81.1h 44.06c 79.42h 41.82c 81.01h RH40 40.11c 84.87h 43.44c 76.83h 41.21c 76.57h 43.4c 78.78h SD20 39.79c 79.29h 42.85c 78.43h 41.96c 79.61h 44.27c 80.15h SD40 45.08c 77.87h 44.47c 81.72h 48.4c 65.93h 45.75c 76.96h Nyankpala Control 2 6.66b 3 3.32g 27.85b 3 4.03g 29.84b 38.75g 29.53b 42.45g RH20 54.49d 96.73j 53.98d 92.69j 55.22d 102.16j 53.63d 99.82j RH40 56.51d 95.53j 55.45d 100.29j 55.54d 97.46j 57.88c 94.2j SD20 56.27d 96.09j 52.17d 93.02j 56.13d 104.56j 52.84d 95.61j SD40 55.93d 93.94j 54.57d 95.38j 57.51d 100.44j 58.24d 105.19j ASP: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow dung, CDASS: Cow dung + -1 -1 -1 Ammonium sulphate solution, RH 20: 20 t ha Rice husk biochar, SD 20 t ha sawdust biochar, RH40: 40 t ha rice husk -1 biochar, SD 40: 40 t ha sawdust biochar. Values under same available N with same alphabet are not significantly different at p = 0.05 59 University of Ghana http://ugspace.ug.edu.gh nd Table 13: Residual soil available N (2 planting) Soils Feedstocks/Rates + Treatments ( NO3-N/ NH4 -N mg/kg) ASP ASS CD CDASS NH4 NO3 NH4 NO3 NH4 NO3 NH4 NO3 Keta Control 6.14r 12.51u 6.59r 11.12u 9.07r 10.42u 7.44r 9.03u RH20 19.71t 39.12w 14.65t 34.83w 15.53t 43.52w 16.05t 34.38w RH40 16.83t 39.46w 19.73t 38.13w 20.19t 40.59w 20.99t 43.99w SD20 12.80t 42.77w 17.88t 35.17w 19.16t 34.08w 16.37t 42.51w SD40 16.42t 33.21w 17.24t 32.35w 19.34t 37.6w 18.66t 37.93w N yankpala Control 1 1.92rs 1 8.49v 1 2.49rs 16.82v 15.86s 17.56v 10.7r 1 8.5v RH20 27.65p 58.47y 29.89p 54.48y 28.64p 56.83y 28.75p 60.49y RH40 31.29p 61.68y 31.97p 55.97y 29.29p 5.66y 34.91p 53.62y SD20 27.95p 57.95y 35.25p 60.66y 27.12p 55.84y 33.29p 63.04y SD40 35.23p 59.84y 28.87p 53.48y 38.92p 52.87y 34.87p 58.95y ASP: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow dung, CDASS: Cow dung + -1 -1 -1 Ammonium sulphate solution, RH 20: 20 t ha Rice husk biochar, SD 20 t ha sawdust biochar, RH40: 40 t ha rice husk -1 biochar, SD 40: 40 t ha sawdust biochar. Values under same available N with same alphabet are not significantly different at p = 0.05 60 University of Ghana http://ugspace.ug.edu.gh 4.9.1 Residual soils pH Residual soils pH At the end of the experiment the Keta and Nyankpala soils treated with only N fertilizer source showed significant (p < 0.05) decrease in soil pH (Tables 14 & 15). The decrease in pH could be due to leaching of the basic cations. However, the amendment of the soils with biochar did not have significant (p < 0.05) influence on the pH of the residual soils after planting. Although biochar material has basic cation which gives liming properties, but probably the planting duration was not long enough for the biochar to mineralize to release the basic cations in it. Biochar material contains nutrients therefore when incorporated in soil, it mineralizes to release basic cations such as K, Ca and Mg Glaser et al. (2002) and (Keith et al., 2011; Zimmerman et al., 2011). 61 University of Ghana http://ugspace.ug.edu.gh st Table 14: pH of residual soils after 1 planting Soils Feedstocks/Rates Treatments ASP ASS CD CDASS Keta 0 6.5 6.4 6.5 6.6 Nyankpala 4.9 4.8 5.0 5.1 Keta R H20 6.8 6.9 6.9 6.7 Nyankpala 5.3 5.4 5.5 5.6 Keta R H40 6.9 6.9 6.8 6.9 Nyankpala 5.5 5.6 5.9 5.8 Keta SD20 6.7 6.8 6.7 6.9 Nyankpala 5.4 5.6 5.8 5.9 Keta S D40 6.9 6.8 6.7 6.8 Nyankpala 5.8 5.5 5.9 5.8 ASP: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow -1 dung, CDASS: Cow dung + Ammonium sulphate solution, RH 20: 20 t ha Rice -1 -1 huskbiochar, SD 20 t ha sawdust biochar, RH40: 40 t ha rice husk biochar, SD 40: 40 t -1 ha sawdust biochar 62 University of Ghana http://ugspace.ug.edu.gh nd Table 15: pH of residual soils after 2 planting Soils Feedstocks/Rates Treatments ASP ASS CD CDASS Keta 0 6.3 6.2 6.4 6.4 Nyankpala 4.5 4.6 4.8 4.6 Keta R H20 6.7 6.8 6.7 6.8 Nyankpala 5.0 5.1 5.3 5.1 Keta R H40 6.8 6.7 6.7 6.8 Nyankpala 5.1 5.4 5.5 5.2 Keta SD20 6.6 6.7 6.7 6.8 Nyankpala 5.2 5.4 5.5 5.4 Keta S D40 6.8 6.7 6.7 6.7 Nyankpala 5.3 5.2 5.4 5.3 ASP: Ammonium sulphate fertilizer pellet, ASS: Ammonium sulphate solution, CD: Cow -1 dung, CDASS: Cow dung + Ammonium sulphate solution, RH 20: 20 t ha Rice husk -1 -1 -1 biochar, SD 20 t ha sawdust biochar, RH40: 40 t ha rice husk biochar, SD 40: 40 t ha sawdust biochar 63 University of Ghana http://ugspace.ug.edu.gh CHAPTER SIX CONCLUSION AND RECOMMENDATION The present study was carried out in the laboratory and screen house to identify biochar type - from different feed stocks (saw dust, rice husk and corn cob) with better retention for NO3 and + NH4 (using ammonium sulphate, potassium nitrate and ammonium nitrate), ability of biochar to reduce leaching and enhance N uptake. The biochar types were applied at 0, 20 and 40 t/ha and treated with different N sources (cow dung and ammonium sulphate) in two soils (Keta and Nyankpala series) and maize was grown. Results from the column leaching experiment showed that the sawdust biochar had superior - + retention capacity for NO3 and NH4 . This could be due to its relatively higher surface area when compared to the other biochar types. Biochar amendment of the soils reduced leaching of NO3-N and NH4-N which indicated their ability to retain nitrogen in the soils. The amendment also enhanced biomass production (dry matter). Nitrogen uptakes by maize in biochar amended treatments were tremendously enhanced as compared to the control treatments. However, biochar feedstock, N source and rate of biochar application did not influence leaching and retention of N in the soils as well as N uptake. From the present study it is recommended that biochar could be applied at lower rate (e.g. 20 t/ha) to reduce leaching of N, and enhance N uptake and plant biomass in sandy soil. It is also recommended that the experiment should be conducted under field condition. 64 University of Ghana http://ugspace.ug.edu.gh REFERENCE Adomaitis, T., Z. Vaisvila, J., Mazvila, Staugaitis, G. & Fullen M. A. (2008). Influence of mineral fertilizer on nitrogen leaching. Acta Agriculturae Scandinavica Section B Soil & Plant Science. 58:3, 199-207, DOI: 10.1080/09064710701593012 Adu S. V. (1995). Soils of the Nasia basin. Memoir NO.6. Soil Research Institute. Allison, L.E. (1965). “Organic carbon”. In Methods of Soil Analysis, Edited by: Black, C. A. 1367–1378. Madison, WI: American Society of Agronomy. Angst T. E. & Sohi S. P. (2013). Establishing release dynamics for plant nutrients from biochar. GCB Bioenergy, 5, 221–226. Ahmad, M., Rajapaksha, A. U., Lim, J. E., Zhang, M., Bolan, N., Mohan, D., Vithanage, M., Lee, S. S. & Ok, Y. S. (2014). Biochar as a sorbent for contaminant management in soil and water: a review. Chemosphere. 99, 19–23. http://dx.doi.org/10.1016/j.chemosphere. 2013.10.071 Amonette, J. E. & Joseph S. (2009). Characteristics of biochar: microchemical properties In: Lehmann J., Joseph S (eds). Biochar for Environmental Management Science and Technology. Earthscan Laondon. pp 33-500. Aslam, Z., Khalid, M. & Aon, M. (2014). Impact of Biochar on Physical Properties of soil. Scholarly Journal of Agricultural Science. Vol. 4(5), pp. 280 - 284 65 University of Ghana http://ugspace.ug.edu.gh Asomaning S. K. (2011). Phosphorus fraction and sorption characteristics of some cultivated soils at Angloga, Ghana. Ph.D. Thesis in partial fulfillment of requirement for Doctor of philosophy degree in soil science University of Ghana, Legon, Accra. University of Ghana, Legon, Accra Atkinson C. J., Fitzgerald J. D. & Hipps N. A. (2010). Potential mechanisms for achieving agricultural benefits from biochar application to temperate soils: a review. Plant and Soil, 337, 1–18. Attiq-ur-Rehman, M., Yaqoob, A., Waseem, A. & Nabi, A. (2011). Flow injection method for the determination of nitrite and nitrate in water samples based on luminolchemiluminescence detection. Acta Chimica Slovenica. 58: 569-575. Awadzi, T. W., Ahiabor, E. & Breuning-Madsen, H. (2008). The Soil-Land Use System in a Sand Spit Area in the Semi-arid Coastal Savannah region of Ghana - Development, Sustainability and Threats. West African Journal of Ecology, 13, 132-143 Bai, S. H., Xu, C. Y., Blumfield, T. J., Xu, Z. H., Zhao, H., Wallace, H., Reverchon, F. & Van 15 Zwieten, L. (2015). Soil and foliar nutrient and nitrogen isotope composition (ð N) at 5 years after poultry litter and green waste biochar amendment in a macadamia orchard. Environmental Science and Pollution Research. 22: 3803-3809 Baligar, V. C., Fageria, N. K., & He, Z. L. (2001). Nutrient Use Efficiency in Plants. Communication: Soil Science & Plant Analysis.32:921-950 66 University of Ghana http://ugspace.ug.edu.gh Beaudoin, N., Saad, J.K., Van Laethem, C., Machet, J.M., Maucorps, J. & Mary, B. (2005). Nitrate leaching in intensive agriculture in Northern France: effect of farming practices, soils and crop rotations. Agriculture, Ecosystem & Environment. 111, 292–310 Beesley, L., Moreno- Jimenez, E., Gomez-Eyles, J. L., Harris, E., Robinson, B., & Sizmur, T. (2001). A review of biochar potential role in the remediation, revegetation and restoration of contaminated soils, Enciron pollution. 159: 3269-3282 Blake, G. R. & Hartge, K. H. (1986). Bulk Density. In: Klute, A., Ed., Methods of Soil Analysis, Part 1, 2nd Edition, Agronomy Monograph. 9, American Society of Agronomy and Soil Science Society of America, Madison, 363-375. Borchad, N., Siemens, J., Ladd, B., Moller, A., & Amelung, W. (2014). Application of biochars to sandy and silty soil failed to increase maize yield under common agricultural practice. Soil and Tillage Research 144 (2014) 184–194 Borchard, N., Wolf, A., Laabs, V., Aeckersberg, R., Scherer, H., Moellerand, A. & Amelung, W. (2012). Physical activation of biochar and its meaning for soil fertility and nutrient leaching a greenhouse experiment. Soil Use Management. 28, 177-184. Bourke, J., Manley-Harris, M., Fushimi, C., Dowaki, K., Nunoura, T., & Antal, M. J. (2007). Do all carbonized charcoals have the same chemical structure? A model of the chemical structure of carbonized charcoal. Industrial Engineering & Chemistry Research. 46, 5954 –5967. 67 University of Ghana http://ugspace.ug.edu.gh Brady, N. C. & Weil, R. R. (2008). The Nature and Properties of Soils.14th edition, Prentice Hall, Upper Saddle River, N. Bray, R. H. & Kurtz, L. T. (1945). Determinations of Total, Organic and Available Forms of Phosphorus in Soils. Soil Science, 59, 39-45. Brown R. (2009). Biochar production technology. In „Biochar for environmental management: science and technology‟. (Eds J Lehmann, S Joseph) pp. 127–146. (Earthscan: London) Brodowski, S., W. Amelung, L., Haumaier, C., Abetz & W. Zech. (2005). Morphological and chemical properties of black carbon in physical soil fractions as revealed by scanning electron microscopy and energy-dispersive x-ray spectroscopy. Geoderma. 128: 116– 129 Burgo, P., Madojon, E., & Cabrera F. (2006). Nitrogen mineralization and nitrate leaching of sandy soil amended with different organic wastes. Waste Management and Research. 24:175-182 Burns, R. G., DeForest, J. L., Marxsen, J., Sinsabaugh, R. L., Stromberger, M. E., Wallenstein, M. D., Weintraub, M. N. & Zoppini A. (2013). Soil enzymes in a changing environment: current knowledge and future directions. Soil biology and Biochemistry. 58, 216-234. Butnan, S., Deenik, J. L., Toomsan, B., Antal, M. J. & Vityakon P. (2016). Biochar characteristics and application rates affecting corn growth and properties of soils contrasting in texture and mineralogy. Geoderma. 237–238 (2015) 105–116 68 University of Ghana http://ugspace.ug.edu.gh Canadian Food Inspection Agency 1994. Biology Document BIO1994-11: A companion document to the Directive 94-08 (Dir 94-08), Assessment Criteria for Determining Environmental Safety of Plant with Novel Traits. Cao, X., Ma, L., Gao, B., & Harris, W. (2009). Dairy-manure derived biochar effectively sorbs lead and atrazine. Environmental Science and Techology. 43, 3285-3291. Chan, K. Y., Van Zwieten, L., Meszaros, I., Downie, A., & Joseph S. (2008). Using poultry litter biochar as soil amendment. Australian journal of soil research. 46, 437 - 444. Chaudhry, A. R., (1983). Maize in Pakistan. Punjab agriculture co-oordinating board. University of Agriculture. Faisalabad Chen, B. L., Zhou, D. D., & Zhu, L. Z., (2008). Transitional adsorption and partition of nonpolar and polar aromatic contaminants by biochars of pine needles with different pyrolytic temperatures, Environmental Science and Technology. 42, 5137–5143. Cheng, C. H., Lehmann j., & Engelhard, M. H. (2008). Natural oxidation of black carbon in soils: Changes in molecular form and surface charge along a climosequence. Geochimica et. Cosmochimica Acta.72: 1598–1610. Cheng, C. H., Lehmann, J., Thies, J. E., Burton, S. D. & Engelhard, M. H. (2006) „Oxidation of black carbon by biotic and abiotic processes‟, Organic geochemistry. Vol 37, Chintala, R., Gelderman, R. H., Schumacher, T. E. & Malo, D. D. (2015). Vegetative Corn Growth and Nutrient Uptake in Biochar Amended Soil from eroded Landscape. Archives Agronomy and Soil Science. DOI: 10.1080/03650340.2015.789870. 69 University of Ghana http://ugspace.ug.edu.gh Clough, T. J., Condron, L., Kammann, C. & Müller C. (2013). A review of biochar and soil nitrogen dynamics. Agronomy. 3, 275–293. Clough, T. J. & Condron, L. M. (2010). Biochar and the nitrogen cycle: Introduction Journal of Environmental Quality. 39, 1218–1223. Cornelissen, G., Martinsen, V., Shitumbanuma, V., Alling, V., Breedveld, G., Rutherford, D., Sparrevik, M., Hale, S., Obia, A. & Mulder, J. (2013). Biochar effect on maize yield and soil characteristics in five conservation farming sites in Zambia. Agronomy 3, 256 -274 Craig, R. A., Leo, M. C., Tim, J. C., Mark, F., Alison, S., Robert, A. H., & Robert R. S. (2011). Biochar induced soil microbial community change: implications for biogeochemical cycling of carbon, nitrogen and phosphorus. Pedobiologia 54: 309–320. Cui, H. J., Wang, M. K., Fu M. L. & Ci E. (2011). Enhancing phosphorus availability in phosphorus-fertilized zones by reducing phosphate adsorbed on ferrihydrite using rice straw-derived biochar. Journal of Soils and Sediments. 11, 1135-1141. Dai L., Li H., Tan F., Zhu N., He M. & Hu G. (2016). Biochar: a potential route for recycling of phosphorus in agricultural residues. Global Change Biology. 8,852-858 doi: 10.1111/gcbb. 12365. Demirbas A. (2004). Effects of temperature and particle size on bio-char yield from pyrolysis of agricultural residues. Journal Analytical Applied Pyrolysis. 72: 243–248. Dickson K. B., Benneh G. (1995). A new geography of Ghana. 3rd ed. Essex: Longman. 70 University of Ghana http://ugspace.ug.edu.gh Ding, Y., Liu Y. X., Wu, W. X., Shi, D. Z., Yang, M. & Zhong, Z. K. (2010). Evaluation of biochar effects on nitrogen retention and leaching in multi-layered soil columns. Water, Air and Soil Pollution. 213, 47-55. Doan, T. T., Henry-des-Tureaux, T., Rumpel, C., Janeau, J. L. & Jouquet, P. (2015). Impact of compost, vermicompost and biochar on soil fertility, maize yield and soil erosion in northern Vietnam: a three year mesocosm experiment. Journal of Science of the Total Environment. 514, 147–154. DOI: 10.1080/03650340.2015.1115018 Dorioz, J. M., Robert, M. & Chenu, C. (1993). The role of roots, fungi and bacteria in clay particle organisation: An experimental approach. Geoderma 56:179-194. Dume, B., Mosissa, T. & Nebiyu A. (2016). Effect of biochar on soil properties and lead (Pb) availability in a military camp in South West Ethiopia. African Journal of Environmental Science and Technology. Vol. 10 (3), pp. 77-85. Fan, X. H. & Li C. Y. (2009). Effects of Slow‐Release Fertilizers on Tomato FAO Statistical Database. (2008) FAOSTAT: Agriculture Data . Available online: http://faostat.fao.org. Food & Agriculture Organisation. (2008). Fertilizer use by crops in Ghana. Rome Pp.39 Galinat, W. C. (1988). The origin of corn. In Sprangue, G. F. & Dudley, J. W. (eds). Corn and corn improvement. Agronomy monograph. No 18: pp 1-31. American Society of Agronomy Madison Winconsin. 71 University of Ghana http://ugspace.ug.edu.gh Gaskin, J. W., Steiner, C., Harris, K., Das, K. C. & Bibens, B. (2008). Effect of low temperature pyrolysis conditions on biochars for agricultural use. Transation of the American Society of Agricultural and Biological Engineering. 51, 2061–2069. Germano, M. G., Cannavan, F. S., Mendes, L. W., Lima, A. B., Teixeira, W. G., Pellizari, V. H. & Tsai, S. M. (2012). Functional diversity of bacterial genes associated with aromatic hydrocarbon degradation in anthropogenic dark earth of Amazonia. Pesquisa. Agropecuaria Brasileira. 47, 654–664 Gibson L., Benson G. (2002). Origin, history and uses of corn. Iowa state university department of agronomy. Githinji L. (2013). Effect of biochar application rate on soil physical properties of a sandy loam. Journal of Agriculture and Environmental Sciences. Vol 15, pp 116-367 Glaser B, Lehmann J., & Zech W. (2002). Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal - a review. Journal of Biology and Fertility of Soil. 35:219 –30. Goulding, K. (2000). Nitrate leaching from arable and horticultural land. Journal of Soil Use and Management. Volume 16, issue s1, pp 16: 145-151 Gul S., Whalen, J. K., Thomas, B. W. & Sachdeva, V. (2015). Physico-chemical properties and microbial responses in biochar – amended soils: Mechaisms and future directions. Agriculture, Ecosystems and Environmental 206 (2015) 46-59. 72 University of Ghana http://ugspace.ug.edu.gh Gwenzi, W., Chankura, N., Mukome, F. N. D., Machados, S. & Nyamasoka B. (2013). Biochar production and applications in Sub- Saharan Africa: Opportunities, constriants, risks and uncertainties. Journal of Environmental Management. volume 15, pp 250 - 261. Hale S. E, Hanley K., Lehmann J., Zimmerman A. R. & Cornelissen G. (2011). Effects of chemical, biological and physical aging as well as soil addition on the sorption of pyrene to activated carbon and biochar. Environmental Science and Technology 45: 10445- 10453 Hamer, U. & Marschner B. (2002). Priming effects of sugars, amino acids, organic acids and catechol on the mineralization of lignin and peat. Journal of Plant Nutrition and Soil Science. 165:261–268. Hardie, A. G., Botha, A., (2010). Biochar amendment of infertile Western Cape sandy soils: Implication for food security. Hope project. Hardie, M., Clothier, B., Bound, S., Oliver, G. & Close, D. (2014). Does biochar influence soil physical properties and soil availability? Internation Journal of Plant and Soil science. vol 6, 1- 5. Havlin, J. L., Beaton, J. D., Tisdale, S. L. & Nelson, W. L. (1999). Soil Fertility and Fertilizers: th Introduction to Nutrient Management. 6 edition, Prentice hall inc. Saddle River New Jersey. 73 University of Ghana http://ugspace.ug.edu.gh Heitkotter, J. & Marschner, B. (2015). Interactive effects of biochar ageing in soils related to feedstock, pyrolysis temperature, and historic charcoal production. Geoderma. 245–246, 56-64. Herath, H. M. S. K., Arbestain, M. C., & Hedley M. (2013). Effect of biochar on soil physical properties in two contrasting soils: An Alfisol and an Andisol. Geoderma. 209-210. pp. 188-197 Ibrahim, H. M., Al -Wabel, M. I., Usman, A. R. A. & Al-Omran, A. (2013). Effect of Conocarpus biochar application on the hydraulic properties of a sandy loam soil. Journal of Soil Science Society of America. 178,123-167 Irshad, M., Waseem, A., Umar, M. & Sabir, M. A. (2014). Leachability of Nitrate from Sandy Soil using Waste Amendments, Communications in Soil Science and Plant Analysis. 45:5, 680-687, DOI:10.1080/00103624.2013.867046. pp 69-83. Jalali, M., & Merrikhpour, H. (2006). Effects of poor quality irrigation waters on the nutrient leaching and groundwater quality from sandy soil. Journal of Environmental geology. 53: 1289–1298 DOI 10.1007/s 00254 - 007- 0735 – 5. Pp 105-139. Jaynes, D., Colvin, T., Karlen, D., Cambardella, C., & Meek, D. (2001). Nitrate loss in subsurface drainage as affected by nitrogen fertilizer rate. Journal of Environmental Quality. 30, 1305-1314. 74 University of Ghana http://ugspace.ug.edu.gh Kanthle, A. K., Lenka, N. K., Lenka, S. & Tedia, K. (2016). Biochar impact on nitrate leaching as influenced by native soil organic carbon in an Inceptisol of central India. Soil and Tillage Research. 157 (2016) 65–72 Kuppusamy, S., Thavamani, P., Megharaj, M., Venkateswarlu, K. & Naidu, R. (2016). Agronomic and remedial benefits and risks of applying biochar to soil: current knowledge and future research directions. Environ. Int. 87, 1–12 Karaca, S., Gurses, A., Ejder, M. & Acikyildiz M. (2004). Kinetic modeling of liquid phase adsorption of phosphate on dolomite. Journal of Colloid and Interface Science. 277:257–263. Karathanasis, A. D. (1999). „Subsurface migration of copper and zinc mediated by soil colloids‟, Soil Science Society of America Journal. Vol 63, 830–838 Keith, A., Singh, B. & Singh, B. P. (2011). Interactive priming of biochar and labile organic matter mineralization in a smectite-rich soil. Environmental Science and Technology. 45, 9611–9618. Khan, A., Munif, F., Akhtar, K., Afridi, M. Z., Zahoor Ahmad, Z., Fahad, S., Ullah, R., Khan, F. A. & Din M. (2014). Response of fodder maize to various levels of nitrogen and phosphorus. American Journal of Plant Sciences. 5, 2323-2329. Kizilkaya, R. & Hepşen, S. (2004). Effects of biosolid amendment on enzyme activities in earthworm (Lumbricusterrestris) casts. Journal of Plant Nutrition and Soil Science. 167: 202-208. 75 University of Ghana http://ugspace.ug.edu.gh Knowles, O. A., Robinson, B. H., Contangelo, A. & Clucas L. (2011). Biochar for mitigation of nitrate leaching from soil amended with biosolids. Science of the Total Environment. 4099. 3206-3210. Knox, E., Moody, D.W. (1991). Influence of hydrology, soil properties and agriculture land use on nitrogen in ground water. Soil Science of America Journal. 677. 157-199 Kongthod, T., Thanachit, S., Anusontpornperm, S. & Wiriyakitnateekul, W. (2015). Effects of Biochars and other Organic Soil Amendments on Plant Nutrient Availability in an Ustoxic Quartzipsamment. Pedosphere (15). Doi; 10.1016/s1002-0162. 121-131 Landon, J. R. (1991). Booker Tropical Soil Manual. A hand book for soil survey and agriculture land evaluation in the tropics and subtropics. Landon J.R. (eds). Booker Tale, Thame, Oxon, UK, pp 58-125. Liang, B., Lehmann, J., Solomon, D., Kinyangi, J., Grossman, J., O‟Neill, B., Skjemstad, J. O., Thies, J., Luizão, F. J., Petersen, J. and Neves, E. G. (2006). „Black carbon increases cation exchange capacity in soils‟, Soil Science Society of America Journal, vol 70, pp 1719-1730 Laird, D., Fleming, P., Wang, B. Q., Horton, R. & Karlen D. (2010). Biochar impact on nutrient leaching from a Midwestern agricultural soil. Geoderma. 158, 436 – 442. Lehmann, J., Rillig, M. C., Thies, J., Masiello, C. A., Hockaday, W. C. & Crowley, D. (2011). Biochar effects on soil biota: a review. Soil biology and Biochemistry. 43: 1812 – 1836. 76 University of Ghana http://ugspace.ug.edu.gh Lehmann, J., da Silva J. P., Rondon, M., da Silva, C. M., Greenwood J., Nehls T., Steiner C. & Glaser B. (2002). Slash-and-char: a feasible alternative for soil fertility management in the Central Amazon? Transaction World Congress Soil Science. 17: 1–12. Lehman J. & Schroth G. (2003). Subsoil root activity in tree-based cropping systems. Plant and Soil. 255: 319–331, 2003. Lehmann, J., Joseph, S. (2009). Biochar for Environmental Management: Science and Technology. Earthscan, London. 89 -107 Lehmann, J., da Silva Jr., J. P., Steiner, C., Nehls, T., Zech, W. & Glaser, B. (2003). Nutrient availability and leaching in an archaeological Anthrosol and a Ferralsol of the Central Amazon basin: Fertilizer, manure and charcoal amendments‟, International Journal of Plant and Soil Science. Vol 249, pp 343–357 Lehmann, J., Lilienfein, J., Rebel, K., do Carmo Lima, S., & Wilcke, W. (2004). Subsoil retention of organic and inorganic nitrogen in a Brazilian savanna Oxisol‟, Journal of Soil Use and Management. Vol 20, pp 163-172. Lehmann J., Gaunt J. & Rondon M. (2006). Biochar sequestration in terrestrial ecosystems – a review. Mitigation and Adaption Strategies for Global Change, 11: 395–419. Liang, B., Lehmann, J., Solomon, D., Kinyangi, J., Grossman, J., O‟Neill, B., Skjemstad, J. O., Thies, J., Luizão, F. J., Petersen, J. & Neves, E. G., (2006). „Black carbon increases cation exchange capacity in soils‟, Soil Science Society of America Journal. Vol 70, 1719–1730 77 University of Ghana http://ugspace.ug.edu.gh Liu, Y., Lu, H., Yang, S., & Wang, Y. (2016). Impacts of biochar addition on rice yield and soil properties in a cold waterlogged paddy for two crop seasons. Field Crops Research. http://dx.doi.org/10.1016/j.fcr.2016.03.003 Liu, X. H. & Zhang, X. C. (2012). Effect of Biochar on pH of Alkaline Soils in the Loess Plateau: Results from Incubation Experiments. International Journal of Agriculture and Biology 1814–9596 Lone, A. H., Najar, G. R., Ganie, M. A., Sofi, J. A. & Tahir Ali T. (2015). Biochar for sustainable soil health: a review of prospects and concerns. Pedosphere 25 (5), 639 – 653 Ma, Y. L., & Matsunaka T. (2013). Biochar derived from diary carcasses an alternative source of phosphorus and amendment for soil acidity. Journal of Soil Science and Nutrition. Vol 10, 120-137 Maesek, O., Brownsort, P., Cross, A. & Sohi, S. (2011). Influence of production conditions on the yield and environmental stability of biochar. Fuel Journal 103, 151–155 Major, J., Steiner, C., Downie, A. & Lehmann, J. (2009). Biochar effects on nutrient leaching. Biochar for environmental management. Earthscan: London. pp. 271-287. Major, J., Lehmann, J., Rondon, M. & Goodale, C. (2010). Fate of soil-applied black carbon: downward migration, leaching and soil respiration. Global Change Biology. 16, 1366– 1379. Marris, E. (2006). Putting the carbon back: black is the new green. Nature 442, 624– 626 78 University of Ghana http://ugspace.ug.edu.gh Marschner H. (1995). Mineral nutrition of higher plants. Annal of Botany, volume 78, issue 4, 527-528. Masiello, C. A. (2004). New directions in black carbon organic geochemistry. Mar. Chemosphere. 92, 201-213 Matson, P. A., Parton, W. J., Power, A. G. & Swift M. J. (1997). Agricultural intensification and Ecosystem Properties,” Science. 277: 504-509. McAllister, C. H., Beatty, P. H. & Good, A. G. (2012). Engineering nitrogen use efficient crop plants; the current status. Journal of Plant Biotechnology. 10 (11), 1467 –7652. McElligott, K. M., (2011). Biochar amendments to forest soils: effects on soil properties and tree growth . M. S. Thesis, University of Idaho, Moscow. Mohamed, B. A., Ellis, N., Kim, C. S., Bi X. & Emam A. (2016). Engineered biochar from microwave - assisted catalytic pyrolysis of switchgrass for increasing water-holding capacity and fertility of sandy soil. Science of the Total Environment. 566 -567: 387–397 Molner, M., Vaszita, E., Farkas, E., Ujaczki, E., Kertesz, I. F., Tolner, M., Klebercz, O., Kirchkeszner, C., Gruiz, K., Uzinger, N. & Feigl V. (2016). Acidic sandy soil improvement with biochar – A microcosm study. Science of the Total Environment. 1: 563 564: 855-65 Mukhejee, A., Lal, R., & Zimmerman A. R. (2014). Effects of biochar and other amendments on the physical properties and greenhouse gas emissions of an artificially degraded soil. Science of the Total Environment. 487, 26 -36 79 University of Ghana http://ugspace.ug.edu.gh Mukherjee, A., & Lal, R. (2013). Biochar impacts on soil physical properties and greenhouse gas emissions. Agronomy 3, 313–339. Nakamura, K., Harter, T., Hirono, Y., Horino, H., & Mitsuno T. (2004). Assessment of Root Zone Nitrogen Leaching as Affected by Irrigation and Nutrients Management practices. Nartey E. (1994). Pedogenic changes and phosphorus availability in some soils of Northern Ghana. M.phil Thesis in partial fulfillment of requirement for Master of philosophy degree in soil science University of Ghana, Legon, Accra. Nelissen, V., Rütting, T., Huygens, D., Staelens, J., Ruysschaert, G., & Boeckx, P. (2012). Maize biochars accelerate short-term soil nitrogen dynamics in a loamy sand soil. Soil Biology Biochemistry. 55, 20 – 27. Nigussie, A., Kissi E., Misganaw, M., Ambaw, G. (2012). Effect of Biochar Application on Soil Properties and Nutrient Uptake of Lettuces (Lactuca sativa) Grown in Chromium Polluted Soils. American Eurasian Journal of Agriculture and Environment. 12(3):269- 376, 2012 Novak, J. M., Busscher, W. J., Laird, D. L., Ahmedna, M., Watts, D. W. & Niandou, M. A. S. (2009). Impact of biochar amendment on fertility of a southeastern coastal plain soil. Journal of Soil Science. 174, 105–112. Novak, J. M., Busscher, W. J., Watts, D. W., Laird, D. A., Ahmedna, M. A., Niandou, M. A. S. (2010). Short-term CO2 mineralization after additions of biochar and switchgrass to a Typic Kandiudult. Geoderma 154: 281– 8. 80 University of Ghana http://ugspace.ug.edu.gh Novak, J. M., Cantrell, K. B., Watts, D. W. (2013). Compositional and thermal evaluation of lignocellulosic and poultry litter chars via high and low temperature pyrolysis. Bioenergy Research. 6, 114–130. Nguyen, H. Y. N. (2008). Effect of bio-char on the growth of maize (Zea mays) in two types of soil. Miniproject, Mekarn MSc 2008-10. http://mekarn.org/msc2008- 10/miniprojects/minpro/nhi01.htm Nyamangara, J., Bergstrom, L. F., Piha, M. I. & Giller, K. E. (2003). Fertilizer use efficiency and nitrate leaching in a tropical sandy soil. Journal of Environmental Quality, vol. 32, issue 2, 599-606. Obeng, H. (2000). Soil Classification in Ghana. Selected Economic Issues No.3 Obia, A., Mulder, J., Martisen, V., Cornelissen, G., Borresen, T. (2016). In situ effects of biochar on aggregation, water retention and porosity in light-textured tropical soils. Journal of Soil and Tillage Research. 155 (2016) 35 – 44. Ogbonnaya, U., & Semple, K. T. (2013). Impact of biochar on organic contaminants in soil: a tool for mitigating risk? Agronomy. 3, 349–375. Paramasivam, S., & Alva, A. K. (1997). Leaching of nitrogen forms from controlled‐release nitrogen fertilizers. Communications in Soil Science and Plant Analysis, 28:17-18, 1663- 1674, DOI: 10.1080/00103629709369906. 81 University of Ghana http://ugspace.ug.edu.gh Prendergast-Miller, M. T., Duvall, M. & Sohi S. P. (2014). Biochar-root interactions are mediated by biochar nutrient content and impacts on soil nutrient availability. European Journal of Soil Science 65, 173–185. Purankayastha, T. J., Das, K. C., Gaskin, J., Harris, K., & Smith J. L., Kumari S. (2016). Effect of pyrolysis temperatures on stability and priming effects of C3 and C4 biochars applied to two different soils. Journal of Soil and Tillage Research. 155: 107–115. Razzarque, A. H. M, & Hanafi M. M. (2005). Leaching of nitrogen in peat soil. Communication in Soil Science and Plant Science, 35:13-14, 1793-1799. Ren, X., Sun, H., Wang, F., & Cao, F. (2015). The changes in biochar properties and sorption capacities after being cultured with wheat for three months. Chemosphere 144, 2257- 2263 Revell, K. T., Maguire, R. O. & Agblevor, F. A. (2012). Influence of poultry litter biochar on soil properties and plant growth. Internal Journal of Soil science. 177, 402–408. Ribaudo, M., Delgado, J., Hansen, L., Livingstone, M., Mosheim, R., & Williamson, J. (2011). Nitrogen in Agricultural Systems: Implications for Conservation Policy. ERR - 127. U.S. Dept. of Agriculture, Econ. Res. Serv. September 2011. 115-145 Ronsse, F., Van Heckes, S., Dickson D., & Prins W. (2013). Production and characterization of slow pyrolysis biochar: influence of feedstock type and pyrolysis condition, Global Change Biology, Bioenergy 5: 104 -115. 82 University of Ghana http://ugspace.ug.edu.gh Rouquerol, F., Rouquerol, J., & Sing, K. (1999). “Adsorption by Powders and Porous Solids”, Academic Press, London (1999). th Russell, C. R. (1973). Industrial uses of corn starch. Paper presented at the 58 annual meeting of American Association of cereal chemist, November 4-8, 1973, St. Louis Missouri. Salem, S. A., & Ali, A. E. (1979). Effect of nitrogen fertilizer levels and varieties on grain yield and some plant characters of maize (Zea mays L.). Journal of Legume Research. 33 (2), 1035. SARI, 1996. Savanna Agricultural Research Institute. Annual Report. Schimmelpfennig, S., & Glaser, B. (2011). One step forward toward characterization: some important material properties to distinguish biochars. Journal of Environmental Quality 41, 1001–1013 Schroth, G., Rodrigues, M. R. L., & D Angelo S. A. (1999). Spatial patterns of nitrogen mineralization, fertilizer distribution and root explain nitrate leaching from mature Amazonian oil plantation. Journal of Soil Use and Management 16, 222-229 Shrestha J. (2014). Effect of nitrogen and plant population on flowering and grain yield of winter maize. Unique Research Journal of Agriculture Science. 2: 1–6 Shrestha, R. K., Cooperband, L.R. & MacGuidwin A. E. (2010). Strategies to reduce nitrate leaching into groundwater in potato grown in sandy soils: Case study from north central USA. American. pp 1-13 83 University of Ghana http://ugspace.ug.edu.gh Shrestha, G., Traina, S. J., & Swanston, C.W. (2010). Black carbon's properties and role in the environment: a comprehensive review. Sustainability 2, 294–320 Sigua, G. C., Novak, J. M., Watts, D. W., Johnson, M. G., & Spokas K. (2016). Efficacies of designer biochars in improving biomass and nutrient uptake of winter wheat grown in a hard setting subsoil layer. Chemosphere. vol 142. Pp. 176-183 Singh, B., Singh, B. P., & Cowie A. L. (2010). Characterisation and evaluation of biochars for their application as a soil amendment. International Journal of Soil Research. 48 (7), 516 -525 (2010) Sika, M. P. (2012). Effect of biochar on chemistry, nutrient uptake and fertilizer mobility in sandy soil. MSc Thesis in partial fulfillment of requirement for Master of Science degree in Agriculture University of Stellenbosch. Sika, M. P., & Hardie, A. G. (2014). Effect of pinewood biochar on ammonium nitrate leaching and availability in a South African sandy soil. European Journal of Soil Science. Vol, 65 issue 1, pp.113-119 Sitthaphanit S., Limpinuntana, V., Toomsan B., Panchaban S., & Bell R. W. (2009). Fertilizer strategies for improved nutrient use efficiency on sandy soils in high rainfall regimes. Journal of Nutrients Cycling Agroecosystems. 85: 123-139. Smith, R. A., Schwarz, G. E. & Alexander, R. B. (1997). “SPARROW Surface Water-Quality Modeling Nutrients in Watersheds of the Conterminous United States: Model Predictions for Total Nitrogen (TN) and Total Phosphorus (TP).” 84 University of Ghana http://ugspace.ug.edu.gh Sohi, S. P., Krull E., Lopez-Capel E. & Bol R. (2009). A review of biochar and its use and function in soil. Advance Agronony 105:47- 82. Sparks D. L. (2003). Environmental Soil Chemistry. Academic Press, London Spoka, K. A. (2010). Review of the stability of biochar in soils: predictability of O: C molar ratios. Carbon Management.1: 289-303. Steiner, C., Glaser, B., Teixeira, W. G., Lehmann, J., Blum, W. E. H. & Zech, W. (2008). Nitrogen retention and plant uptake on a highly weathered central Amazonian Ferralsol amended with compost and charcoal. Journal of Plant Nutrition & Soil Science. 171, 893–899. Sun, D., Meng, J. & Chen, W. (2013). Effects of abiotic components induced by biochar on microbial communities. Acta Agriculturae Scandinavica Section. B 63, 633–641. Sun, Y., Gao, B., Yao, Y., Fang, J., Zhang, M., Zhou, Y. & Chen H. (2014). Effects of feedstock type, production method, and pyrolysis temperature on biochar and hydrochar properties. Chemical Engineering Journal 240 (2014) 574 –578. Taghizadeh -Toosi, A., Clough, T., Sherlock, R. & Condron, L. (2012). Biochar adsorbed ammonia is bioavailable. Plant and Soil 350, 57-69. Taketani, R. G., Lima, A. B., Jesus, E. C., Teixeira, W. G., Tiedje, J. M. & Tsai, S. M. (2013). Bacterial community composition of anthropogenic biochar and Amazonian anthrosols assessed by 16S rRNA gene 454 pyrosequencing. Journal of Microbiology. 104, 233– 242 85 University of Ghana http://ugspace.ug.edu.gh Tong, H., Hu, M., Li, F. B., Liu, C. S. & Chen M. J. (2014). Biochar enhances the microbial and chemical transformation of pentachlorophenol in paddy Soil. Soil Biology and Biochemistry 70:142-150. Tryon E. H. (1948) „Effect of charcoal on certain physical, chemical, and biological properties of soils‟, Ecological Monographs, vol 18, pp 81–115. Uzoma, K. C., Inoue, M., Andry, H., Fujimaki, H., Zahoor, A. & Nishihara, E. (2011). Effect of cow manure biochar on maize productivity under sandy soil condition. Journal of Soil Use Management 27, 205–212. Uchimiya, M., Wartelle, L. H, Klasson, K. T., Fortier, C. A. & Lima I. M. (2011). Influence of pyrolysis temperature on biochar property and function as a heavy metal sorbent in soil, Journal of Agricultural and Food Chemistry. 59: 2501–2510. Vanlauwe, B., Diels, J., Aihou, K., Iwuafor, E. N. O., Lyasse, O., Sanginga, N. & Merckx R. (2002). Direct interactions between N fertilizer and organic matter: Evidence from trials with 15N-labelled fertilizer. In: Vanlauwe B, Diels J., Sanginga N., Merckx R. (eds). Integrated plant nutrient management in sub - Saharan Africa. pp 173-184. Van Zwieten, L., S., Kimber, S., Morris, K., Chan, A., Downie, J., Rust, S., Joseph S. & Cowie A. (2010). Effects of biochar from slow pyrolysis of papermill waste on agronomic performance and soil fertility. Journal of Plant and Soil Analysis, 327: 235–246 86 University of Ghana http://ugspace.ug.edu.gh Van Zwieten L., Kimber S., Downie A., Morris S., Petty S., Rust J. & Chan K.Y. (2010b). A glasshouse study on the interaction of low mineral ash biochar with nitrogen in a sandy soil. Australian Journal of Soil Research, 48: 569–576. Ventura, M., Sorrenti, G., Panzacchi, P., George, E. & Tonon, G. (2013). Biochar Reduces Short-Term Nitrate Leaching from A Horizon in an Apple Orchard. Journal of Environmental Quality 42, 76 – 82 Vitousek, P. M., Aber, J. D., Howarth, R. W., Likens, G. E., Matson, P. A, Schindler, D. W., Schlesinger, W. H & Tilman D., G. (1997). “Human Alteration of the Global Nitrogen Cycle: Sources and Consequences,” Ecological Applications. 73 (3):737-750. Wadowati, W. & Asnah A. (2014). Biochar effect at potassium fertilizer and dosage leaching potassium for two – corn planting season. Integrated Plant Nutrient Management in Sub Saharan - Africa. pp 191-284. Walkley, A. & Black, T. A. (1934). An examination of the Degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration method. Soil Science., 37:29–38. Watanabe, F. S. and Olsen, S. R. (1965) Test of an ascorbic acid method for determining phosphorus in water and NaHCO3 extracts from soil. Soil Science Society of America Proceedings, 29: 677–678. Wang, X. R, Zhou, W., Liang, G., Song, D. & Zhang X. (2015). Characteristics of maize biochar with different pyrolysis temperatures and its effects on organic carbon, nitrogen and 87 University of Ghana http://ugspace.ug.edu.gh enzymatic activities after addition to fluvo-aquic soil. Science of the Total Environment. Vol 538 : pp 137-144. Wang, X. R., Cook, S., Tao, S., Xing, B. (2007). Sorption of organic contaminants by biopolymers. Chemosphere. 6 : 1476-1484. Watzinger, A., Feichtmaira, S., Kitzlerc B., Zehetnerb, F., Kloss, S., Wimmera, B., Zechmeister- Boltenstern, S. & Sojaa G. (2014). Soil microbial communities responded to biochar application in temperate soils and slowly metabolized 13C-labelled biochar as revealed by 13C PLFA analyses: results from a short-term incubation and pot experiment. European Journal of Soil Science 65, 40–51 DOI: 10.1111/ejss.12100. White, P. F., Oberthur, T. & Pheav, S. (1997). The soil used for rice production in Cambodia. Manual for recognition and management. International Rice Research Institute Manila, Philippines. Wu, H. W., Yip, K., Kong, Z. Y., Li, C. Z., Liu, D. W., Yu, Y. & Gao X. P. ( 2011). Removal and recycling of inherent inorganic nutrient species in mallee biomass and derived biochars by water leaching. Industrial and Engineering Chemistry Research. 50: 12143 –12151. Xu, N., Tan, G., Wang, H. & Gai, X. (2016). Effect of biochar additions to soil on nitrogen leaching, microbial biomass and bacterial community structure. European Journal of Soil Biology 74, 1-8 88 University of Ghana http://ugspace.ug.edu.gh Yao Y., Gao B., Zhang M., Inyang M. & Zimmerman A. R. (2012). Effect of biochar amendment on sorption and leaching of nitrate, ammonium, and phosphate in a sandy soil. Chemosphere. volume 89, issue 11, 1467-1471. Yoo, G., Kim, H., Chen, J. & Kim Y. (2014). Effects of biochar addition on nitrogenleaching and soil structure following fertilizer application to rice paddy soil. Soil Science Society of America Journal. 78, 852-860. Yuan, J. H., Xu, R. K. & Zhang, H. (2016). The forms of alkalis in the biochar produced from crop residues at different temperatures. Bioresource Technology. 102, 3488–3497. Yuan, J. & Xu R. (2011). The amelioration effects of low temperature biochar generated from nine crop residues on an acidic ultisol. Journal of Soil Use Management. 27: 110–115. Yu, O. Y., Raiche, B. & Sinks, S. (2013). Impact of biochar on the water holding capacity of loamy sand soil. International Journal of Energy and Environmental Engineering. 4: 44- 65. Zavalloni, C., Alberti, G., Biasiol, S., Vedove, G. D., Fornasier, F., Liu, J. & Peressotti, A. (2011). Microbial mineralization of biochar and wheat straw mixture in soil: a short-term study. Applied Soil Ecology. 50, 45–51. Zolue A. (2010). Characterization of physical and chemical properties of different biochar. MSc Thesis in partial fulfillment of requirement for Master of Agriculture degree University of Ghana. 89 University of Ghana http://ugspace.ug.edu.gh Zhan, Q. Z., Dijkstra, F. A., Liu, X. R., Wang, Y. D., Huang, J. (2014). Effects of biochar on soil microbial biomass after four years of consecutive application in North China Plains. PLos one 9 (7):e102062 DOI:10.1371/journal.pone.0102062 Zhang, A. F., Liu, Y. M., Pan G. X., Hussain, Q., Li, L. Q., Zheng, J. W. & Zhang X. H. (2011). Effect of biochar amendment on maize yield and greenhouse gas emissions from a soil organic carbon poor calcareous loamy soil from Central China Plain. Plant and Soil, 351: 263-27 Zhang, J. & You, C. (2013). Water holding capacity and absorption properties of wood chars. Energy Fuel 27, 2643–2648 http://dx.doi.org/10.1021/ef4000769 Zhang X. K., Sarmah A. K., Bokan N. S., He L. Z., Lin X. M., Che L., Tang C. X. & Wang H. L. (2016). Effect of aging process on adsorption of diethyl phthalate in soils amended with bamboo biochars. Chemosphere. 142:28–34 Zhao, X., Yan X., Wang S., Xing. G. & Yang Zhou Y. (2013). Effects of the addition of rice- straw-based biochar on leaching and retention of fertilizer N in highly fertilized cropland soil. Soil Science and Plant Nutrition 59:5, 771-782 Zhao, X., Wang, J., Xu, H., Zhou, C., Wang, S. & Xing G. (2014). Effects of crop-straw biochar on crop growth and soil fertility over a wheat-millet rotation in soils of China. Journal of Soil Use Management. 30, 311–319. 90 University of Ghana http://ugspace.ug.edu.gh Zhao, R., Coles, N., Kong, Z. & Wu, J. (2013). Effects of aged and fresh biochars on soil acidity under different incubation conditions. Journal of Soil tillage and Research 146: 133– 138. Zhu, A. N., Zhang, J. B., Zhao, B. Z., Cheng, Z. H. & Li L. P. (2005). Water balance and nitrate leaching losses under intensive crop production with Ochric Aquic Cambosols in North China Plain. International Journal of Environment 31: 904–912. Ziblim, I. A., Anti, D. O. & Asmah E. A. (2012). Productivity index and rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Journal of Soil Science and Environmental Management vol (36), pp. 154- 163 Zimmerman, A. R., Gao, B. & Ahn, M. Y. (2011). Positive and negative carbon mineralization priming effects among a variety of biochar amended soils. Jounal of Soil Biology and Biochemistry, vol 43 (6) 1169-1179 Zimmerman, A. R. (2010). Abiotic and Microbial oxidation of laboratory produced Black carbon (Biochar). Environmental Science and Technology 44 (4): 1295-1301 Zotarelli, L., Scholberg, J. M., Dukes, M. D. & Carpena R. M. (2007). Monitoring of nitrate leaching in sandy soils: Comparison of three methods. Journal of Environmental Quality. 36:953-962 91 University of Ghana http://ugspace.ug.edu.gh APPENDIX th Variate: Amount of NH4-N in leachate collected on 14 day after planting (first planting) Source of variation d.f s.s m.s v.r F pr. Fertilizer 3 1.0249 0.3416 0.46 0.709 Soil 1 781.2183 781.2183 1058.49 <.001 Feedstock 4 2694.3569 673.5892 912.66 <.001 Fertilizer.Soil 3 2.2768 0.7589 1.03 0.385 Fertilizer.Feedstock 12 2.8933 0.2411 0.33 0.982 Soil.Feedstock 4 263.3534 65.8384 89.21 <.001 Fertilizer.Soil.Feedstock 12 4.4374 0.3698 0.50 0.908 Residual 80 59.0441 0.7381 Total 119 3808.6052 LSD = 1.3959 CV= 14.0% th Variate: Amount of NH4-N in leachate collected on 28 day after planting (first planting) Source of variation d.f s.s m.s v.r F.pr Fertilizer 3 1.7235 0.5745 1.24 0.300 Soil 1 286.6284 286.6284 619.52 <.001 Feedstock 4 1597.6606 399.4151 863.29 <.001 Fertilizer.Soil 3 1.3125 0.4375 0.95 0.423 Fertilizer.Feedstock 12 3.0907 0.2576 0.56 0.870 Soil.Feedstock 4 173.0720 43.2680 93.52 <.001 Fertilizer.Soil.Feedstock 12 2.3436 0.1953 0.42 0.950 Residual 80 37.0133 0.4627 Total 119 2102.8445 LSD = 1.1052 CV = 15.0% 92 University of Ghana http://ugspace.ug.edu.gh th Variate: Amount of NO3-N in leachate collected on 14 day after planting (first planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer 3 0.2073 0.0691 0.12 0.948 Soil 1 32.2196 32.2196 56.02 <.001 Feedstock_rate 4 489.5553 122.3888 212.81 <.001 Fertilizer.Soil 3 0.7876 0.2625 0.46 0.713 Fertilizer.Feedstock_rate 12 6.9331 0.5778 1.00 0.453 Soil.Feedstock_rate 4 32.7644 8.1911 14.24 <.001 Fertilizer.Soil.Feedstock_rate 12 2.6896 0.2241 0.39 0.964 Residual 80 46.0083 0.5751 Total 119 611.1652 LSD = 1.23 CV = 23.8% th Variate: Amount of NO3-N in leachate collected on 28 day after planting (first planting) Source of variation d.f s.s m.s v.r F.pr Fertilizer 3 0.0590 0.0197 0.12 0.948 Soil 1 40.1016 40.1016 246.07 <.001 Feedstock_rate 4 423.6215 105.9054 649.84 <.001 Fertilizer.Soil 3 0.1518 0.0506 0.31 0.818 Fertilizer.Feedstock_rate 12 0.3026 0.0252 0.15 0.999 Soil.Feedstock_rate 4 61.3805 15.3451 94.16 <.001 Fertilizer.Soil.Feedstock_rate 12 0.2971 0.0248 0.15 1.000 Residual 80 13.0377 0.1630 Total 119 538.9519 LSD = 0.65 CV = 27.5% 93 University of Ghana http://ugspace.ug.edu.gh th Variate: Amount of NH4-N in leachate collected on 14 day after planting (Second planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer 3 0.5015 0.1672 0.58 0.630 Soil 1 14.2279 14.2279 49.30 <.001 Feedstock 4 486.3668 121.5917 421.28 <.001 Fertilizer.Soil 3 0.6643 0.2214 0.77 0.516 Fertilizer.Feedstock 12 1.5400 0.1283 0.44 0.940 Soil.Feedstock 4 34.6601 8.6650 30.02 <.001 Fertilizer.Soil.Feedstock 12 2.1209 0.1767 0.61 0.826 Residual 80 23.0899 0.2886 Total 119 563.1713 LSD = 0.87 CV = 18.34% th Variate: Amount of NH4-N in leachate collected on 28 day after planting (Second planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer 3 0.07824 0.02608 0.47 0.702 Soil 1 6.43570 6.43570 116.67 <.001 Feedstock 4 107.09395 26.77349 485.38 <.001 Fertilizer.Soil 3 0.12682 0.04227 0.77 0.516 Fertilizer.Feedstock 12 0.27335 0.02278 0.41 0.954 Soil.Feedstock 4 27.97715 6.99429 126.80 <.001 Fertilizer.Soil.Feedstock 12 0.33975 0.02831 0.51 0.900 Residual 80 4.41280 0.05516 Total 119 146.73776 LSD = 0.3816 CV = 24.3% 94 University of Ghana http://ugspace.ug.edu.gh th Variate: Amount of NO3-N in leachate collected on 14 day after planting (Second planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer 3 0.11423 0.03808 0.41 0.749 Soil 1 3.75594 3.75594 40.12 <.001 Feedstock 4 116.82377 29.20594 311.94 <.001 Fertilizer.Soil 3 0.00770 0.00257 0.03 0.994 Fertilizer.Feedstock 12 0.10352 0.00863 0.09 1.000 Soil.Feedstock 4 15.52843 3.88211 41.46 <.001 Fertilizer.Soil.Feedstock 12 0.12928 0.01077 0.12 1.000 Residual 80 7.49013 0.09363 Total 119 143.95300 LSD = 0.49 CV = 31.4% th Variate: Amount of NO3-N in leachate collected on 28 day after planting (Second planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer 3 0.08605 0.02868 0.30 0.828 Soil 1 4.39301 4.39301 45.45 <.001 Feedstock 4 127.73919 31.93480 330.43 <.001 Fertilizer.Soil 3 0.04362 0.01454 0.15 0.929 Fertilizer.Feedstock 12 0.12955 0.01080 0.11 1.000 Soil.Feedstock 4 24.13389 6.03347 62.43 <.001 Fertilizer.Soil.Feedstock 12 0.39061 0.03255 0.34 0.980 Residual 80 7.73167 0.09665 Total 119 164.64759 LSD = 0.51 CV = 29.2% 95 University of Ghana http://ugspace.ug.edu.gh Variate: N uptake in maize (first planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer_type 3 859.24 286.41 3.23 0.027 Soil 1 394.80 394.80 4.46 0.038 Feedstock 4 96452.49 24113.12 272.22 <.001 Fertilizer_type.Soil 3 387.41 129.14 1.46 0.232 Fertilizer_type.Feedstock 12 487.83 40.65 0.46 0.933 Soil.Feedstock 4 669.40 167.35 1.89 0.120 Fertilizer_type.Soil.Feedstock 12 846.43 70.54 0.80 0.653 Residual 80 7086.35 88.58 Total 119 107183.96 LSD = 15.29 CV = 14.9% Variate: N uptake in maize (Second planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer_type 3 5602.66 1867.55 19.56 <.001 Soil 1 3285.80 3285.80 34.41 <.001 Feedstock 4 55140.76 13785.19 144.35 <.001 Fertilizer_type.Soil 3 1953.32 651.11 6.82 <.001 Fertilizer_type.Feedstock 12 3560.65 296.72 3.11 0.001 Soil.Feedstock 4 1991.33 497.83 5.21 <.001 Fertilizer_type.Soil.Feedstock 12 3287.98 274.00 2.87 0.002 Residual 80 7640.06 95.50 Total 119 82462.56 LSD = 15.87 CV = 21.87 96 University of Ghana http://ugspace.ug.edu.gh Variate: NH4-N content in residual soil (first planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer 3 7.12 2.37 0.10 0.962 Soil 1 36713.61 36713.61 1481.03 <.001 Feedstock 4 47840.28 11960.07 482.47 <.001 Fertilizer.Soil 3 21.78 7.26 0.29 0.830 Fertilizer.Feedstock 12 92.56 7.71 0.31 0.986 Soil.Feedstock 4 2089.67 522.42 21.07 <.001 Fertilizer.Soil.Feedstock 12 71.34 5.94 0.24 0.996 Residual 80 1983.14 24.79 Total 119 88819.50 LSD = 8.09 CV = 7.6% Variate NO3-N content in residual soil (First planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer 3 188.509 62.836 7.95 <.001 soil 1 2905.063 2905.063 367.61 <.001 Feedstock 4 12482.262 3120.565 394.88 <.001 Fertilizer.soil 3 71.826 23.942 3.03 0.034 Fertilizer.Feedstock 12 94.170 7.848 0.99 0.463 soil.Feedstock 4 55.871 13.968 1.77 0.144 Fertilizer.soil.Feedstock 12 155.723 12.977 1.64 0.097 Residual 80 632.211 7.903 Total 119 16585.634 LSD = 4.56 CV = 6.3% 97 University of Ghana http://ugspace.ug.edu.gh Variate NH4-N content in residual soil (Second planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer 3 49.43 16.48 0.70 0.555 Soil 1 10696.28 10696.28 454.67 <.001 Feedstock 4 21378.69 5344.67 227.19 <.001 Fertilizer.Soil 3 22.99 7.66 0.33 0.807 Fertilizer.Feedstock 12 120.80 10.07 0.43 0.948 Soil.Feedstock 4 416.61 104.15 4.43 0.003 Fertilizer.Soil.Feedstock 12 229.86 19.15 0.81 0.635 Residual 80 1882.01 23.53 Total 119 34796.67 LSD = 7.88 CV = 12.7% Variate NO3-N content in residual soil (Second planting) Source of variation d.f. s.s. m.s. v.r. F pr. Fertilizer 3 15.351 5.117 2.28 0.086 soil 1 3210.157 3210.157 1431.08 <.001 Feedstock 4 3952.584 988.146 440.51 <.001 Fertilizer.soil 3 26.646 8.882 3.96 0.011 Fertilizer.Feedstock 12 27.002 2.250 1.00 0.454 soil.Feedstock 4 517.919 129.480 57.72 <.001 Fertilizer.soil.Feedstock 12 10.277 0.856 0.38 0.966 Residual 80 179.454 2.243 Total 119 7939.390 LSD = 2.42 CV= 7.8% 98