Browsing by Author "Adiku, S."
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Item Author Correction: Effects of biochar, waste water irrigation and fertilization on soil properties in West African urban agriculture (Scientific Reports (2017) DOI: 10.1038/s41598-017-10718-y)(Nature Publishing Group, 2018) Häring, V.; Manka'Abusi, D.; Akoto-Danso, E.K.; Werner, S.; Atiah, K.; Steiner, C.; Lompo, D.J.P.; Adiku, S.; Buerkert, A.; Marschner, B.This Article contains errors in Figures 1, 4, 5, 7, 8 and 9, where the keys were omitted. The correct Figures 1, 4, 5, 7, 8 and 9 appear below as Figures 1, 2, 3, 4, 5 and 6 respectively. (Figure Presented). © 2018 The Author(s).Item Conceptual methodologies in agro-environmental systems(Soil and Tillage Research, 2001-03) Rose, C.W.; Adiku, S.When continuous measurement of relevant above- and below-ground environmental factors is made, and the dynamics of crop growth and phenology is followed, it is shown that small-plot agronomic experimentation can provide information vital to the development and testing of simulation models. Such models for crops of maize (Zea mays) and the legume cowpea (Vigna unguiculata), grown as sole crops and in an intercrop system, were used to simulate yield at two separate sites in the main savanna farming zones in Ghana, West Africa. Simulation was carried out for these three cropping systems using 20 years of historical rainfall data for the two sites, investigating the effect on yield of management options which included time of planting, rate of nitrogen fertilizer application, and crop planting density. The yield results of this series of simulations were then subject to two different types of analysis in order to assist the evaluation of agricultural options for the nation. The first analysis was an economic evaluation based on gross margins, but using the stochastic-dominance technique to rank the profitability of the alternative cropping and management systems. The second, more general methodology employed was multi-criteria analysis (MCA). This analysis covered economic returns and their variability, the amount and quality of residue returned to the soil, and the aerial cover provided by the crop. Other factors which could affect the sustainability of production in the long term, but which could only be evaluated qualitatively, were also included in the analysis, as allowed in MCA methodology. The MCA was then carried out for three scenarios in which different weightings were given to economic outcomes and to factors which are believed to encourage ecological sustainability. These scenarios allow recognition of different priorities which might be given by traditional subsistence farmers as compared to commercial producers. Outcomes of this broad analysis of development alternatives provided scientific support for the traditional Ghanaian practice of grain/legume intercropping which is also widespread in the tropics. The suite of methodologies illustrated by the case study appears to be suitable for the evaluation of alternative farming systems at the scale of a small nation such as Ghana. © 2001 Elsevier Science B.V.Item Considering effective adaptation options to impacts of climate change for maize production in Ghana(Environmental Development, 2013-01) Tachie-Obeng, E.; Akponikpè, P.B.I.; Adiku, S.As a contribution to guide policy planning, effective climate change adaptation options to enhance maize production in Ghana were examined. The Agricultural Production Systems Simulator crop model, coupled with statistical downscaled climate scenarios of 9 general circulation models (GCMs) and farmer practices, were used to device adaptation options in the near future (NF) period of 2046-2065 based on IPCC A2 emission scenario at local scale level in Wa and Wenchi agricultural areas of Ghana. Results from the single-maize cropping season at Wa, in the savanna zone indicate that, a 6-week delay in sowing from 1961 to 2000 baseline date of 1st May to 15th June, was the most appropriate way to offset the negative effects of potential climate change resulting in a yield increase of 8.2%. In the forest-savanna transitional zone of Wenchi, a 4-week delay in the major season sowing date from 15th March to 15th April and no change in the minor season sowing date of 15th August resulted in a slight yield increase of 3.9%. On the other hand, a second adaptation option of using a medium heat-tolerant maize variety produced substantial gains in crop yield of 30.1% and 30.5% in savanna and forest-savanna transitional zones respectively with a longer grain-formation period under NF climate change when compared to delaying sowing dates. Effective adaptation options can thus reduce negative impacts of climate change in the NF, but require enabling policy to support its implementation. © 2012 Elsevier B.V.Item Influence of method of residue application and moisture content on water soluble nitrogen in a rhodickandiustalf amended with different fallow plant materials(West African Journal of Applied Ecology, 2019-10-05) Darko, D.A.; Nartey, E.K.; Adiku, S.; Laryea, K.B.Use of plant residues as nutrient sources presents a viable option to resource poor farmers who sparsely use mineral fertilizer in crop production. A study was conducted to gain an insight into how different application methods of residues from different fallow management systems under two moisture regimes would affect soluble N release in a Rhodic Kandiustalf. Three residue types viz, elephant grass from a natural fallow (T1) and another as a fallow following a previously fertilized maize (T2) and a fallow legume (T3) were surface applied and incorporated in a Rhodic Kandiustalf at both field capacity (FC) and 60% field capacity over a sixteen-week period. Incorporation of mucuna residues and elephant grass from previously fertilized maize fallow released similar soluble N levels which were higher than levels from the natural elephant grass amendments. At 60% FC, both mucuna and elephant grass from the fertilized maize fields that were surface applied had slower N releases than the grass from the natural fallow, suggesting the elephant grass from the natural fallow field could be used as an N source amidst light watering to avoid leaching in the dry season.Item Influences of changing land use and CO2 concentration on ecosystem and landscape level carbon and water balances in mountainous terrain of the Stubai Valley, Austria(Global and Planetary Change, 2009-05) Tenhunen, J.; Geyer, R.; Adiku, S.; Reichstein, M.; Tappeiner, U.; Bahn, M.; Cernusca, A.et.al.A process-based spatial simulation model was used to estimate gross primary production, ecosystem respiration, net ecosystem CO2 exchange and water use by the vegetation in Stubai Valley, Austria at landscape scale. The simulations were run for individual years from early spring to late fall, providing estimates in grasslands for carbon gain, biomass and leaf area development, allocation of photoproducts to the below ground ecosystem compartment, and water use. In the case of evergreen coniferous forests, gas exchange is estimated, but spatial simulation of growth over the single annual cycles is not included. Spatial parameterization of the model is derived for forest LAI based on remote sensing, for soil characteristics by generalization from spatial surveys and for climate drivers from observations at monitoring stations along the elevation gradient and from modelling of incident radiation in complex terrain. Validation of the model was carried out at point scale, and was based on comparison of model output at selected locations with observations along elevation gradients in Stubai Valley and Berchtesgaden National Park, Germany as well as with known trends in ecosystem response documented in the literature. The utility of the model for describing long-term changes in carbon and water balances at landscape scale is demonstrated in the context of land use change that occurred between 1861 and 2002 in Stubai Valley. During this period, coniferous forest increased in extent by ca. 11% of the vegetated area of 1861, primarily in the subalpine zone. Managed grassland decreased by 46%, while abandoned grassland and natural alpine mats increased by 14 and 11%, respectively. At point scale, the formulated model predicts higher canopy conductance in 1861 due to lower atmospheric CO2 concentration which opens stomata. As a result, water use at point scale decreased by ca. 8% in 2002 in the valley bottoms versus 10% at tree line. At landscape level, the decrease in water use by vegetation in 2002 was predicted to be twice as high (ca. 17%) due to increase in subalpine forest, reduction of managed grassland in the valley and on slopes, as well as abandonment of grassland which results in natural succession. Net ecosystem CO2 exchange (NEE) was predicted to increase (become more negative) at point scale depending on vegetation type by 10 to 20% in 2002 due to increasing atmospheric CO2 concentration. However, due to the shift from grassland to forest and natural vegetation, landscape level CO2 exchange did not change. As a result of land use change, the export of carbon in harvested biomass in 2002 was estimated at only 30% of that in 1861. While the need for further validation of model assumptions is recognized, especially changes in ecosystem behavior with changing atmospheric CO2 concentration, the model analysis indicates a long-term reduction in water use by vegetation and a shift in ecosystem services. The results provide a case study, where land use change may compensate or override the influences of increasing atmospheric CO2 concentration, maintaining a relatively constant NEE in present time period simulations as compared to 1861, as well as reducing export of carbon from the alpine landscape of Stubai Valley. Use of the model in evaluation of scenarios of future land use change and in relation to vulnerability of ecosystem services are discussed. © 2009 Elsevier B.V. All rights reserved.Item Physiological and morphological responses to water stress in two Acacia species from contrasting habitats(Tree Physiology, 2005-03) Otieno, D.O.; Schmidt, M.W.T.; Adiku, S.; Tenhunen, J.Container-grown seedlings of Acacia tortilis Forsk. Hayne and A. xanthophloea Benth. were watered either every other day (well watered) or every 7 days (water-stressed) for 1 year in a greenhouse. Total plant dry mass (T dm), carbon allocation and water relations were measured monthly. Differences in leaf area (LA) accounted for differences in Tdm between the species, and between well-watered and water-stressed plants. Reduction in LA as a result of water stress was attributed to reduced leaf initiation, leaf growth rate and leaf size. When subjected to prolonged water stress, Acacia xanthophloea wilted more rapidly than A. tortilis and, unlike A. tortilis, lost both leaves and branches. These differences between species were attributed to differences in the allocation of carbon between leaves and roots and in the ability to adjust osmotically. Rapid recovery in A. xanthophloea following the prolonged water-stress treatment was attributed to high cell wall elasticity. Previous exposure to water stress contributed to water-stress resistance and improved recovery after stress. © 2005 Heron Publishing - Victoria, Canada.