Management Practices Of Major Agricultural Wastes And Their Impact On Decomposition And Mineralization: A Case Study Of Kwaebibirem District Ghana
Date
2022-08
Authors
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Publisher
University of Ghana
Abstract
Significant quantities of agricultural and agro-industrial wastes are produced annually. Improper management of these wastes poses environmental problems such as surface and ground water pollution and air pollution among others. Managing agricultural wastes aim at maximizing economic benefits from the waste resources with affordable, suitable and environmental friendly systems. The aim of this study was to assess the current management practices of major agricultural wastes generated and evaluate the impact of some of these wastes on decomposition, mineralization as well as carbon dioxide and ammonia emissions. Questionnaires were administered to 175 farmers from five communities in the Kwaebibirem District. Five laboratory experiments were also conducted; effect of organic residue type and particle size on CO2 emission was investigated during 120 days; effect of organic residue type and particle size on decomposition and nutrient release patterns were evaluated during 22 weeks; CO2 and NH3 emissions from poultry droppings as affected by biochar application at different pH and rates were separately assessed during 30 days and the effect of biochar application to poultry droppings on nutrients release was assessed during 30 days. The findings of the study indicated that the major agricultural wastes of concern generated in the Kwaebibirem District were crop residues and animal wastes. The most crop residues generated were cocoa pod husks (CPH); various wastes from palm fruits, mainly empty fruit bunches (EFB); rice husks (RH) and straws and corn stalks. Animal wastes generated were predominantly poultry droppings (PD). The results indicated that the farmers have inadequate knowledge on the sustainable management of agricultural wastes and their uses in terms of soil fertility improvement. It is also revealed that farmers perceive weakly in animal manure use in soil fertility improvement. The results indicated that the cumulative CO2 emissions of EFB and CPH were not statistically different except for the smallest particle sizes, CPHS3 significantly emitted higher CO2 than EFBS3. The particle size of EFB and CPH significantly affected the cumulative CO2 emission. The cumulative CO2 emissions from EFB increased in the order of EFBS1<EFBS2< EFBS3 and their corresponding average cumulative CO2 emitted was 310.95, 326.04 and 350.70 mg CO2/g residue, respectively. The cumulative CO2 emissions from CPH increased in the order of CPHS1<CPHS2< CPHS3 and their corresponding average cumulative CO2 emitted was 313.55, 337.73 and 366.04 mg CO2/g residue, respectively. Results showed that CPH decomposed faster than EFB throughout the incubation period even if the difference was not statistically significant. The nutrients in EFB and CPH particle sizes were released in the order K> Ca > P = N at different rates. There was no significant difference in N and P release in EFB and CPH. CPH released K and Ca faster than EFB of the same particle size. Particle size of each of EFB and CPH did not show significance difference in release nutrients at the end of incubation period except for P release in CPH, where CPHS3 released significantly higher amount of P than CPHS1 and CPHS2. Results showed that irrespective of biochar rates and pH, mixing of biochar and poultry droppings resulted in a highly significant reduction (p<0.001) of CO2 and NH3 emissions. Biochar was effective in reducing over 30% of CO2 and 20% of NH3 emitted by poultry droppings alone. Biochar at pH6 was most effective in reducing CO2 and NH3 emissions. It was indicated that application of biochar to poultry droppings reduced nutrients release rate. The study highly recommends education and the trainings for the farmers on the impact of agro industrial wastes to the environment, affordable and environmental friendly management practices. Both EFB and CPH are suited for soil organic matter build-up and chopping the residues in small particle sizes is advised for short term fertility purpose. Biochar should be added to poultry droppings to retain nutrients, reduce carbon dioxide and ammonia gases emissions as a waste management strategy to reduce as well.
Description
MPhil. Environmental Science Degree Institute For Environment And Sanitation Studies.
Keywords
Agricultural Wastes, Decomposition, Mineralization, Kwaebibirem, Ghana