Evaluating the Impact of Organic Fertilizers on Maize Yield and Soil Health

Thesis Abstract

The persistent reliance on chemical fertilizers in maize cultivation has raised concerns over soil degradation, environmental sustainability, and diminishing yields, prompting the exploration of organic fertilizers as eco-friendly alternatives. This study examines the impact of organic fertilizers on maize yield and soil health, aiming to provide empirical evidence to inform sustainable agricultural practices. The specific objectives are to evaluate the effects of different types and application rates of organic fertilizers on maize productivity, to assess changes in soil physicochemical properties and microbial activity, and to compare the performance of organic fertilizers with conventional chemical fertilizers in promoting sustainable soil management. The research adopts a randomized complete block design (RCBD) in a field experiment conducted over two cropping seasons at a representative maize farm located in the midwestern region. The study population comprises smallholder maize farmers, with a total sample size of 120 plots, allocated into four treatment groups control (no fertilizer), chemical fertilizer application, animal manure, and composted plant residues, each replicated in five blocks. Data collection instruments include soil sampling kits, yield measurement tools, and structured questionnaires for qualitative insights. Soil samples are analyzed for physical and chemical parameters—such as pH, organic carbon, nitrogen, phosphorus, and cation exchange capacity—using standard laboratory techniques, while microbial activity is assessed via microbial biomass carbon and enzyme activities through spectrophotometric assays. Maize yield is measured at harvest, and data are analyzed using analysis of variance (ANOVA) to determine significant differences among treatments at a 5% significance level. Regression analysis explores the relationships between soil health indicators and maize yield, guided by the resource-based view theory and the soil health concept, emphasizing the importance of organic matter in sustainable production systems. It is anticipated that organic fertilizer treatments, particularly composted plant residues, will significantly enhance maize yield compared to control and will improve key soil health indicators over chemical fertilizers and untreated plots. Enhanced microbial biomass and activity are expected to correlate positively with crop productivity, supporting the hypothesis that organic amendments foster a resilient soil ecosystem. These findings will contribute to the growing body of evidence on organic fertilization as a viable strategy for sustainable maize production, emphasizing soil microbial health and nutrient cycling. The study highlights the potential of organic fertilizers to restore degraded soils, increase crop yields, and reduce dependency on chemical inputs, thereby promoting ecological intensification of maize farming systems. The main conclusion underscores the superiority of organic amendments in improving soil health and productivity, advocating for integrated nutrient management practices tailored to smallholder farmers' contexts. Recommendations include the adoption of composted plant residues and animal manure as sustainable fertilizer options, the refinement of application rates based on soil tests, and policy support for organic farming incentives. The study also suggests avenues for future research, particularly long-term assessments of organic fertilizers on soil resilience and climate change adaptation strategies in maize cultivation. Overall, the research advances understanding of organic fertilizer efficacy in improving both crop yields and soil ecosystem functions, aligning agricultural productivity with environmental sustainability objectives.