Design and evaluate biochar-integrated soil amendment for crop productivity

Thesis Abstract

The increasing demand for sustainable agricultural practices necessitates the development of soil amendments that enhance crop productivity while mitigating environmental impacts. This study addresses the critical challenge of low soil fertility and degraded soil health by exploring the design and evaluation of biochar-integrated soil amendments tailored to improve crop yields. The primary aim is to develop an optimized biochar-based soil amendment and rigorously assess its effectiveness on crop productivity, soil chemical and biological properties, and nutrient use efficiency. Specific objectives include (1) to produce biochar from locally available agricultural waste via pyrolysis at 500°C; (2) to formulate various biochar-based amendments with different dosage levels; (3) to evaluate their effects on soil nutrient dynamics, pH, and microbial activity; and (4) to determine the influence of these amendments on crop growth, yield, and nutrient uptake in maize cultivation. Employing a randomized complete block design (RCBD), the research involves conducting field experiments on a representative farm with a soil profile characterized by low organic matter and deficient nutrient levels. The study sample comprises three treatment groups—control (no amendment), standard chemical fertilizer, and biochar-amended plots at three different application rates (2, 4, and 6 tons per hectare), with each treatment replicated four times, totaling 60 experimental plots. Data collection involves soil sampling at baseline and post-treatment intervals, with chemical analyses conducted utilizing Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) for nutrient concentrations, pH measured via potentiometry, microbial activity assessed through enzyme assays such as phosphatase and dehydrogenase activity, and soil organic carbon determined by dry combustion using a LECO analyzer. Plant growth parameters—including seedling height, plant biomass, and chlorophyll content—are periodically measured using portable SPAD meters and destructive sampling at harvest. Crop yield data are collected at maturity, including grain weight and harvest index. Additionally, nutrient uptake is analyzed through seed and straw tissue analysis employing Atomic Absorption Spectroscopy (AAS). Data analysis involves the application of Analysis of Variance (ANOVA) to discern statistically significant differences between treatments, complemented by regression analysis to elucidate relationships between biochar dosage and crop responses, while soil and microbial data are subjected to multivariate techniques such as Principal Component Analysis (PCA). To underpin the theoretical framework, the study adopts the Soil Fertility and Resilience Theory and the Carbon Sequestration Theory, providing insights into soil functional improvements and climate change mitigation potential. It is anticipated that findings will demonstrate that biochar-amended soils exhibit significant increases in soil organic carbon, nutrient availability, microbial activity, and pH stabilization relative to controls and conventional fertilizer plots. These enhancements are expected to translate into measurable improvements in maize growth parameters, biomass, and grain yield, with optimum effects observed at 4 tons per hectare biochar application rate. The study's contribution to knowledge lies in the systematic formulation and comprehensive evaluation of biochar-based amendments tailored to local conditions, enriching the scientific understanding of biochar’s agronomic benefits and environmental sustainability. The main conclusion posits that biochar integration represents a viable strategy to improve soil health and crop productivity, especially in degraded soils. Recommendations include scaling up biochar application in smallholder farming systems, optimizing production and application protocols, and further research into long-term impacts, economic analysis, and extension strategies for widespread adoption. This study provides a scientifically validated, context-specific framework for adopting biochar as a sustainable soil management practice, with implications for improving food security and climate resilience in agricultural ecosystems.