Design and evaluate sustainable biochar soil amendment for crop productivity

Thesis Abstract

Soil degradation and declining crop yields pose significant challenges to sustainable agriculture, emphasizing the urgent need for environmentally friendly soil amendments that enhance productivity while preserving soil health. This study aims to design and evaluate a sustainable biochar-based soil amendment to improve crop yield and soil quality, addressing the dual objectives of maximizing agronomic performance and ensuring environmental sustainability. The specific objectives include (1) to produce biochar from locally available biomass through optimized pyrolysis conditions, (2) to assess the physicochemical properties of the biochar produced, (3) to formulate different biochar soil amendment treatments and evaluate their effects on crop growth, and (4) to analyze the economic and environmental sustainability of the application. The research adopts a mixed-methods experimental design, combining laboratory, greenhouse, and field trials. The study population comprises maize and soybean crops cultivated on plots within the Central Plains Agricultural Zone, with a total sample size of 120 experimental units arranged in a randomized complete block design. Biochar samples are produced from agricultural residues such as maize stalks and rice husks, pretreated and pyrolyzed at temperatures ranging between 450°C and 550°C. The biochar’s physicochemical properties, including pH, cation exchange capacity, porosity, surface area, and nutrient content, are rigorously analyzed using techniques such as Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface area analysis, and elemental analysis. Field applications involve applying biochar treatments at different rates (2, 4, and 6 tons per hectare) in combination with organic compost, with control plots receiving standard fertilization practices. Data collection employs quantitative methods, measuring crop growth parameters (e.g., plant height, biomass, grain yield), soil properties pre- and post-treatment, and nutrient uptake using standard agronomic procedures. Additionally, economic analysis employs cost-benefit analysis, while environmental assessment uses life cycle assessment (LCA) frameworks to evaluate the sustainability profile of the biochar amendments. Statistical analysis involves analysis of variance (ANOVA) to determine the effects of biochar treatments on crop yield and soil properties, with regression analysis used to model relationships between biochar characteristics and crop performance. The physicochemical data inform multivariate analysis to identify the most influential properties contributing to crop productivity. The study also applies the Theory of Planned Behavior to explore farmers' willingness to adopt biochar technology, through thematic analysis of qualitative interview data from 30 local farmers. Expected findings suggest that biochar produced under optimized pyrolysis conditions exhibits high surface area, stable organic carbon, and nutrient retention capabilities, leading to significant improvements in soil pH, cation exchange capacity, and organic matter content. Field trials are anticipated to demonstrate that biochar amendments at 4 tons per hectare can increase maize and soybean yields by 20–30% compared to conventional practices, with enhanced soil resilience and reduced fertilizer requirements. The economic analysis is expected to show favorable cost-benefit ratios, especially when factoring in improved yields and reduced inputs, while the LCA highlights potential environmental benefits through carbon sequestration and reduced greenhouse gas emissions. This study contributes to the existing body of knowledge by providing a comprehensive framework for the sustainable production and application of biochar tailored to local agricultural contexts, integrating physicochemical characterization with agronomic and socio-economic evaluations. The findings will inform policymakers, farmers, and agronomists on best practices for biochar implementation, emphasizing both environmental sustainability and crop productivity enhancement. The main conclusion reinforces that biochar, when designed and applied appropriately, offers a viable, sustainable strategy for improving soil fertility and crop yields in degraded soils. Recommendations include promoting local biomass-based biochar production, developing farmer education programs on biochar benefits, and fostering policies incentivizing sustainable soil management practices. Future research should explore long-term field effects, optimal application rates across diverse crops, and the socio-economic barriers to widespread adoption.