Assessment of Biochar's Effectiveness in Enhancing Soil Fertility and Carbon Sequestration

Thesis Abstract

This study investigates the effectiveness of biochar application in enhancing soil fertility and promoting carbon sequestration within agricultural systems, responding to the urgent need for sustainable soil management practices amidst increasing climate change concerns. Despite growing interest in biochar as a soil amendment, limited empirical evidence exists regarding its long-term impacts on soil health and carbon dynamics under diverse environmental conditions. The primary aim of this research is to assess the influence of different biochar types and application rates on soil nutrient status and carbon stock enhancement, with specific objectives to measure changes in soil organic carbon, nutrient availability (nitrogen, phosphorus, potassium), and soil pH, and to evaluate the relationships between biochar properties and soil improvement metrics. The research adopts a quantitative field experiment design, employing a randomized complete block design with three replicates for each treatment. The population involved is a collection of 180 plots located in a maize-growing region of the central valley, spanning an area of approximately 15 hectares. The sample comprises 60 plots subjected to five biochar treatments (0, 5, 10, 15, and 20 tonnes per hectare), prepared from locally sourced agricultural residues through pyrolysis at 500°C, characterized via proximate and ultimate analyses to determine elemental composition, surface area, and porosity. Data collection involved soil sampling pre-application and at three, six, and twelve months post-application, analyzed through standard laboratory procedures such as Walkley-Black for organic carbon, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for nutrient concentrations, and pH meters for soil acidity. Additional data on crop yield and biomass were gathered to contextualize soil findings. Data analysis employs statistical techniques including descriptive statistics, analysis of variance (ANOVA) to compare treatment effects over time, and multiple regression analysis to examine relationships between biochar properties and soil health indicators. Also, a repeated measures approach assesses temporal trends in soil parameters. The study synthesizes findings within the framework of the Soil Carbon Sequestration Theory and the Resource-Dimensional Model of Soil Fertility, emphasizing the mechanisms by which biochar influences microbial activity, nutrient retention, and carbon stabilization. Anticipated results suggest that biochar application significantly increases soil organic carbon content and nutrient retention, with higher application rates yielding more pronounced effects. Specific biochar properties, such as high surface area and ash content, are expected to correlate with improved soil fertility indicators. The study anticipates revealing a positive linear relationship between biochar dosage and soil health parameters, along with sustained improvements over the 12-month period. These findings are poised to fill an existing gap in empirical data on the long-term impacts of biochar in similar agro-ecological zones, and contribute to broader understanding of biochar as a climate-smart practice capable of sequestering atmospheric carbon while boosting soil productivity. The research's main conclusion underscores biochar's potential as a practical and sustainable soil amendment, capable of simultaneously addressing soil degradation and carbon mitigation challenges. It is recommended that policymakers integrate biochar application into existing land management strategies, with further research needed to optimize biochar properties and application practices for different crop systems and environmental conditions. The study advances scientific knowledge by providing comprehensive, field-based evidence of biochar's multifaceted benefits and underlying mechanisms, thereby informing sustainable agriculture and climate change mitigation policies at regional and national levels.