QUANTIFYING THE CONTRIBUTION OF ORGANIC AMENDMENTS TO LONG-TERM SOIL CARBON SEQUESTRATION AND FERTILITY

Abstract

This study evaluated the effects of various organic amendments—including compost, manure, biochar, and chitin—on soil health, microbial activity, and crop performance under field conditions. A mixed-methods approach combining quantitative soil analysis and plant growth measurements with qualitative stakeholder input was employed. Results showed that organic amendments significantly improved soil pH, microbial biomass carbon, nitrogen mineralization, and enzymatic activities. Among all treatments, chitin-based amendments consistently outperformed others, resulting in the highest increases in microbial biomass (300 mg/kg), nitrogen mineralization (5.2 mg/kg/day), and plant biomass yield. Enhanced nutrient uptake and enzymatic activity were also observed, particularly in urease and dehydrogenase assays. The application of microbial inoculants alongside organic amendments promoted further improvements in nutrient absorption, root development, and disease resistance. Notably, disease incidence was reduced by up to 45% under chitin treatment, indicating strong biocontrol potential. Visual analyses reinforced these findings, with significant differences in soil and plant parameters across treatments. The results support the integration of organic amendments as a sustainable solution for enhancing soil fertility and crop yield while minimizing dependence on synthetic inputs. This study highlights the ecological and agronomic benefits of organic matter incorporation and advocates for biologically based soil management strategies in sustainable agriculture.