Abstract

Soil carbon sequestration through amendments offers a promising strategy for climate change mitigation while enhancing soil fertility. This study compared the efficacy of biochar and basalt rock dust amendments on soil organic carbon (SOC) dynamics in wheat-maize rotation systems. A two-year field experiment was conducted with four treatments: control (T1), biochar at 10 t ha⁻¹ (T2), basalt at 20 t ha⁻¹ (T3), and combined application (T4). Results showed that biochar application increased SOC by 42.3% compared to control, while basalt increased it by 28.6%. The combined treatment showed the highest SOC increase (56.8%) with significant improvements in soil aggregation and microbial biomass carbon. Biochar demonstrated superior carbon stability with a mean residence time of 85 years compared to 45 years for basalt-derived carbon. However, basalt showed greater enhancement of mineral-associated organic matter formation. Both amendments significantly increased crop yields, with the combined treatment showing 34% and 41% yield increases in wheat and maize, respectively. Economic analysis revealed positive net returns for all amendment treatments despite high initial costs. This study demonstrates that integrating biochar and basalt amendments could maximize soil carbon sequestration potential while ensuring agricultural productivity in intensive cropping systems.