Crop-Soil-Environment Benefits of Equivalent Carbon Input from Organic Amendments in Rice Production Ecosystems

Sustainable production of rice is essential in supplying staple food worldwide and mitigating climate change. However, the comprehensive evaluation of different organic amendment applications in single-season rice agroecosystem on soil organic carbon (SOC), greenhouse gas (GHG) emissions, and the carbon footprint (CF) have been inadequately recorded. We conducted a one-year field experiment, comparing chemical fertilizer (control) with straw, biochar, and manure application with equivalent carbon input (1200 kg ha⁻¹), and evaluated their soil crop environmental benefits. Our findings revealed that three organic amendments significantly increased SOC storage, leading to enhanced yields. Among them, manure incorporation resulted in the highest SOC storage and yields, increasing by 13.68% and 26.08%, respectively. However, manure incorporation also caused significant increases in global warming potential (GWP) by 44.58%, mainly due to enhanced methane emissions. Despite having lower temporary storage of C, the CF of biochar (-3.96 ± 0.22 t CO₂-eq ha⁻¹) was similar to manure incorporation due to its GHG emission mitigation. When evaluating the comprehensive benefits on crop-soil-environment by Z-score standardization method, biochar incorporation demonstrated the highest positive effects on the rice agroecosystem, followed by the manure incorporation. Straw application should be avoided due to its high C/N ratio, which limits its benefits in terms of crop growth and GHG emission mitigation. Our results indicated biochar incorporation increased SOC storage, yield, and significantly reduced GHG emissions, leading to a substantial decrease in GWP and CF. Biochar emerges as a key strategy for achieving a balance between productivity, soil quality, and environmental sustainability in single-season rice agroecosystem.