THE EFFECTS OF ORGANIC FERTILIZERS AS A FRACTION SUBSTITUTE TO CHEMICAL FERTILIZERS ON RICE YIELD AND QUALITY, GREENHOUSE GAS EMISSIONS, AND MICROBIAL DIVERSITY IN SOIL

With the implementation of China's zero-growth policy for chemical fertilizer application, increasing attention has been directed toward exploring organic fertilizers as partial substitutes for chemical fertilizers. This study investigated rice cultivation under four fertilization regimes: conventional chemical fertilization (CK) and organic fertilizer substitution at 10% (T1), 20% (T2), and 30% (T3) of total chemical fertilizer equivalents. Key findings include: (1) Comparised with CK, the T1, T2, and T3 treatments increased rice yields by 6.22%, 9.06%, and 4.68%, respectively. Organic fertilizer substitution significantly improved grain quality through reduced chalkiness (8.78%-19.49%), decreased amylose content (9.56%12.95%), and increased protein levels (10.06%-17.29%), collectively enhancing palatability. (2) Seasonal greenhouse gas (GHG) emission patterns showed treatment-independent consistency, but cumulative emissions varied with substitution ratios. Notably, T2 and T3 achieved 10.84% and 25.92% reductions in GHG intensity (GHGI) respectively compared to CK, Dominant phyla across treatments included Proteobacteria (8.85%-10.51%), Acidobacteria (10.16%-33.82%), Bacteroidetes (10.82%-71.38%), Chloroflexi (17.05%-22.70%), and Patescibacteria (212.15%-308.41%), The precise mechanisms underlying these microbial-mediated emission processes require further investigation. These findings demonstrate that 20% organic substitution (T2) optimally balances yield enhancement (9.06%) with environmental sustainability (11.00%), providing an effective strategy for green agricultural development in rice production systems.