Green manure incorporation with reductions in chemical fertilizer inputs improves rice yield and soil organic matter accumulation

Purpose A 6-year (2011–2016) field experiment was performed to explore the effects of partial substitution of chemical fertilizer by green manure on rice yield, sustainability yield index, and the building-up of different fractions of soil organic carbon, soil nitrogen, and phosphorus. Materials and methods The experiment included no fertilization (NF), chemical fertilizer only (CF 100 ), and Chinese milk vetch ( Astragalus sinicus L.) incorporation with 80%, 60%, 40%, 20%, and 0% of total N, P, and K supplied from chemical fertilizer (MVCF 80 , MVCF 60 , MVCF 40 , MVCF 20 , and MVCF 0 , respectively) treatments. The soil organic carbon fractions, soil nitrogen, and phosphorus fraction contents were measured over 6 years. Results and discussion In comparison with CF 100 treatment, the MVCF 80 , MVCF 60 , and MVCF 40 treatments significantly increased rice yield between 2013 and 2016, thus improving sustainability yield index. The soil organic carbon fractions increased 15–58%, 16–61%, 14–50%, and 12–33% in the MVCF 80 , MVCF 60 , MVCF 40 , and MVCF 20 treatments, respectively, compared with the CF 100 treatment ( p