Higher yield sustainability and soil quality by manure amendment than straw returning under a single-rice cropping system

Combined application of chemical fertilizers with organic amendments has been shown to improve soil fertility and agronomic performance of rice. The responses of sustainable rice production and soil quality to long-term different fertilization regimes have not been widely discussed. What is the effect on rice yield and soil quality under different fertilization management practices? A ten-year field trial was performed to systematic evaluation the impact of different fertilization regimes [no fertilized (control), chemical fertilizers alone (NPK), NPK along with cattle manure application (NPK+m), NPK along with rice straw return (NPK+s)] on rice grain yield, yield sustainability, and soil quality. A total of twenty soil indicators in two-layer soil depth (0–15 cm and 15–30 cm) were determined, including soil physical, chemical and biological indicators. The NPK+m produced higher averaged rice grain yield, increased by 11.6% and 4.3% for rice cultivar LYP9, 10.5% and 7.6% for cultivar YY12, respectively, compared to the NPK and NPK+s treatments. In addition, sustainable yield index (SYI) was the highest for both rice cultivars in the NPK+m treatment. However, the relative rice grain yield (NPK+s/NPK) against time showed a significant (P < 0.05) downward trend for LYP9. Soil total organic carbon (SOC) and total nitrogen (TN) in the surface soil significantly increased by 10.5–17.6% when NPK applied along with cattle manure or rice straw over time. The NPK+m had significantly higher soil P, Ca, Fe, Cu, and Zn contents in both soil depths than the other fertilization practices. However, no differences in K contents were observed among fertilization treatments, which decreased by half compared with the initial value. The random forest model analysis showed that available P, K and soil acid phosphatase had greater impacts on rice grain yield than did the other parameters. Soil quality index (SQI) value calculated by the minimum data set method were the highest in the NPK+m. A significantly positive correlation between the SQI and SYI (y = 0.52x + 0.4, R2 = 0.4, P < 0.05), indicating that SQI was an important factor contribution to sustainable rice production. The NPK+m had more stable rice production and higher soil quality index than the NPK+s and NPK alone treatments. High and sustainable rice yields could be achieved by combined application of cattle manure and chemical fertilizers.