Determining optimal nitrogen management to improve rice yield, quality and nitrogen use efficiency based on multi-index decision analysis method.

Background: Reasonable nitrogen (N) supply is critical for increasing rice yield while improving grain quality and nitrogen use efficiency (NUE). However, the trade-off relationship between yield, quality and NUE of rice under N management has not been well understood enough. In the present study, a 2-year field experiment was conducted to identify optimal N fertilizer management practices that resulted in high-yield, high-quality and high-NUE by using the technique for order preference by similarity to an ideal solution (TOPSIS) with entropy weight (EW) method.

Results: All the parameters of rice yield, quality and efficiency were remarkably affected by fertilization treatments. Compared with farmer's fertilization practice (FFP), optimizing N fertilizer treatment (OPT) and substituting 20% of N fertilizer with pig manure based on OPT treatment (OPTM) increased grain yield (2.87-6.62%) by maintaining higher 1000-grain weight and filled grains rate. The agronomic NUE (AE) and N partial factor productivity (PFP) under OPT and OPTM treatment were also remarkably increased by 32.81-43.01% and 28.59-33.28% with respect to the value under FFP treatment, respectively. Meanwhile, OPT and OPTM significantly improved the milling quality of rice by increasing brown rice rate (0.71-1.17%) and head rice rate (1.34-2.31%). OPT and OPTM significantly improved appearance quality by decreasing chalkiness and eating quality by reducing amylose content in 2020. The TOPSIS with EW showed that rice comprehensive evaluation could be maintained at a high level under OPT and OPTM.

Conclusion: OPT and OPTM were nutrient management modes of high-yield, high-quality and high-efficiency, and promising practice to improve rice comprehensive productivity. This strategy is also highly-consistent with the United Nations Sustainable Development Goals. © 2023 Society of Chemical Industry.