4R nitrogen management produced more yield and benefit on rice in Ningxia, China

Imbalanced use of nitrogen (N) in rice production is common in the northwestern province Ningxia, leading to possibilities of N losses to the environment. The objective of this project was to use the Nutrient Expert® (NE) tool to make site-specific fertilizer recommendations for rice, based on the 4R Nutrient Stewardship Principles, to help improve N use efficiency and farmers' income.

The present study had four treatments with three replicates: 1) no N (control); 2) farmer practice (FP) of 270-90-60 kg N-P₂O₅-K₂O/ha, with broadcasting of 60% N, all P and K before transplanting, and the rest 40% N applied in two equal splits, after translation and at tillering; 3) NE recommendation of 195-66-112 kg/ha, with broadcasting of 1/3 N and all P basally, rest of the N applied in two equal splits at tillering and at panicle differentiation, while 50% K is applied before transplanting and the rest at panicle differentiation; and 4) NE recommendation with full N (60% through controlled-release urea (CRU) and 40% through regular urea), P and K were banded at 3 to 5 cm depth and 5 cm away from the seedlings during transplanting by machine.

The results indicated that N application produced 3,400 to 3,590 kg/ha or 90 to 95% more rice grain than the control. NE recommendation with regular urea and broadcasting produced similar yield and benefit to FP, but improved the agronomic efficiency (AE) by 4.4 kg grain/kg N and saved 75 kg N/ha. NE recommendation integrated with CRU and banding resulted in 196 kg/ha of extra grain yield, US$48/ha of extra income, and improved the AE by 1 kg grain/kg N over the NE treatment where regular urea was broadcasted; and produced 59 kg/ha of extra yield, US$30/ha extra benefit, and higher AE (5.3 kg grain/kg N) than the FP treatment. Therefore, 4R N management in rice production in Ningxia could improve yield, farmers' income, and the N use efficiency.