Availability of fertilizer recommendation for winter wheat based on Nutrient Expert System in Yangtze River Valley

Objectives In the Yangtze River Valley, winter wheat field experiments were conducted with the NPK application rate recommended by the Nutrient Expert for Winter Wheat (NE), which was based on yield response and agronomic efficiency for wheat in the Yangtze River Valley, to evaluate the effect of the NE on winter wheat in the Yangtze River Valley.

Methods In 2019, 50 on-farm experiments were conducted in Sichuan, Yunnan, Anhui, Hubei, Jiangsu and Zhejiang, China. Each experiment included five treatments: nitrogen, phosphorous and potassium fertilizer input calculated using Nutrient Expert for Winter Wheat (NE), farmers' practices (FP), and N omission, P omission or K omission treatments based on the NE treatment. The difference between NE and FP was compared in terms of yield, economic benefit, fertilizer use efficiency, nitrogen loss and greenhouse gas emissions.

Results Compared with FP treatment, NE treatment significantly reduced the application rates of N, P and K fertilizers (P < 0.001), with decrement by 57, 10 and 8 kg/hm², or by about 26.6%, 13.3% and 12.9%. The wheat yield was significantly increased by 365 kg/hm² or by 7.9% in average (P < 0.001). The fertilizer cost was significantly reduced by an average of 429 yuan/hm², or by 20.9% (P < 0.001). The economic benefit was significantly increased by an average of 1446 yuan/hm², or by 17.7%, in which 55.5% of all the increased economic benefit was from the increase in yield (P < 0.001). NE treatment significantly improved the fertilizer use efficiency of winter wheat in the Yangtze River Valley (P < 0.001). Compared with FP treatment, the agronomic efficiency (AE) of N, P and K were increased by 6.5, 8.3 and 8.6 kg/kg, or by 67.7%, 143.1% and 159.3%. The partial factor productivity (PFP) were increased by 10.9, 17.9 and 24.8 kg/kg, or by 49.1%, 28.8% and 34.4%. The recovery efficiency (RE) of N, P and K were increased by 15.3, 11.9 and 27.2 percentage points, or by 52.9%, 132.2% and 87.7%, respectively. NE treatment significantly increased N uptake in aboveground part (P < 0.001) and significantly decreased N loss (P < 0.001). N uptake of aboveground part in NE treatment was 3.0 kg/hm² higher than that of FP on average, with an increase of 2.5%; by contrast, the reactive N losses intensity of NE was N 4.0 kg/t (37.7%) less than that of FP on average; NE had a decrease of an average of 0.7 kg/hm² in the total N₂O emission compared to FP, with a decrease of 28.0%; the greenhouse gas emissions intensity of NE showed an average decrease of CO₂ eq 308.4 kg/t (36.5%), compared with that of FP.

Conclusions The results of winter wheat field experiments in the Yangtze River Valley have proved the availability of the Nutrient Expert for Winter Wheat (NE). Using the method, the N, P, K fertilizer rates could be reduced by 26.6%, 13.3% and 12.9%, while the yield, economic benefit and fertilizer use efficiencies be improved significantly, and the N loss and greenhouse gas emission are effectively reduced. So the NE method is available with or without soil test results and is suitable for the winter wheat in the Yangtze River Valley of China.