关键词: 旱地, 小麦, 氮、磷肥, 产量, 籽粒蛋白质, 表观氮磷平衡, 土壤养分累积

Abstract:

【Objective】This study aimed to explore the relationship of nitrogen (N) and phosphorus (P) fertilizer rates to wheat grain yield and protein content, the N and P removal and their balance in soil in a long-term and location fixed field experiment, for scientifically reducing fertilizer inputs, and wheat grain yield increase and nutritional quality improvement. 【Method】A long-term and location-fixed field experiment was initiated in 2004 in the Loess Plateau, and samples were collected during the cropping years of 2022-2024, to investigate effects of N and P fertilization on wheat yield, yield components, grain protein content, grain P and potassium (K) content, soil nutrient total accumulation, and apparent N and P balances. 【Result】Wheat yield and grain protein content were found quadratically correlated with the N rate, and the highest yield of 6 905 kg·hm^-2 and highest protein content of 145.4 g·kg^-1 were attained at 196 kg·hm^-2 and 276 kg·hm^-2 of N, respectively. When the fertilizer N input was equal to the wheat N removal at the N rate of 162 kg·hm^-2, wheat yield and protein content were 6 853 kg·hm^-2 and 135.9 g·kg^-1, respectively, which were 0.8% and 3.4% lower than those when the yield was maximized, and 3.7% and 6.6% lower than those when the grain protein was maximized, but the N rate was reduced by 17.3% and 41.4%, and soil nitrate N total accumulation was reduced by 21.7% and 51.6%, respectively. As the grain production target was set to realize the medium-strong grain gluten protein of 130 g·kg^-1, the N rate could be reduced by 19.2% to 131 kg·hm^-2 with the yield as high as 6 713 kg·hm^-2 and the soil nitrate N total accumulation reduced by 22.7%, compared with that when the fertilizer N input was equal to the wheat N removal. Wheat yield and grain protein content were quadratically correlated with the P rate, and the highest yield of 6 565 kg·hm^-2 and the lowest protein content of 121.8 g·kg^-1 were attained at 55.3 and 87.3 kg·hm^-2 of P rate, respectively. When the fertilizer P input was equal to the wheat P removal at the P rate of 11.4 kg·hm^-2, wheat yield and protein content were 4 678 kg·hm^-2 and 142.6 g·kg^-1, respectively, and the P rate was reduced by 79.5%, protein content was increased by 11.0%, but yield was reduced by 28.7%, and soil N total accumulation was increased by 82.3%, compared with that when the yield was maximized. With the grain production target was set to realize the medium-strong gluten grain protein of 130 g·kg^-1, the P rate could be increased by 329.5% to 48.8 kg·hm^-2 and the yield could be increased by 39.4% to 6 523 kg·hm^-2, and also nitrate N total accumulation was reduced by 41.1% in soil, compared with that when the fertilizer P input was equal to the wheat P removal. 【Conclusion】For balancing wheat yield and grain protein increase as well as soil nutrient balance in calcareous soils at the northwestern dryland area, the wheat production should aim at high yields and medium-strong grain gluten protein, and N application rates should be 0.64-0.88 times of the aboveground N accumulation, as well as the P application rates should be 2.02-2.22 times of the aboveground P accumulation under the growing system when the crop straw was returned.

Key words: dryland, wheat, nitrogen and phosphorus fertilizer, grain yield, grain protein, apparent nitrogen and phosphorus balance, soil nutrient accumulation