Interactive effects of reduced irrigation and nitrogen fertilization on resource use efficiency, forage nutritive quality, yield, and economic benefits of spring wheat in the arid region of Northwest China

Abstract

In arid regions, supplemental irrigation and fertilization are the major driving factors for sustaining crop pro-duction. With the increasing water scarcity, rising fertilizer costs, and growing environmental concerns, iden-tifying appropriate irrigation and nitrogen (N) amounts for simultaneously improving resource use efficiency and yield benefits is essential for sustainable crop production in arid regions. A two-year field study was conducted in the arid region of Northwest China to evaluate the effects of reduced irrigation and N treatments, including W80F75 (600 mm irrigation and 225 kg N ha- 1), W80F50 (600 mm irrigation and 150 kg N ha -1), W60F75 (450 mm irrigation and 225 kg N ha -1), and W60F50 (450 mm irrigation and 150 kg N ha -1) on resource use efficiency, forage yield (DM), forage nutritive values, grain yield, and economic benefit of spring wheat in comparison with the farmers' management practice (W100F100, 750 mm irrigation and 300 kg N ha -1). Results indicated that moderately reduced irrigation and N (W80F75) significantly improved the forage nutritive quality, evident by high crude protein yield, relative feed value, digestible dry matter, dry matter intake, total digestible nutrients, and net energy for lactation. No significant difference in DM yield was observed between W100F100 and W80F75 treatments during both years. However, the grain yield for W80F75 treatment was 12.9 % greater than that of W100F100 in 2015. In addition, W80F75 treatment increased the resource use efficiency, net returns, and cost-befit ratios by reducing the input amounts while maintaining comparable yields to that of W100F100. However, the W80F50, W60F75, and W60F50 treatments significantly decreased the DM, grain yield, nutritive values, resource efficiency and economic benefits of spring wheat compared to W80F75. Therefore, the application of 600 mm irrigation and 225 kg N ha- 1 to spring wheat is an appropriate management practice for reducing inputs while achieving high resource use efficiency, forage quality and economic benefits without compromising the yield of spring wheat in the arid region of Northwest China.