Yield performance, land and water use, economic profit of irrigated spring wheat/alfalfa intercropping in the inland arid area of northwestern China

Context: The intercropping system has shown great advantages in adverse environments due to balanced use of diverse resources and promotion of sustainable productivity. However, identifying an optimal intercropping practice is still urgently needed in resources-limited areas, i.e., some perennial legume crop and annual cereal crop intercropping in arid areas.Objective: This study tested a hypothesis that spring wheat/alfalfa strip intercropping under irrigation could improve land and irrigation water uses compared to sole spring wheat or alfalfa, and, therefore, would ensure reliable agronomic and economic benefits in the arid areas.Methods: A three years field experiment was conducted to investigate the yield performance, resource use and economic benefit of irrigated spring wheat/alfalfa strip intercropping in the inland arid area of northwestern China. The intercropping systems with different intercropping ratios were established, including four rows of alfalfa intercropped with twelve rows of spring wheat (W12A4) and with eight rows of spring wheat (W8A4), both of which were compared with sole spring wheat (SW) and sole alfalfa (SA). All these cropping systems were provided with irrigation at four levels: 450 (I450), 360 (I360), 270 (I270), and 180 mm (I180).Results: The grain yield of spring wheat first increased and then decreased with the decrease in irrigation amount, with maximum yield achieved at I360. However, dry matter yield of alfalfa decreased with decreasing irrigation amount. Land equivalent ratio (LER) of the intercropping system was 0.72-1.05, suggesting this intercropping may not effectively save farmland. The W12A4 had higher grain yield, total dry matter accumulation, LER, and irrigation water use efficiency than W8A4. Except for the establishing year, the intercropping system produced 3.37-39.82% higher net income than SW in the other two years. There were no difference in net income and output/input ratio between W12A4 and W8A4.Conclusions: Spring wheat/alfalfa strip intercropping can be used as a productive and sustainable strategy in the arid areas, which can improve irrigation water use, produce higher grain and forage yield, and increase net income. The W12A4 with 360 mm irrigation could be extensively used in the inland arid area of northwestern China. Significance: It is recommended that this spring wheat/alfalfa intercropping should be adopted in this and similar arid areas in the world to promote sustainable development of agriculture and animal husbandry in the context of increasing population, resource constraint and climate change.