Irrigation, Straw, and Nitrogen Management Benefits Wheat Yield and Soil Properties in a Dryland Agro‐Ecosystem

Soil water, organic C, and N management practices exert strong influences on winter wheat ( Triticum aestivum L.) yield and soil properties under dryland farming conditions. Here, a 9‐yr field experiment was conducted in northwestern China using treatments that included nine factorial combinations of three cultivation practices, conventional cultivation (CC), straw mulching (SM), and supplementary irrigation (SI), and three N application rates (0, 120, and 240 kg N ha −1 ). Relative yield gradually declined under CC and SM with N, yet remained steady under SI. Without N, yield decreased by 50 to 60%. Soil organic carbon (SOC), labile organic carbon (LOC), total nitrogen (TN), and available potassium (AK) in the 0 to 20 cm (upper) soil layer were significantly increased by SM but were unaffected by SI treatments. After wheat harvest, N application increased SOC, LOC, and TN in the upper soil layer by an average of 4.81, 20.70, and 7.61%, respectively, and decreased AK by 6.12%. The cultivation practice and N fertilizer effects on soil properties were more pronounced in upper than deeper layer (20–40 cm). At soil depths of 0 to 100 cm, nitrate accumulation under N 240 exceeded 69.27% of the critical environmental risk value. Thus, SI + N 120 achieved a high and stable wheat yield, and SM + N 120 increased soil fertility. However, the two combinations applied over 9 yr did not meet both high soil fertility and high productivity needs. Additionally, cultivation practices with high N fertilizer are not sustainable soil management techniques in dryland regions.