Abstract:

Context and Objective: Continuous cropping and high nitrogen fertilizer usually result in low nitrogen use effi-ciency (NUE) of crop production, underscoring the urgent need for optimized agronomic strategies in aridirrigated areas. In view of the advantage of crop rotation and optimal nitrogen application for improving ni-trogen fertilizer efficiency, optimizing cropping pattern and nitrogen management simultaneously is a practical
way to enhance NUE.Methods: From 2022-2024, following a preceding crop of plastic-mulched maize, a split plot experiment wasestablished in arid land area, no-tillage rotation wheat (NTRW), conventional tillage rotation wheat (CTRW) aswell as continuous wheat (CTCW) as the main area, 225 kg ha (N1, traditional) and 180 kg ha (N2, 20%reduction) as the sub-plot.
Results and Conclusions: NUE decreased after nitrogen reduction, whereas rotation weakened the adverse effectsof reduced nitrogen, and no-tillage further strengthened this advantage. A 20% nitrogen reduction reduced NUEby 2.2%. Under CTRW, NUE increased by 3.8% relative to CTCW, with NTRW further increased by 3.7% relativeto CTRW. Compared with CTCWN1, NUE increased by 2.7%-5.3%, thereby increasing GY by 6.7%-24.4%. Ni-trogen reduction decreased the nitrogen accumulation (NA), nitrogen contribution to grains (SNTCP) but miti-gated the risk of soil nitrate nitrogen leaching. In contrast, rotation and no-tillage primarily enhanced nitrogenaccumulation during the reproductive stage and mitigated the negative impact of nitrogen reduction on thesource-sink remobilization of nitrogen, ultimately affecting nitrogen harvest index (NHD. Furthermore, partic-ularly following fertilization, deep-layer nitrate nitrogen content was significantly reduced, and the inhibitoryeffect strengthened with increasing rotation duration. The rotation system maintained a favorable nitrogensupply for crops within the 0-50 cm soil layer even with reduced nitrogen, and the combination with no-tillfurther enhanced soil nitrogen retention capacity. The decline in nitrate reductase and glutamine synthetaseactivities under 20% reduced nitrogen was offset by rotation and no-till, with the most significant effectsobserved at the flowering stage. Random forest model revealed the improvement of NUE was primarily due toincreased flag leaf nitrate reductase activity and stem nitrogen translocation rate, while reducing the risk of deepsoil nitrogen leaching. In arid land irrigation areas, no-tillage rotation of wheat with maize covered by mulch isan effective measure for utilization of nitrogen and reduce the risk of nitrogen leaching in deep soil.Signijicance: This study demonstrates no-tillage rotation serve as an effective measure to synergistically improvenitrogen utilization and mitigate leaching loss under reduced nitrogen input in arid regions.