Reduced irrigation and nitrogen coupled with no-tillage and plastic mulching increase wheat yield in maize-wheat rotation in an arid region

Irrigation, nitrogen (N) fertilization, and tillage practices for spring wheat following plastic-mulched maize were studied to provide a basis for optimizing production technology to achieve high wheat yield in arid irrigated regions. No-tillage, plastic mulching, water-nitrogen interactions, and crop rotation are the important valuable strategies for improving grain yield (GY) in arid regions, but there is lack of theoretical basis on whether no-tillage in combination with plastic film mulching from the previous crop can enhance GY of following wheat. A field experiment was conducted in an arid region of northwestern China during the 2016 and 2017 growing seasons, which evaluated all combinations of two tillage practices, two levels of irrigation, and three levels of N application. Two tillage practices included no-tillage with previous plastic mulching retained (NT), and conventional tillage (CT). Two levels of irrigation included the local conventional irrigation amount, 2400 m³ ha⁻¹ (high: I2), and the local conventional irrigation amount reduced by 20%, 1920 m³ ha⁻¹ (low: I1). Three levels of N application included the local conventional N amount, 225 kg N ha⁻¹ (high: N3), the local conventional N amount reduced by 20%, 180 N kg ha⁻¹ (medium: N2), and the local conventional N amount reduced by 40%, 135 kg N ha⁻¹ (low: N1). Compared with CT, NT increased GY, biomass yield (BY), and leaf area index (LAI) during the two study years by 10.1–10.4%, 5.4–15.1%, and 22.8–28.5%, respectively. Grain yield was 2.4–4.3% greater with I1 compared to I2, but BY was not significantly different between irrigation levels. Net assimilation rate (NAR) was 5.8–6.7% greater with N2 compared to N3, but LAI were not affected by N rate. A 20% reduction in both irrigation and N application, combined with no-tillage and retention of plastic film mulching from the previous maize crop (NTI1N2), increased GY, BY, and LAI by 15.2–22.0%, 7.8–9.7%, and 17.9–26.1%, respectively, compared to high levels of irrigation and nitrogen with conventional tillage (CTI2N3). The NTI1N2 treatment significantly increased spike number (SN), kernel number per spike (KNS), and thousand-kernel weight (TKW). Path analysis confirmed that increased SN and TKW was the main reason for improved GY with the NTI1N2 treatment. Simultaneous reduction of irrigation and N application, combined with NT and retention of residual plastic film mulching from the previous maize crop, could be considered a favorable strategy for sustainable intensification of wheat production in arid regions.