Quantitative analysis and optimization of three film mulching methods and nitrogen application rates on maize yield and productivity

Understanding water-nitrogen interactions under mulched conditions and optimizing nitrogen application rates is crucial for ensuring maize productivity in semiarid regions. Through two-year field experiments (2021–2022), the effects of film mulching and nitrogen application on maize yield, water consumption, and water-nitrogen use efficiency were studied and optimal nitrogen application ranges were proposed. Three film mulching methods such as full-film double-ridge furrow sowing (FDS), flat film mulching (FCF), single ridge film mulching (SRC), in combination with four nitrogen application levels 0 (N0), 135 kg ha−1 (N1), 180 kg ha−1 (N2), and 225 kg ha−1 (N3) were evaluated. Results demonstrated that FDS and SRC significantly improved maize yield and productivity while comparing to FCF. Furthermore, yield, water use efficiency (WUE), and nitrogen agronomic efficiency (NAE) demonstrated positive correlations with nitrogen application rate under FDS and SRC. In contrast, the nitrogen partial factor productivity (NPFP) related negatively with elevating nitrogen inputs under three methods. Under FCF, the WUE increased with increasing nitrogen application. Furthermore, the yield and NAE showed an increasing trend from N0 to N2 levels, but decreased at N3 levels. The ETc at N3 for FDS, FCF, and SRC showed 0.30–4.49 %, 0.86–3.87 %, and 6.65–10.19 % reduction compared to other nitrogen treatments. Based on the results for yield, ETc, and NPFP, the SRC mulching method was more suitable under low nitrogen levels (N0-N2). Under high nitrogen level (N3), the FDS mulching method performed better. Regression models showed that SRC and FDS can enable yield, WUE, NPFP, and dry matter mass to reach 80–100 %, 85–100 %, 90–100 %, and 95–100 % of their respective maximum values with the nitrogen ranges of 135–225 kg ha−1, 164–225 kg ha−1, 188–225 kg ha−1, and 214–225 kg ha−1. This study provides support for optimizing cultivation practices and determining appropriate nitrogen application ranges in semi-arid lands.