Plastic film mulching increases yield, water productivity, and net income of rain-fed winter wheat compared with no mulching in semiarid Northwest China

Whole-ground plastic film mulching with thin soil mulching above the film (PMS) and no mulching (NM) are the two dominant planting patterns for winter wheat in the semiarid rain-fed region (mean annual precipitation <450 mm) of Northwest China. In this study, differences in water consumption and production performance between PMS and NM were analyzed, as well as reasons for differences in wheat yield, in 24 field experiments conducted from 2008 to 2019 at three sites. Compared with NM, PMS had higher average grain yield (23.2%), crop water productivity based on grain yield (25.6%), and net income (603 ¥ ha−1) across all 24 experiments. In PMS, yield stability also improved under different environments. Yield differences between planting patterns and among environments primarily depended on differences in spike number ha−1. Average consumption of pre-sowing stored water in soil from 0 to 200 cm in PMS and NM accounted for 38% and 35%, respectively, of total evapotranspiration (ET). In early (sowing–jointing), middle (jointing–flowering), and late (flowering–maturity) phases, average water consumption in PMS was 36.4%, 39.3%, and 24.3%, respectively. In the middle phase, PMS increased water consumption by 29 mm and the proportion of water consumption relative to total ET by 5.6% compared with NM. In early and late phases, water consumption was similar in PMS and NM. Increased water consumption in the middle phase could increase vegetative growth and sink capacity (grain yield ha−1). ET, yield, and vegetative growth were highly positively correlated with one another. Compared with NM, PMS significantly increased yield and crop water productivity by maximizing transpiration, increasing water consumption in the middle phase, and improving use of pre-sowing stored water. In conclusion, PMS is suitable to cultivate wheat for improving water productivity and economic benefits in the semiarid rain-fed agricultural region of Northwest China.