Straw mulching for enhanced water use efficiency and economic returns from soybean fields in the Loess Plateau China

Water shortages threaten agricultural sustainability in the semi-arid areas of the Loess Plateau. Judicious mulching management can improve water conservation practices to alleviate this issue while increasing crop productivity. We investigated the effect of straw strip mulching and film mulching on soil water consumption, temperature, growth, grain yield, and economic income of soybean [Glycine max(Linn.) Merr.] from 2017 to 2018 in Qingyang on the semi-arid Loess Plateau in China using four treatments: (a) alternating ridges and furrows with ridges mulched with white polyethylene film (PMP), (b) alternating flat and bare land with only the plat mulched by white polyethylene film (PMF), (c) alternating strips mulched with maize (Zea mays L.) straw (SM), and (d) traditional land planting without mulching (CK). The mulching treatments (PMP, PMF, and SM) increased soil water consumption and soil water use efficiency. The SM, PMF, and PMP treatments had 12.3–12.5, 16.8–22.1, and 23.2–24.2 mm higher soil water consumption (0–120 cm depth) than CK, most of which occurred in the 60–120 cm soil layer. Compared with CK, PMP and PMF significantly increased soil temperature by 1.30–1.31 °C and 0.76–1.00 °C, soybean grain yield by 38.6–39.0 % and 38.8–44.2 %, and water use efficiency (WUE) by 27.7–32.8 % and 30.8–37.5 %, respectively, while SM significantly decreased soil temperature by 0.96–1.15 °C, and increased grain yield by 21.8–25.4 % and WUE by 16.9–21.9 %. PMP and PMF did not significantly change soil water consumption, WUE, or grain yield. The SM treatment increased net income by 501.3–691.7 and 1914.5–2244.9 CNY ha⁻¹ relative to PMP and CK, respectively, but PMF and SM did not significantly differ. Therefore, the SM system could help increase grain yields and economic returns in dryland soybean production, avoiding the adverse effects of the increasingly popular plastic mulching approach.