Increasing maize production and preventing water deficits in semi-arid areas: A study matching fertilization with regional precipitation under mulch planting

Maize production in semi-arid areas is increasingly at risk due to limited and uneven precipitation, and is further constrained by unvalidated nutrition management practices. Matching fertilization levels to regional precipitation, however, can ensure sustainable water use and crop productivity. From 2014-2017, a 4-year field experiment was performed to evaluate the effects of fertilization at five levels (N 0+P2O5 0 kg ha(-1), N 117+ P2O5 59 kg ha(-1), N 173+ P2O5 87 kg ha(-1), N 229+ P2O5115 kg ha(-1), and N 285+ P(2)O(5)143 kg ha(-1)) under two typical ridge-furrow mulch plantings (full plastic film mulching, RFF; half plastic film mulching, RFH) on soil water storage, maize yield performance, and water use efficiency (WUE) in a rainfed semi-arid region of the Loess Plateau, China (430 mm and 8 degrees C in average annual precipitation and air temperature respectively). Fertilization promoted evapotranspiration (ET) and increased maize grain yields by 97.9-141.8 % and WUE by 94.4-122.5 % under both mulch plantings. However, soil water storage at sowing (SWSs) was reduced from 575.5 mm in 2014 to 358.8-500.0 mm under RFF and to 327.4-460.3 mm under RFH in 2017, with the water imbalance exacerbated by the increase in fertilization level. This study reveals that coordinating fertilization with SWSs to optimize ET can promote sustainable water use and maize yields, and thus fertilization at N 180.9+P2O5 90.5 kg ha(-1) is recommended under RFF, while that at N 120.1+P2O5 60.5 kg ha(-1) under RFH in the semi-arid rain-fed agricultural areas. Although RFF can maintain sustainable water use at higher fertilization level and achieve higher grain yields and WUE compared with RFH, RFH performances a water-saving potential of 60 mm compared with RFF, as evidence shows that the available water (SWSs plus precipitation) to ensure sustainable use of water requires 370-760 mm under RFH, but 440-825 mm under RFF according to a dynamic warning system to avoid water deficit.