Plastic-Covered Ridge-Furrow Planting Combined with Supplemental Irrigation Based on Measuring Soil Moisture Promotes Wheat Grain Yield and Irrigation Water Use Efficiency in Irrigated Fields on the Loess Plateau, China

The purpose of this study was to investigate whether combining plastic-covered ridge and furrow planting (RF) and supplemental irrigation based on measuring soil moisture (SIMSM) can increase the grain yield and water use efficiency (WUE) of wheat (Triticum aestivum L.) in irrigated fields of Loess Plateau, China. In 2016–2018, the experiment was conducted at Doukou experimental farm (34°36′ N, 108°52′ E) with two plant systems (RF and traditional planting (TF)) and three irrigation treatments (S1 and S2: SIMSM with a target relative soil water content of 85% and 100%, respectively). The results suggest that under the TF system, SIMSM decreased the grain yield and nitrogen utilization. The reason for this may be the local low precipitation. However, the combination of RF and S2 significantly increased the WUE, protein and wet gluten concentration in the grain. In addition, the grain yield of the RF plus S2 treatment was not significantly different than that of the traditional irrigation method. These results suggest that combining RF and SIMSM with a target relative soil water content of 100% is beneficial to the synergistic improvement of the wheat yield, the wheat quality, and the water and fertilizer use efficiency in irrigated fields on the Loess Plateau.