Rotary Tillage and Straw Mulching Enhance Dry Matter Production, Yield, and Water productivity in a Rain-fed Wheat-Soybean Double Cropping System

Aims Water deficiency and low water use efficiency severely constrain wheat yield in dryland regions. This study aimed to identify suitable tillage and straw management practices to improve water use efficiency, grain yield and water use efficiency of wheat in the dryland winter wheat-summer bean double cropping system. Methods A long-term field experiment (onset in October 2009) of four treatments—plowing with no straw mulching (PTNS), plowing with straw mulching (PTSM), rotary tillage with no straw mulching (RTNS), and rotary tillage with straw mulching (RTSM), was conducted at a typical dryland in China. The wheat yield and yield component, dry matter accumulation and translocation characteristics, and water use efficiency were investigated from 2014 to 2018. Results straw mulching significantly increased spike number, grains per spike, 1000-grain weight, and harvest index, and ultimately resulting in grain yield increases of 10.5% under PT and 20.5% under RT. Tillage and straw management significantly affected dry matter accumulation and translocation characteristics except for that straw management had no significant effect on pre-anthesis dry matter translocation. Straw mulching respectively increased water consumption by 7.4% and 10.4%, and water use efficiency by 3.1% and 9.6%, compared to treatments under PT and RT without straw mulching. Straw mulching also enhanced pre-sowing water storage capacity, water-saving efficiency, and water use efficiency per unit of dry matter and grain yield. Conclusions TOPSIS confirmed RTSM's superiority through straw-induced improvements water and nutrient productivity. Rotary tillage with mulching optimizes dry matter/water yield, recommended for dryland wheat systems.