Experiments on the Influence of Corn Straw Morphological Combinations on Timely No-Tillage Sowing Soil Temperature and Moisture in Cold Regions

After corn mechanical harvest in autumn in the cold region of northeast China, straw mulching leads to high soil topsoil water content and slow ground temperature rise in the spring sowing season, which may result in a no-tillage planter being unable to operate in time, delayed sowing date, poor seedling emergence quality, and low grain yield. Based on the problems of high moisture content and low temperature in soil topsoil in the spring sowing season in conservation tillage with straw mulching, an experimental study on timely sowing in the spring sowing season was carried out from the perspective of combination optimization of attribute parameters of straw mechanical treatment. Taking the four mechanical treatment attributes as experimental factors, including straw length, straw shape, mulching form (surface covering, inter-ridge covering, and inter-ridge mixed soil covering), and stubble height after corn harvest in autumn of 2019 as experimental factors, and soil topsoil moisture content and temperature during spring sowing in 2020 as evaluation indexes, a field plot experiment was carried out by four factors and three levels of orthogonal combination test method. The results showed that all the factors had significant influence on soil topsoil moisture content and soil topsoil temperature ( p < 0.05). It is helpful to reduce the moisture content of soil topsoil and increase the temperature of soil topsoil by increasing the length of corn stalk, breaking the stalk moderately, covering the stalk between ridges, and increasing the stubble height of stalk. Design-Expert software was used to optimize the parameters. The results showed that when the length of straw was 150 mm, the shape of straw was half-cut (dividing straw into two parts evenly along the axis), the mulch was between ridges, and the stubble height was 600 mm, the moisture content of soil topsoil was 22~24% and the temperature of soil topsoil was higher than 8 °C during spring sowing. After corn harvest in autumn of 2021, corn stalks were treated in that year according to the results of parameter optimization combination. The soil topsoil moisture content and temperature were measured to be 24.4% and 8.2 °C, respectively, in the spring sowing season of 2022, which proved that the optimization results in this experiment were credible. The experimental results provide a technical reference for the implementation of conservation tillage with straw surface mulching in the cold region of northeast China.