Abstract:

To select the optimal period for applying straw composting agents when returning corn straw to the field in soils of different textures, experiments on returning corn straw to the field were conducted in medium loam and sandy loam soils in the irrigation area of the West Liaohe Plain from 2021 to 2022, and three treatments were set up: composting agent + straw returning in spring; composting agent + straw returning in autumn; and straw returning alone (CK). The effects of combined application of straw composting agent at different periods on corn yield, soil fertility and enzyme activity were studied. The results showed that in 2021, compared with CK, there were no significant differences in corn yield and its constituent factors among the treatments, but they affected soil enzyme activities. In medium loam soil, applying composting agent in combination in autumn could increase the activities of soil sucrase, alkaline phosphatase and cellulase, while in sandy loam soil, it could increase the activities of soil urease, alkaline phosphatase and cellulase. In 2022, compared with CK, the application of composting agents in both medium loam soil in spring and sandy loam soil in autumn increased the thousand-grain weight and the number of effective ears, thereby increasing the corn yield. In medium loam soil, applying composting agent in spring could increase the activity of soil cellulase, while in sandy loam soil, applying composting agent in autumn could increase the activities of soil sucrase and cellulase. The application of composting agent in medium loam soil in autumn increased the alkali-hydrolyzable nitrogen content in 0-15, 15-30 and 30-45 cm soils by 24.11%, 27.79% and 23.08% respectively, while the increase in the contents of available potassium and available phosphorus in soil was relatively large when composting agents were applied in spring. The combined application of composting agents in sandy loam soil in both spring and autumn increased the content of available nutrients in the soil, among which the combined application in autumn had a greater increase. The application of composting agents in medium loam and sandy loam both increased the soil organic matter content by 0-15 cm and 15-30 cm respectively. The increase was greater when composting agents were applied in autumn in medium loam, while the opposite was true in sandy loam. The application of composting agents when returning straw to the field in spring in medium loam soil could effectively increase soil nutrient content and enhance corn yield. In sandy loam soil, the effect of returning straw to the field in autumn combined with the application of composting agents is better.

Key words: corn, returning straw to the field, straw composting agent, soil enzyme activity, soil nutrient content