Effects of mulching measures on soil moisture and N leaching potential in a spring maize planting system in the southern Loess Plateau

A field experiment was conducted in the southern gully region of the Loess Plateau to study the effects of mulching measures on spring maize yield and nitrate accumulation in dryland areas under traditional tillage conditions. The study was performed to provide a scientific basis for spring maize planting and environmental protection in this area. The four treatments were non-mulching (CK), plastic film-mulching during the growth period (PM1), plastic film-mulching during the fallow period (PM2), and straw-mulching (JM). After 13 years of continuous application, the yield of spring maize, the nitrogen uptake by plants, and the nitrate nitrogen content at the harvest stage were measured. The results revealed that soil moisture content and water storage capacity of the three soil-mulching treatments were all higher than those of the non-mulching treatment. Soil water storage at a depth of 0-300 cm in the JM, PM1 and PM2 treatments was increased by 11.8%, 10.6% and 8.8%, respectively, compared with the CK treatment. Compared with the CK treatment, the mulching treatments significantly increased the aboveground biomass and grain yield of spring maize. The yield enhancement effect of the PM1 treatment was the most significant, with a yield of 1.1 Mg ha(-1) and an increase of 26.72%. In addition to the JM treatment, the accumulation of soil nitrate at a depth of 0-300 cm in the PM1 and PM2 treatments was less than that of the CK treatment, but the largest increase in soil nitrate (80.20% in the JM treatment) was observed at a depth of 0-100 cm. The results suggest that in the rainfed agriculture in the southern Loess Plateau, mulching cultivation can effectively increase the soil moisture content and water storage capacity. PM1, and PM2 treatments could significantly reduce the content and accumulation of nitrate nitrogen in the deeper soil profile, and the three mulching measures could slow down the deep accumulation of soil nitrate nitrogen to a certain extent.