Abstract: 【Objective】It is of great importance to study the dynamics of soil water and mineral nitrogen and their relationships for optimizing cultivation methods, nutrient management and manipulation of nitrate leaching in soils. 【Method】In this paper, a field experiment was carried out to study the influence of planting summer maize (Zea mays L. var. Shandan 911) and fallowing on soil water and mineral nitrogen in a warm and rainy summer on plots with a great deal of residual N in the soil profile, in the southern area of the Loess Plateau in northwestern China. 【Result】The soil water storage was 600 mm in the 0-200 cm soil profile of fallowing plots in the summer of 364 mm precipitation (including 82 mm of irrigation). It was 204 mm more than that before seeding, and 39 mm more than that of maize-planting plots. As far as the moisture distribution in the soil profile over the whole growing season was concerned, it was found that the water from rainfall and irrigation was able to move down to the 260 cm depth under fallowing, and it only moved down to the layer at 180 cm depth under planting. When planting maize, nitrate N residue in the 0-200 cm soil was 78 kg·ha-1, being 89 kg·ha-1 less than that under fallowing. Moreover, nitrate N in soil of the maize-planting plots mainly remained in layers above 60cm depth, and that in fallowing soil was leached down to 220 cm depth. 【Conclusion】This indicated that compared to the downward movement of water in soil, the leaching of nitrate N was obviously lagged, and planting maize could effectively prevent nitrate N from leaching down to the subsoil in summer.

Key words: planting, fallowing, moisture storage, nitrate N, ammonium N