种植玉米与休闲对土壤水分和矿质态氮的影响

【目的】研究不同种植模式下，农田土壤水分和矿质态氮的动态及其相互关系，对优化作物种植方式和养分资源管理，调控农田土壤硝态氮淋溶有重要意义。【方法】在黄土高原南部有大量氮素残留背景的田块上，研究了夏季多雨季节，种植作物与休闲对土壤水分与矿质氮的影响。【结果】在降水（含灌水82 mm）364 mm的夏季，休闲可使0～200 cm土层的贮水量达到600 mm，比播种前高204 mm，比种植作物高39 mm。种植作物的土壤水分可下渗至180 cm深的土层，休闲土壤中则可下渗到260 cm深处。种植作物时0～200 cm土层的硝态氮残留量为78 kg·ha-1，比休闲时减少89 kg·ha-1，且硝态氮主要分布在60 cm以上的土层。休闲时硝态氮却被淋到了220 cm深的土层。【结论】硝态氮向下层土壤的移动显著滞后于水分，夏季种植玉米可有效防止硝态氮向下层土壤的淋移。

Influence of Planting Maize and Fallowing on Soil Moisture and Mineral Nitrogen

【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.