菜地氮素循环途径及其环境效应综述

菜地生态系统氮肥投入量大，氮素循环强度高，损失途径多，损失量大。氮素除被作物吸收外，易造成土壤硝酸盐累积，引起土壤质量下降，进而通过剖面淋洗、地表径流和硝化、反硝化等途径损失，造成地下水硝酸盐污染、地表水富营养化以及大气污染．同时土壤中过量的硝酸盐累积引起蔬菜对硝酸盐过量吸收，造成蔬菜硝酸盐超标。水体和蔬菜硝酸盐超标对人体健康存在直接的负面作用。然而菜地复种指数高，在今后仍是增加农民收入的重点产业。菜地大量氮肥的施用引起的环境问题日益突出。综述了氮素循环途径及其环境效应。

Nitrogen Cycling and Its Environment Effects in Vegetable Crop-Soil System

The intensity of nitrogen cycling in vegetable crop-soil system is high and the amount of nitrogen losses is great with various losing ways because of the excessive fertilization. Except being absorbed by crop, nitrogen is easily accumulated in soil profile which will lead to the soil quality deterioration. Furthermore the accumulated nitrogen will lose form leaching, runoff, nitrification and denitrification, and then form ground and surface water contamination and air pollution. In the same time, vegetables nitrate pollution is occurred frequently because of absorbing excessive nitrate. Water nitrate contamination and vegetable nitrate pollution will directly affect body health. However vegetable growth is an important industry in the next few years. The environment pollution of vegetable planting is serious because the high multiple crop index and the excessive fertilization. In this paper, the nitrogen cycling and its environmental effects are summarized.