河西走廊绿洲灌区循环模式"农田-食用菌"生产系统氮素流动特征

河西走廊绿洲灌区在农业产业化进程加快的同时,也带来了水资源和生态环境的压力.本文利用养分流动和模型分析的方法,分析河西走廊绿洲灌区典型“农田-食用菌”生产系统(农田-食用菌集约生产模式、农田-食用菌单户生产模式、农田单作)的氮元素流动特征.结果表明:农田作物秸秆通过食用菌体系还田使氮素利用率提高了10％左右,秸秆还田氮输入量(165.6kg· hm-2·a-1)占农田氮素总输入量的37.1％,使化肥氮输入量减少,因此秸秆氮的合理循环利用可作为减少化肥投入的有效途径.但农田氮素仍有盈余,单位面积氮盈余量高达217.0 kg·hm-2· a-1,未能实现循环模式内养分平衡的理想效果,因此优化氮素管理、确定合理的大田作物和食用菌面积、调整农业产业结构是解决该问题的关键.

Nitrogen flows in"crop -edible mushroom"production systems in Hexi Corridor Oasis Irrigation Area

With the rapid development of agricultural industrialization process, has resulted in greatly negative effects on the water resources and ecological environment in the Hexi corridor oasis irrigation area. In this study, three types of "crop-edible mushroom" production systems in the Oasis Irrigation Area of Hexi Corridor were selected.The first type was an "crop-edible mushroom intensive production mode", which included edible mushroom and crop production consisting of 100 hm^-2 farmland holders; the second type was so called "crop-edible mushroom single peasant production mode; the third one was a "single cropping region which had no edible mushroom production. The characteristics of nitrogen (N) flows in these three systems were analyzed using the nutrient flows method.The results showed that it is increased by 10% of nitrogen use efficiencies through the "crop-edible mushroom" systems for crop straw returning to field.The N application rate of chemical fertilizers was 165.6 kg·hm^-2·a^-1, which accounted for 37.1% of total N input.Consequently, this confirmed that the recycling of straw N is an efficient way to reduce the application rate of chemical N fertilizer.Positive cropland N balances resulted across all three types of "crop-edible mushroom"systems, the cropland nitrogen surplus reached 217.0 kg·hm^-2·a^-1, indicating that the purpose of nutrient balance in circulation mode was not achieved as planned. It is concluded that a proper area of crop and edible mushroom with the optimization of N management and adjustment of the agricultural industrial structure are the keys to solve this issue.