上海郊区农田氮养分平衡及其对土壤速效氮含量的影响

Nitrogen nutrient balance and its impact on soil available nitrogen content in Shanghai suburb farmlands

通过对上海郊区的43块定位农田连续3年的跟踪监测分析，比较了50种作物以及5种不同轮作农田的氮养分平衡状况及其对土壤速效氮含量的影响。结果表明：（1）不同作物农田的氮养分盈余趋势为水生蔬菜类≥水果类〉旱作蔬菜≥大田作物≥草皮；不同轮作农田氮养分盈余大小表现为：菜菜轮作〉果树单作〉菜作轮作〉草皮单作〉作物轮作；（2）不同作物及不同轮作农田收获时土壤速效氮含量随土层的加深而逐渐降低，氮养分盈余多的农田土壤的速效氮含量也高；（3）不同作物以及不同轮作农田氮养分盈余与收获时土壤表层（0～30cm）的硝态氮和铵态氮含量呈正相关。

Nitrogen nutrient balances of the farmland soils in 50 varieties of crops and 5 types of planting patterns and its impact to soil available nitrogen nutrient content were studied in 43 site - specific locations over the past three years in Shanghai suburb, The result indicated that ： （1） The nitrogen nutrient surplus tendency of different crops farmland was： the fewflower wildrice ≥ the fruit 〉 the vegetables ≥ the crops ≥ the greensward; The nitrogen nutrient surplus of different planting patterns farmland was： the rotation between vegetable and vegetable 〉 the fruit tree only 〉 the rotation between vegetable and crops 〉 the greensward only 〉 the rotation of crops and crops; （2） Content of soil available nitrogen after harvest gradually decreased with the depths of soil profile in the farmlands of different fields and different planting patterns fields, The more soil available nitrogen contents were, the more nitrogen nutrient surplus will be in different planting patterns fields; （3） Nitrogen nutrient surpluses of the farmland soil in different crops fields and different planting patterns were positive correlated with the content of available nitrogen content in the surface soil （0 - 30 cm） in harvesting. Nitrogen nutrient surplus and NH4^＋ - N content or NO3^-- N content in the surface soil （0 - 30 cm） was significantly positive related.