Unbalanced fertilization was the key reason for NO3-N accumulation, reasonably fertilization, organic manure and NPK could reduce the NO3-N residual.

• 不平衡施肥是引起土壤NO3-N大量累积的重要原因,施用有机肥以及NPK合理配合施用可明显地减少土壤NO3-N的残留。