Effects of green manure crops on concentration of inorganic nitrogen in soil solution of paddy fields and rice yield were studied to explore feasibility of reducing chemical fertilizer application through incorporating green manure crops into soil.Results showed that when the total N application rates were kept the same,compared with application of chemical fertilizer,combined application of organic material (green manure crops) and chemical fertilizer can significantly reduce NH₄⁺-N and NO₃^--N concentration in soil solution.Incorporating Chinese Milk Vetch into soil can reduce the chemical N fertilizer application rate by 44%,and also diminish the environmental risk of N runoff.