Abstract: An 8year field experiment was conducted to study the accumulation, vertical transport and leaching  of soil NH₄⁺-N, NO₃^--N and extractable organic N (EON) affected by corn stover mulching in no-tillage system. The experiment consisted of five treatments, including a ridge tillage as control (RT), no-tillage without corn stover mulching (NT0), no-tillage with 33% corn stover mulching (NT₃₃), no-tillage with 67% corn stover mulching (NT₆₇), and no-tillage with 100% corn stover mulching (NT₁₀₀). The results showed that soil extractable N mainly existed in form of NO₃^--N, followed by EON in the no-tillage system with corn stover mulching. Corn stover mulching with different quantities significantly affected the accumulation and vertical transport of soil NO₃^--N in no-tillage system. The soil NO₃^--N was leached to the 40-80 cm soil layer in the NT₃₃ and NT₆₇ treatments, and the 40-60 cm soil layer in the NT₁₀₀ treatment. Compared to RT treatment, NT₆₇ and NT₁₀₀ treatments significantly decreased the capacity of NO₃^--N and EON pools in the 0-20 cm soil layer, and increased that of NO₃^--N pool in the 40-60 cm soil layer. Our results suggest that corn stover mulching increased the vertical transport and leaching loss of soil NO₃^--N pool from cultivation layer to deep soil in no-tillage system, and had no influence on the soil EON and NH₄⁺-N.

Key words: path analysis, morphometric trait, correlation analysis, regression analysis, Miichthys miiuy