From June 2004 to July 2005 , the dynamics of soil inorganic N pool and N net mineralization/nitrification rates in typical meadow Calamagrostis angustifolia wetland (TMCW) and marsh meadow C. angustifolia wetland (MMCW) in Sanjiang Plain were studied by top-closed PVC lube in situ incubation method, with the affecting factors and annual N net mineralization/nitrification investigated. The results showed that the soil inorganic N in the two wetlands had evident dynamic characteristics. The NH_4~+-N and NO_3~--N contents were much higher in TMCW soil than in MMCW soil, and the soil IN net mineralization/nitrification rates in the two wetlands presented significant fluctuations. Biological immobilization, denitrification, and abundant precipitation in rainy season were the main reasons inducing the N net mineralization/nitrification rates to be negative, and temperature, precipitation, soil organic matter content, soil C/N ratio and soil pH were the main factors resulting in the significant differences of soil inorganic N pool and N net mineralization/ nitrification rates between the two wetlands. The annual N net mineralization and nitrification and the percentage of nitrified N in mineralized N were much higher in TMCW soil than in MMCW soil, suggesting that TMCW soil was superior to MMCW soil in N availability and available N-maintaining capacity.
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