Abstract: An incubation experiment was conducted to study the nitrogen supply variation of red soil during the degradation of a legume,Chamaecrista rotundifolia. The soil samples were incubated at 15℃ and 25℃,4 soluble nitrogen including nitrate nitrogen (NO₃^--N),ammonium nitrogen(NH⁺₄-N),soluble total nitrogen (TSN) and soluble organic nitrogen(SON) and 3 N-hydrolytic enzymes (urease,protease and asparaginase) were determined in the different incubation period. The results showed that 4 soluble nitrogen content increased during the degradation of C. rotundifolia,the highest contents were observed after 140 d incubation. 25℃ incubation was more beneficial than 15℃to increase The soluble nitrogen content of red soil in orchard were higher when incubated at 25℃ than 15℃. The variation of TSN,SON and NO₃^--N content with time were fitted by cubic curve equation. Urease,protease and asparaginase activities of red soil were also significantly increased by the application of C. rotundifolia. The changes of protease and urease activity could be fitted by exponential equation and cubic curve equation. It concluded that the soluble nitrogen was increased by application of C. rotundifolia in red soil,therefore the measure of incorporating C. rotundifolia to red soil would increase the N supply in mountain orchards.

Key words: Green manure, Nitrogen supply level, C/N ratio, Fitting equation

摘要： 为了探明圆叶决明（Chamaecrista rotundifolia）降解过程果园红壤供氮水平的变化规律，本研究采用模拟培养试验，研究15℃和25℃培养果园红壤硝态氮、铵态氮、可溶性总氮、可溶性有机氮含量的变化及脲酶、蛋白酶、天冬酰胺酶活性的变化。结果表明，圆叶决明降解过程果园红壤4种可溶性氮含量均显著提高，且在培养140 d达到最大值，25℃培养的效果更佳。其中，可溶性总氮、可溶性有机氮和硝态氮含量随时间的动态变化可用三次曲线方程来拟合。圆叶决明降解过程还能显著提高脲酶、蛋白酶和天冬酰胺酶的活性，其中蛋白酶活性和脲酶活性的变化可用指数方程和三次曲线方程来拟合。本研究认为圆叶决明降解过程可提高果园红壤可溶性氮含量，因此可通过翻压圆叶决明提高土壤的供氮水平。

关键词: 绿肥, 供氮水平, C/N比, 拟合方程