中文摘要：

[Objective]The present experiment was undertaken to investigate the effects of different nitrogen fertilizer application levels on soil enzymatic activities in mulberry gardens,thus providing reference for rational application of nitrogen fertilizer and production of high-quality mulberry leaves. [Method]Field experiments were conducted with three different nitrogen fertilizer application levels: N1(120.75 kg /hm2),N2(172.5 kg /hm2),and N3(207 kg /hm2). Activities of catalase,urease,acid phosphatase and invertase in soil applied with different amount of nitrogen fertilizer were determined to analyze the correlation between soil enzymatic activities and mulberry leaf yield. [Result]Activities of urease and invertase in soil were improved with the increasing application level of nitrogen fertilizer; activities of catalase and acid phosphatase reached the highest in treatment N2. Activities of invertase and urease in soil exhibited significant positive correlations; activities of invertase and phosphatase exhibited significant positive correlations; extremely significant positive correlations were found between mulberry leaf yield and activities of urease,phosphatase and invertase in soil. [Conclusion]Rationally applying nitrogen fertilizer can improve activities of invertase,phosphatase and urease in mulberry gardens; activities of urease and invertase in soil can be used as indicators to evaluate soil properties in mulberry gardens.

英文摘要：

[ Objective] The present experiment was undertaken to investigate the effects of different nitrogen fertilizer application levels on soil enzymatic activities in mulberry gardens, thus providing reference for rational application of nitrogen fertilizer and production of high-quality mulberry leaves. [Method] Field experiments were conducted with three different nitrogen fertilizer application levels： N, （ 120.75 kg/hm2 ）, N2 （ 172.5 kg/hm2 ）, and N3 （207 kg/hm2 ）. Activities of catalase, urease, acid phosphatase and invertase in soil applied with different amount of nitrogen fertilizer were determined to analyze the correlation between soil enzymatic activities and mulberry leaf yield. [ Result] Activities of urease and invertase in soil were improved with the increasing application level of nitrogen fertil- izer; activities of catalase and acid phosphatase reached the highest in treatment N2. Activities of invertase and urease in soil exhibited significant positive correla- tions; activities of invertase and phosphatase exhibited significant positive correlations; extremely significant positive correlations were found between mulberry leaf yield and activities of urease, phosphatase and invertase in soil. [ Conclusion] Rationally applying nitrogen fertilizer can improve activities of invertase, phosphatase and urease in mulberry gardens ; activities of urease and invertase in soil can be used as indicators to evaluate soil properties in mulberry gardens.