不同氮肥处理对桑园土壤酶活性的影响

【目的】研究不同氮肥施用水平对桑园土壤过氧化氢酶、脲酶、酸性磷酸酶和蔗糖转化酶酶活性的影响，为桑园合理施氮和生产优质桑叶提供依据。【方法】采用田间小区试验，按不同氮肥施用水平：N1（120．75kg／ha）、N2（172．50kg／ha）和N3（207．00kg／ha）设3个处理。测定不同处理的土壤酶活性，并与桑叶产量进行相关性分析。【结果】土壤脲酶和蔗糖转化酶活性均随着施氮量的增加而增加，其中N2处理的过氧化氢酶和酸性磷酸酶活性较大。土壤蔗糖转化酶与脲酶活性、转化酶与磷酸酶活性均呈显著正相关，土壤脲酶、磷酸酶、转化酶活性与桑叶产量呈极显著正相关。【结论】合理施用氮肥能提高桑园土壤蔗糖转化酶、磷酸酶、脲酶活性；土壤脲酶和蔗糖酶活性可作为评价桑园土壤性质的指标。

Enzymatic activity of mulberry garden soil using different nitrogen fertilizer treatments

Objective]The present experiment was undertaken in order to study the effect of nitrogen fertilizer on ac- tivities of catalase, urease, acid phosphatase and invertase in soil for scientific exploitation of N fertilizer rational applica- tion and production of high quality mulberry leaves. Method ] Activities of four soil enzymes were investigated under dif- ferent ratios of N fertilizers on mulberry. There were three levels of N,namely N1（120.75 kg/ha）, N2（172.5 kg/ha） and N3 （207.0 kg/ha）in the field experiment. The soil enzymes were determined in different nitrogen fertilizer treatments to ana- lyze correlation between soil enzymatic activity and mulberry leaves yield. Result]The results showed that the urease and invertase activities were generally enhanced with bigger N ratio, but maximal acid- phosphatase and catalase activities were improved under the moderate amount of N2. Extremely significant positive correlations were found between mulberry leaf yield and soil enzyme activities including invertase, urease and acid phosphatase. The invertase activity was closely interrelated to the activity of phosphatase and urease. Conclusion ]Rationalized nitrogen fertilizer could improve the activity of invertase, phosphatase and urease. Soil urease and invertase could be used as indicators for mulberry garden soil ap- praisal.