Variation in Soil Enzyme Activities under Long-term Fertilization of Tea Garden in Red-yellow Soil Area

The aim of this study was to show the effects of long-term fertilization on the activities of protease,urease,invertase,catalase and phosphatase of the tea garden soil in red-yellow soil area.It consisted of six treatments: no fertilization,the whole rate of chemical fertilizer,half rate of chemical fertilizer + half rate of organic fertilizer,the whole rate of organic fertilizer,the whole rate of chemical fertilizer + leguminous green manure and half rate of chemical fertilizer + half rate of organic fertilizer + leguminous green manure.Results indicated that: The activities of protease,urease and phosphatase in soil were enhanced by all those treatments,especially by half rate of chemical fertilizer + half rate of organic fertilizer + leguminous green manure treatment,the protease activity was increased 2.82 times,urease by 7.73 times and phosphatase by 0.33 times compared to those under no fertilization treatment,while the activities of those enzymes in the whole rate of chemical fertilizer treatment were less than those in half rate of chemical fertilizer + half rate of organic fertilizer + leguminous green manure treatment.In addition,organic matter,soil total N and P,hydrolysable N,available P and K,soil water content,cation exchange capacity,plant height and tea yield were highly positively correlated with individual enzymes such as protease,urease and phosphatase rather than catalase activity,respectively.It is concluded that the protease,urease and phosphatase showed the most sensitive to the treatments,suggesting that those enzymes should be used as sensitive indicators of variation in soil quality and the growth vigor of tea plant induced by different fertilization treatment.Overall,a faster nitrogen and phosphorus turn-over is found under half rate of chemical fertilizer + half rate of organic fertilizer + leguminous green manure treatment,which is beneficial to increase the supply of these nutrients to tea plant.