Study On Soil Microbial Biomass Nitrogen, Phosphorus And Enzyme Activities In Poplar Plantation

In order to explore the mechanism of soil fertility degradation in the different successive rotations of poplar plantations, the poplar plantations with the different ages and different rotations (Farmland, the first rotation of six-year-old, the first rotation of ten-year-old, the second rotation of five-year-old and the second of eight-year-old) and the different soil texture were selected to study their soil microbial biomass nitrogen (MB-N), microbial biomass phosphorus (MB-P) and soil enzymes activities as well as their annual dynamics in Sihong County, Suqian City, Jiangsu province in this paper. To explore the reason of soil fertility degradation in different successive rotations of poplar plantatons ,the poplar plantation with the different ages,to provide some basic data for the poplar management and poplar industry.The main results were showed as follow:1. The content of soil MB-N in poplar plantations was between 17.40 mg/kg～41.68 mg/kg,average is 29.92 mg/kg,MB-P in poplar plantations was between 9.98 mg/kg～18.80 mg/kg,average is14.74 mg/kg,urease activities in poplar plantations was between59.78 ug/g～156.17 ug/g,average is 82.48 ug/g and protein activities in poplar plantations was between 2.97 ug/g,～4.99 ug/g,average is 4.00 ug/g.2. The content of soil MB-N, MB-P and enzymes activities in poplar plantations were obviously decreased with the increase of poplar plantation ages.3. Studies show that the MB-N,MB-P of different ages and different passages showd a decreacing trend with the increasing generations.4. Studies show that the MB-N,MB-P of different ages and different passages showd a decreacing trend with the increasing soil depth,as top soil>subsurface soil>deep soil.5.The seasonal changes of MB-N ,MB-P and enzyme activity were obvious,MB-N and MB-P showed a trend of ruducing to increasing from February to December,the minmum value were in August and October; enzyme activity showed a trend of'high- low-high-low-high', the minmum value were in August and October.6.MB-N and MB-P in different ages and passages has significant changes,The changes of soil enzyme activities were quite too.7. MB-N ,MB-P and enzyme activity showed positive correlation with the soil physical and chemical properties.8.In different plantation soil,MB-N,MB-P all showed highly significant positive correlation;MB-N and urease all showed a positive correlation;MB-P and urease all showed highly significant positive correlation;MB-P and protein showed positive correlation;urease and protein showed highly significant positive correlation.