Characteristics of Soil Micro-ecological Environment at Different Growth Stages of Poplar Plantation under Continuous Cropping

Dynamics of soil micro-ecological environment at different growth stages of poplar plantation were studied in Zhaoxian town and Qiaoshan town of Ju county,Shandong province.The results showed: with the plantation ages increased, soil physics property became worse,and then it became better than before.However,pH value decreased with plantation ages increased.Contents of soil nutrients and the activity of soil urease increased firstly,and then decreased.Peroxidase activity and polyphenol oxidase activity decreased with plantation ages increased;however,catalase activity was not a significant law.With the poplar plantation ages increased,the number of bacteria and actinomyces and total number of soil microbes increased;however,the number of fungi was not a significant law.Compared with different soil layers,soil physical properties of the bottom layer were worse than the top layer.With the depth of soil layer increased,the contents of soil nutrients were decreased other than soil available P and soil micro-element Fe.The activity of soil urease was decreased with the depth of soil layer increased;however,catalase activity,peroxidase activity and polyphenol oxidase activity were not significant law.Especially,compared with the two experimental sites,catalase activity showed reverse trends.