Journal of Pure and Applied MicrobiologyVol. 8 No. 2

Intra- and Inter-annual Variation of Soil Microbial and Enzymatic Response to Water and Nitrogen Addition in a Chinese Semi-arid Steppe

Liangjie Sun1,2, Yunshe Dong1, Yuchun Qi1*, Yating He1,3, Qin Peng1, Xinchao Liu1,2, Junqiang Jia1,2, Shufang Guo1,2, and Congcong Cao1,2

1Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Science, No. 11A, Datun Road, Chaoyang District, Beijing 100101, China. 2Graduate University of Chinese Academy of Science, No.19A, Yuquan Road, Beijing 100049, China. 3Ministry of Agriculture Key Laboratory of Crop Nutrition and Fertilization, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.

Received on 09 January 2014 and accepted on 18 March 2014

 

ABSTRACT

The knowledge about the effects of precipitation change and N deposition on soil microbe and enzymes is still limited for now. A field experiment was conducted with water- and N-addition treatments in a Chinese semi-arid grassland, and the dynamic changes of invertase, b-glucosidase, urease, dehydrogenase and substrate-induced respiration were monitored in 2011and 2012 to investigate the response of soil enzymes and microorganisms to increasing precipitation and N deposition. The results showed that the tested enzymes and substrate-induced respiration had significant intra- and inter-annual variations. The tested enzyme activities peaked at the beginning of the growing season in 2012, when the soil inorganic N was lower than that in 2011, but the substrate-induced respiration was not synchronous with the enzymes. Water addition had negative effect on the enzymes and substrate-induced respiration. N addition improved the activities of C-acquiring enzymes but decreased the activity of N-acquiring enzyme in the lower-precipitation year, while stimulated all four enzymes in the higher-precipitation year. There was a significant interaction between water addition and N addition on soil enzymes and microorganisms. This study highlighted that the inter-annual fluctuation of climates could be a non-ignorable interference to the effects of water and N treatments on soil extracellular enzymes and microorganisms.

Keywords : Water addition, N addition, enzyme, substrate-induced respiration, intra/inter-annual variation.