Journal
SOIL BIOLOGY & BIOCHEMISTRY
Volume 47, Issue -, Pages 67-77Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.soilbio.2011.05.012
Keywords
N addition; Polyphenol oxidase; Peroxidase; Invertase; Urease; Alkaline phosphatase; Microbial biomass; CLPP
Categories
Funding
- Chinese Academy of Sciences [KZCX2-YW-336]
- National Natural Science Foundation of China [41001181]
- National Basic Research Program [2009CB825104]
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Identifying the patterns of soil microbial responses to increasing nitrogen (N) availability are important since microbial processes are related to the potential nutrient transformations. The effects of the addition of N to the soil microbial community of the Gurbantunggut Desert, China, are described in this paper. The study was conducted over a two-year period with trials commencing at the beginning of each growing season. Soil enzyme activity, microbial biomass and microbial community level physiological profile (CLPP) were determined at 0-5 cm and 5-10 cm soil depths. Nitrogen was added to the soil at five rates plus a control, i.e. 0, 0.5, 1, 3, 6 and 24 g N m(-2) y(-1). We hypothesized that soil enzyme activities and microbial biomass N (MBN) would firstly increase and then decrease, and CLPP would be altered with increasing N addition, due to the deleterious effects of higher N addition upon microbial activity. Because of the relatively higher organic matter in the upper depth of soil layers, we further hypothesized that the responses of microbial activities in the 0-5 cm depth would be more marked than at 5-10 cm. In partial support of our hypothesis, soil enzyme activities, microbial biomass and nutrient concentrations responded to N addition with the most significant changes occurring in the 0-5 cm soil depth. Addition of N resulted in an increase in MBN and a decrease in urease activity. Invertase and alkaline phosphatase (AIP) activities increased at low doses of N addition and showed a decrease at higher doses. There was no evidence of change in oxidative enzyme activity at low N treatments but activity decreased at high N additions. However, the CLPP was not affected by N addition. The results of this study suggest that N supplementation in this desert soil may affect C transformation, increase availability of N and P. and immobilize N in the microbial biomass. Responses of the enzyme activity to N supplementation occurred within the context of an apparently stable or unresponsive microbial community structure. (C) 2011 Published by Elsevier Ltd.
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