PS 4-41 - Effects of simulated N deposition on soil microbial communities among three hydraulically contrasting years in a semi-arid grassland, China

Monday, August 7, 2017
Exhibit Hall, Oregon Convention Center
Yinghui Liu, College of Resources Science and Technology, Beijing Normal University, Beijing, China and Yue Li, College of Resources Science and Technology, Beijing Normal University
Background/Question/Methods Low critical load of N for grassland soil indicated its sensitivity to N deposition. With ever-increasing nitrogen (N) deposition, soil will become less limited by N availability. Annual variation of soil moisture caused by different precipitation pattern fundamentally impacts on the terrestrial ecosystem, especially semi-arid ecosystems. The joint effect of N and soil moisture on semi-arid grasslands has been reported to be significant yet inconsistent, resulting in a poor understanding of how soil microbial communities respond to N deposition and the variation of soil moisture among years.

Results/Conclusions In this study, N addition was found to be the primary factor in regulating both microbial biomass and composition, while soil moisture indirectly modified soil microbial composition by regulating soil nutrient availability. N addition shifted soil community to bacteria-dominated, but low soil moisture shifted soil community to fungi-dominated. Soil dissolved organic carbon (DOC), soil pH, C: N ratio, ammonium nitrogen and total nitrogen were significantly associated with the variation of microbial composition. Therefore, this study revealed the responses of microbial communities to both factors of N deposition and hydraulically contrasting years, and explored the associations among environmental variables and microbial communities in the semi-arid grassland of China.