Impacts of increased N use and precipitation on microbial C utilization potential in the semiarid grassland of Inner Mongolia

Plant community structure and composition have been noted to be sensitive to climate change and N deposition in the semiarid grassland of northern China. Despite this fact, little research has been conducted on the response of microbial community in this semi-arid grassland region. The aim of this study was to assess the variations in soil microbial C utilization potential under future scenarios of changes in precipitation and N deposition in the semiarid grassland of northern China. C utilization potential of soil microbial community was determined at community-based physiological profiles in a 3-year field experiment. To simulate changes in precipitation and N deposition in the area under the future scenario, increased precipitation and N treatments were performed in a experiment field in the semiarid grassland at Inner Mongolia. Based on the study, N application and increased precipitation changed the soil environment that in turn significantly influenced soil microbial C utilization. While increased precipitation increased soil moisture and soil organic matter, N application or N application combined with increased precipitation increased soil dissolved inorganic N and decreased soil pH in the semiarid grassland of the study area. Neither sole application of N nor increased precipitation influenced soil microbial C utilization potential. Positive interactions between increased precipitation and N application enhanced microbial C utilization potential, which implied that microbial C utilization potential was somewhat inactive until N and water were available in sufficient amounts. The response of soil microbial community to increased precipitation and N application confirmed the hypothesis that combined increase in precipitation and N application influenced microbial communities in semiarid grasslands. This enhanced microbial C utilization potential with possible acceleration of the C cycle due to future increases in precipitation and N deposition in the semiarid grassland of North China. Correlations between soil microbial C utilization potential and soil/plant factors suggested that soils, microbes and plants reacted with simultaneously increase in precipitation and N application.