Impacts of urea N addition on soil microbial community in a semi-arid temperate steppe in northern China

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• 作者：Naili Zhang ; Shiqiang Wan ; Linghao Li ; Jie Bi ; Mingming Zhao and Keping Ma
• 关键词：CLPP ; Microbial biomass ; N addition ; Net N mineralization ; Nitrification
• 刊名：Plant and Soil
• 出版年：2008
• 出版时间：October, 2008
• 年：2008
• 卷：311
• 期：1-2
• 页码：19-28
• 全文大小：249.7 KB

文摘

Nitrogen (N) addition has been well documented to decrease plant biodiversity across various terrestrial ecosystems. However, such generalizations about the impacts of N addition on soil microbial communities are lacking. This study was conducted to examine the impacts of N addition (urea-N fertilizer) on soil microbial communities in a semi-arid temperate steppe in northern China. Soil microbial biomass carbon (C), biomass N (MBN), net N mineralization and nitrification, and bacterial and fungal community level physiological profiles (CLPP) along an N addition gradient (0–64 g N m−2 year−1) were measured. Three years of N addition caused gradual or step increases in soil NH₄-N, NO₃-N, net N mineralization and nitrification in the early growing season. The reductions in microbial biomass under high N addition levels (32 and 64 g N m−2 year−1) are partly attributed to the deleterious effects of soil pH. An N optimum between 16 and 32 g N m−2 year−1 in microbial biomass and functional diversity exists in the temperate steppe in northern China. Similar N loading thresholds may also occur in other ecosystems, which help to interpret the contrasting observations of microbial responses to N addition.