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| Effects of different long-term nitrogen addition on soil microbial diversity of Stipa baicalensis steppe in Inner Mongolia, China |
| Received:September 30, 2016 |
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| KeyWord:Stipa baicalensis steppe;nitrogen addition;soil microbial biomass;soil microbial diversity |
| Author Name | Affiliation | E-mail | | LIU Hong-mei | Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | | | ZHANG Hai-fang | Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | | | HUANGFU Chao-he | Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | | | LI Jie | Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | | | ZHOU Guang-fan | Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | | | YANG Dian-lin | Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China | yangdianlin@caas.cn |
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| Abstract: |
| To reveal the responses of soil microbial biomass carbon, soil microbial nitrogen and functional diversity of soil microbe to long term nitrogen additions in Stipa baicalensis steppe, chloroform fumigation extraction method and Biolog Ecoplate were used to study the changes in soil microbial diversity under different N treatments, including N0(0 kg N·hm-2), N15(15 kg N·hm-2), N30(30 kg N·hm-2), N50(50 kg N·hm-2), N100(100 kg N·hm-2), N150(150 kg N·hm-2), N200(200 kg N·hm-2), N300(300 kg N·hm-2). Soil samples were separately collected from the 0~10 cm and 10~20 cm soil layer. The results showed that long-term applications of inorganic nitrogen reduced the soil microbial biomass carbon, while higher nitrogen treatments enhanced the microbial biomass nitrogen, thus significantly reduced the microbial quotient. The AWCD values of the soil microbial communities in 0~10 cm soil layer varied as follows:N50 > N30 > N100 > N15 > N0 > N200 > N150 > N300. Within same nitrogen treatment, soil microbial biomass carbon and microbial biomass nitrogen and the overall trend AWCD value in 0~10 cm soil layer was higher than those in 10~20 one. At 0~10 cm soil layer, higher nitrogen treatments(N100,N150, N200, N300) reduced the Shannon index and increased the evenness index, but not for dominance index. Principal component analysis showed that there were very significant differences between higher nitrogen treatments and lower nitrogen treatments and the control in the carbon utilization ability of soil microbial community. Soil parameters, including pH, total nitrogen, total phosphorus, microbial biomass N, microbial quotient, microbial biomass C/N and nitrate nitrogen, had close relationships with microbial functional diversity. Moreover, 100 kg N·hm-2 was the threshold with which the effect on microbial activity shift from stimulation to inhibition after long-term nitrogen addition in the study area. |
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