Role of Microbial Assimilation of Soil NO3- in Reducing Soil NO3- Concentration

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Supported by the National Natural Science Foundation of China (Nos. 41671231and 41571294) and the National Key Research and Development Program of China (Nos. 2017YFD0200106 and 2017YFD0800103)

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    NO3- accumulation in the soil would trigger N losses through runoff, leaching and N2O emission. It is, therefore, of particular importance to take appropriate nitrogen (N) management strategies to reduce soil NO3- accumulation, and hence to enhance N use efficiency and reduce N losses to the environment. Application of nitrification inhibitor (NI) has been demonstrated to be effective in reducing soil NO3- concentration, NO3- leaching and N2O emission, and simultaneously increasing crop yield. However, there is an indisputable fact that NI application increases ammonia (NH3) emission and causes NI contamination. As a matter of fact, soil NO3- concentration varies with NO3- generation (nitrification) and consumption (assimilation) rates in aerobic conditions. Under the influence of the viewpoint that soil microbes prefer NH4 -N for their growth, it is commonly held that soil microbes rarely use NO3- in farmlands. Consequently, the study on processes of soil microbial NO3- assimilation has been neglected to a certain extent. The process of soil microbial NO3- assimilation is found to be unique in advantage. It turns NO3- into microbial biomass N for temporary storage before mineralization to be available to crops for a longer season or crops in the following season. There is no doubt that soil microbial NO3- immobilization is stimulated by specific extraneous C input, which deserves more attention in future studies concerning how to reduce soil NO3- accumulation. Further studies should primarily focus on the following several aspects: (1) to elucidate mechanism of the microbe driving NO3- assimilation under elevated C availability, (2) to explore how to control microbial assimilation and remineralization of NO3- to match soil N supply with crop N demand and reduce N losses, and (3) to explore how to avoid stimulating denitrification and associated N losses while enhancing microbial NO3- assimilation under the condition of sufficient C supply.

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CHENG Yi, HUANG Rong, YU Yunfei, WANG Shenqiang. Role of Microbial Assimilation of Soil NO3- in Reducing Soil NO3- Concentration[J]. Acta Pedologica Sinica,2017,54(6):1326-1331.

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  • Received:April 11,2017
  • Revised:August 11,2017
  • Adopted:August 18,2017
  • Online: September 04,2017
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