1. Biotic and abiotic nitrogen immobilization in soil incorporated with crop residue
- Author
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Zhao Fengliang, Zhu Tongbin, Zhang Zhongyi, Cao Yansheng, and Xiao Huayun
- Subjects
Abiotic component ,Crop residue ,Microorganism ,Soil organic matter ,fungi ,Microbial metabolism ,food and beverages ,Soil Science ,Biomass ,04 agricultural and veterinary sciences ,chemistry.chemical_compound ,chemistry ,Soil pH ,Environmental chemistry ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Ammonium ,Agronomy and Crop Science ,Earth-Surface Processes - Abstract
Incorporating crop residue favors biotic and abiotic nitrogen (N) immobilization, which can effectively conserve active N in soil. Here we summarize the occurrence characteristics of biotic and abiotic N immobilization and affecting factors, and then identify a general pattern of the relative importance of the two processes in soil incorporated with crop residue. When microorganisms decompose crop residue for a source of energy and carbon (C) to support their metabolism, they need N to build cellular components, resulting in N immobilization in biomass. Alternatively, N can be incorporated into soil organic matter (SOM) through the following known mechanisms: ammonium (NH4+) fixation by clay minerals, condensation of ammonia (NH3) with phenol or quinone rings, and nitrosation of nitrite (NO2-) with phenolic compounds. The biotic and abiotic contribution to N immobilization is significantly controlled by soil properties and crop residual quality. When a large fraction of C is in the form of labile organic compounds, biotic N immobilization may be important. In contrast, high fraction of lignin-derived phenolic compounds or other recalcitrant organic compounds facilitates abiotic N immobilization. In the N-limited soil, the increase in N availability contributes to microbial activity, which would stimulate biotic processes. However, when microbial metabolism switches from N-limited to C-limited due to the increase in N availability, abiotic processes become important. Abiotic processes even predominate over biotic processes under N-enriched conditions. The relative roles of biotic or abiotic N immobilization in soil incorporated with crop residue are dependent on the availability of C relative to N and soil N availability. Carbon and N availability in turn is related to their forms. Moreover, N availability is affected by soil pH. The mechanisms by which N is immobilized determine the fate of immobilized N and are of vital importance for the management of N availability and losses through combining N fertilizer with crop residue. More investigation is necessary to quantify the contribution of biotic and abiotic processes during the decomposition of crop residue and to determine the factors affecting N immobilization in the field.
- Published
- 2020