Stabilization of microbial residues in soil organic matter after two years of decomposition

Publication date: Available online 25 November 2019Source: Soil Biology and BiochemistryAuthor(s): Chao Wang, Xu Wang, Guangting Pei, Zongwei Xia, Bo Peng, Lifei Sun, Jian Wang, Decai Gao, Shidong Chen, Dongwei Liu, Weiwei Dai, Ping Jiang, Yunting Fang, Chao Liang, Nanping Wu, Edith BaiAbstractMicrobially-derived nitrogen (N) has been considered as one of important contributors to soil organic N, but few studies have quantified the rate of necromass N decomposition. Here, via an in situ incubation of 15N-labeled necromass, we found that 33.1–39.5% of the initial 15N stabilized in the soil as non-living organic N after 803 days of incubation. Bacterial, fungal, and actinobacterial necromass N showed similar decomposition pattern and mean residence time. The decomposition of microbial necromass N was best simulated by a two-pool model where a labile pool decomposed rapidly (0.4 years), and a more recalcitrant pool decomposed at a much slower rate. This finding contrasted with the decomposition of plant litter N, which was better simulated by a single-pool model. The stabilization of necromass N in soils after more than two years suggests the important contribution of microbial residues to soil organic N, which is most likely due to mineral protection from decomposition.
Source: Soil Biology and Biochemistry - Category: Biology Source Type: research