Qin Jie, Liu Hongmei, Zhao Jianning, Wang Hui, Zhang Haifang, Yang Dianlin, Zhang Naiqing
Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, MARA, Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety, Tianjin 300191, China.
Department of Ecology and Landscape Architecture, Dezhou University, Dezhou 253023, China.
Microorganisms. 2020 Feb 26;8(3):326. doi: 10.3390/microorganisms8030326.
Grassland soil organic carbon (SOC) accounts for 15.5% of the SOC in reservoirs of terrestrial carbon (C) and is a major component of the global C cycle. Current and future reactive N deposited on grassland soils may alter biogeochemical processes and soil microbes. Microorganisms perform most of the decomposition on Earth and shift SOC accumulation. However, how variation in the identity and composition of the bacterial community influences SOC is far from clear. The objective of this study is to investigate the responses of SOC concentration to multiple rates of N addition as well as the roles of bacteria in SOC accumulation. We studied SOC storage and bacterial community composition under N addition treatments (0, 1.5, 3.0, 5.0, 10.0, 15.0, 20.0, and 30.0 g N·m yr) in a 6-yr field experiment in a temperate grassland. We determined the soil inorganic nitrogen concentration and pH in a 0-10 cm soil layer. We used high-throughput genetic sequencing to detect bacteria. N addition led to significant increases in the concentrations of SOC. N addition reduced the soil pH but increased the NO-N and NH-N levels. The bacterial diversity was highest under low nitrogen addition. N addition increased the relative abundance of Proteobacteria, and Proteobacteria became the second dominant phylum under high N addition. Structural equation modeling further revealed that soil pH and bacterial community structure have an impact on SOC under N deposition. Nitrogen-regulated SOC is associated with Proteobacteria and Planctomycetes. These findings suggest that N deposition may alter the SOC content, highlighting the importance of understanding changes in the bacterial community for soil nutrients under N deposition.
草原土壤有机碳（SOC）占陆地碳（C）储存库中SOC的15.5%，是全球碳循环的主要组成部分。当前和未来沉降在草原土壤上的活性氮可能会改变生物地球化学过程和土壤微生物。微生物在地球上进行大部分的分解作用并影响SOC的积累。然而，细菌群落的身份和组成变化如何影响SOC尚不清楚。本研究的目的是调查SOC浓度对多种施氮速率的响应以及细菌在SOC积累中的作用。我们在温带草原进行了为期6年的田间试验，研究了不同施氮处理（0、1.5、3.0、5.0、10.0、15.0、20.0和30.0 g N·m⁻²·yr⁻¹）下的SOC储存和细菌群落组成。我们测定了0-10 cm土层的土壤无机氮浓度和pH值。我们使用高通量基因测序来检测细菌。施氮导致SOC浓度显著增加。施氮降低了土壤pH值，但提高了NO₃-N和NH₄-N水平。在低氮添加条件下细菌多样性最高。施氮增加了变形菌门的相对丰度，在高氮添加条件下变形菌门成为第二优势菌门。结构方程模型进一步揭示，在氮沉降条件下，土壤pH值和细菌群落结构对SOC有影响。氮调控的SOC与变形菌门和浮霉菌门有关。这些发现表明，氮沉降可能会改变SOC含量，突出了了解氮沉降下细菌群落变化对土壤养分的重要性。
