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Wang X, Wang J, Zou Y, Bie Y, Mahmood A, Zhang L, Liao L, Song Z, Liu G, Zhang C. Urea fertilization increased CO 2 and CH 4 emissions by enhancing C-cycling genes in semi-arid grasslands. J Environ Manage 2024; 356:120718. [PMID: 38537467 DOI: 10.1016/j.jenvman.2024.120718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 03/10/2024] [Accepted: 03/19/2024] [Indexed: 04/07/2024]
Abstract
Global climate change is predicted to increase exogenous N input into terrestrial ecosystems, leading to significant changes in soil C-cycling. However, it remains largely unknown how these changes affect soil C-cycling, especially in semi-arid grasslands, which are one of the most vulnerable ecosystems. Here, based on a 3-year field study involving N additions (0, 25, 50, and 100 kg ha-1 yr-1 of urea) in a semi-arid grassland on the Loess Plateau, we investigated the impact of urea fertilization on plant characteristics, soil properties, CO2 and CH4 emissions, and microbial C cycling genes. The compositions of genes involved in C cycling, including C fixation, degradation, methanogenesis, and methane oxidation, were determined using metagenomics analysis. We found that N enrichment increased both above- and belowground biomasses and soil organic C content, but this positive effect was weakened when excessive N was input (N100). N enrichment also altered the C-cycling processes by modifying C-cycle-related genes, specifically stimulating the Calvin cycle C-fixation process, which led to an increase in the relative abundance of cbbS, prkB, and cbbL genes. However, it had no significant effect on the Reductive citrate cycle and 3-hydroxypropionate bi-cycle. N enrichment led to higher soil CO2 and CH4 emissions compared to treatments without added N. This increase showed significant correlations with C degradation genes (bglA, per, and lpo), methanogenesis genes (mch, ftr, and mcr), methane oxidation genes (pmoA, pmoB, and pmoC), and the abundance of microbial taxa harboring these genes. Microbial C-cycling genes were primarily influenced by N-induced changes in soil properties. Specifically, reduced soil pH largely explained the alterations in methane metabolism, while elevated available N levels were mainly responsible for the shift in C fixation and C degradation genes. Our results suggest that soil N enrichment enhances microbial C-cycling processes and soil CO2 and CH4 emissions in semi-arid ecosystems, which contributes to more accurate predictions of ecosystem C-cycling under future climate change.
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Affiliation(s)
- Xiaojun Wang
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Shaanxi, 712100, PR China; Institute of Soil and Water Conservation, Chinese Academy of Science, Shaanxi, 712100, PR China
| | - Jie Wang
- College of Forestry, Guizhou University, Guiyang, 550025, PR China
| | - Yanuo Zou
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Shaanxi, 712100, PR China; Institute of Soil and Water Conservation, Chinese Academy of Science, Shaanxi, 712100, PR China
| | - Yujing Bie
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Shaanxi, 712100, PR China; Institute of Soil and Water Conservation, Chinese Academy of Science, Shaanxi, 712100, PR China
| | - Athar Mahmood
- Department of Agronomy, University of Agriculture Faisalabad, Faisalabad, 38000, Pakistan
| | - Lu Zhang
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Shaanxi, 712100, PR China; Institute of Soil and Water Conservation, Chinese Academy of Science, Shaanxi, 712100, PR China
| | - Lirong Liao
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Shaanxi, 712100, PR China; Institute of Soil and Water Conservation, Chinese Academy of Science, Shaanxi, 712100, PR China
| | - Zilin Song
- College of Natural Resources and Environment, Northwest A&F University, Shaanxi, 712100, PR China
| | - Guobin Liu
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Shaanxi, 712100, PR China; Institute of Soil and Water Conservation, Chinese Academy of Science, Shaanxi, 712100, PR China.
| | - Chao Zhang
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Shaanxi, 712100, PR China; Institute of Soil and Water Conservation, Chinese Academy of Science, Shaanxi, 712100, PR China.
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