Nitrogen input enhances microbial carbon use efficiency by altering plant–microbe–mineral interactions. (1st June 2022)

• Record Type: Journal Article
• Authors: Feng, Xuehui; Qin, Shuqi; Zhang, Dianye; Chen, Pengdong; Hu, Jie; Wang, Guanqin; Liu, Yang; Wei, Bin; Li, Qinlu; Yang, Yuanhe; Chen, Leiyi
• Is Part Of: Global change biology. Volume 28:Number 16(2022)
• Page Start: 4845
• Page End: 4860
• Publication Date: 2022-06-01
• Subjects: carbon use efficiency -- carbon–nitrogen interaction -- microbial growth -- microbial physiology -- mineral protection -- soil C accessibility; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.16229
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: Microbial growth and respiration are at the core of the soil carbon (C) cycle, as these microbial physiological performances ultimately determine the fate of soil C. Microbial C use efficiency (CUE), a critical metric to characterize the partitioning of C between microbial growth and respiration, thus controls the sign and magnitude of soil C‐climate feedback. Despite its importance, the response of CUE to nitrogen (N) input and the relevant regulatory mechanisms remain poorly understood, leading to large uncertainties in predicting soil C dynamics under continuous N input. By combining a multi‐level field N addition experiment with a substrate‐independent 18 O‐H2 O labelling approach as well as high‐throughput sequencing and mineral analysis, here we elucidated how N‐induced changes in plant–microbial–mineral interactions drove the responses of microbial CUE to N input. We found that microbial CUE increased significantly as a consequence of enhanced microbial growth after 6‐year N addition. In contrast to the prevailing view, the elevated microbial growth and CUE were not mainly driven by the reduced stoichiometric imbalance, but strongly associated with the increased soil C accessibility from weakened mineral protection. Such attenuated organo–mineral association was further linked to the N‐induced changes in the plant community and the increased oxalic acid in the soil. These findings provide empirical evidence for the tight linkage between mineral‐associated C dynamics and microbial physiology, highlighting the need to disentangle the complex plant–microbe–mineral interactions to improve soil C prediction under anthropogenic N input. Abstract : Despite the importance of microbial carbon use efficiency (CUE) in determining the fate of soil carbon, the relevant mechanisms underlying its response to nitrogen input remain poorly understood. By using a novel substrate‐independent 18 O‐H2 O labelling approach, here we revealed that nitrogen addition significantly stimulated microbial growth and increased microbial CUE, which were dominantly shaped by the increased accessibility of soil carbon to microbial communities due to the attenuated mineral‐organic associations. This finding highlights the importance of disentangling the complex plant‐microbe‐mineral interactions for accurate prediction of soil carbon dynamics under anthropogenic nitrogen input.