Land use driven change in soil pH affects microbial carbon cycling processes

• Published in: Nature communications Vol. 9; no. 1; pp. 3591 - 10
• Main Authors: Malik, Ashish A., Puissant, Jeremy, Buckeridge, Kate M., Goodall, Tim, Jehmlich, Nico, Chowdhury, Somak, Gweon, Hyun Soon, Peyton, Jodey M., Mason, Kelly E., van Agtmaal, Maaike, Blaud, Aimeric, Clark, Ian M., Whitaker, Jeanette, Pywell, Richard F., Ostle, Nick, Gleixner, Gerd, Griffiths, Robert I.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04-09-2018; Nature Publishing Group; Nature Portfolio
• Subjects: 140/58; 49/75; 631/158/855; 631/326/171/1818; 704/158/2445; 704/47/4113; Accumulation; Acidic soils; Agriculture; Amplification; Biomass; Carbon - metabolism; Carbon content; Carbon cycle; Carbon Dioxide - metabolism; Carbon Isotopes - analysis; Carbon Isotopes - metabolism; Carbon sequestration; Decomposition; Geographical distribution; Grassland; Humanities and Social Sciences; Hydrogen-Ion Concentration; Land management; Land use; Microbial Consortia - physiology; Microorganisms; multidisciplinary; Organic matter; Organic soils; pH effects; Resource management; Science; Science (multidisciplinary); Soil - chemistry; Soil management; Soil Microbiology; Soil microorganisms; Soil organic matter; Soil pH; Topsoil; United Kingdom; United Kingdom
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-05980-1

Soil microorganisms act as gatekeepers for soil–atmosphere carbon exchange by balancing the accumulation and release of soil organic matter. However, poor understanding of the mechanisms responsible hinders the development of effective land management strategies to enhance soil carbon storage. Here we empirically test the link between microbial ecophysiological traits and topsoil carbon content across geographically distributed soils and land use contrasts. We discovered distinct pH controls on microbial mechanisms of carbon accumulation. Land use intensification in low-pH soils that increased the pH above a threshold (~6.2) leads to carbon loss through increased decomposition, following alleviation of acid retardation of microbial growth. However, loss of carbon with intensification in near-neutral pH soils was linked to decreased microbial biomass and reduced growth efficiency that was, in turn, related to trade-offs with stress alleviation and resource acquisition. Thus, less-intensive management practices in near-neutral pH soils have more potential for carbon storage through increased microbial growth efficiency, whereas in acidic soils, microbial growth is a bigger constraint on decomposition rates.
Land use intensification could modify microbial activity and thus ecosystem function. Here, Malik et al. sample microbes and carbon-related functions across a land use gradient, demonstrating that microbial biomass and carbon use efficiency are reduced in human-impacted near-neutral pH soils.