Carbon mineralization and microbial activity in agricultural topsoil and subsoil as regulated by root nitrogen and recalcitrant carbon concentrations

TitleCarbon mineralization and microbial activity in agricultural topsoil and subsoil as regulated by root nitrogen and recalcitrant carbon concentrations
Publication TypeJournal Article
Year of Publication2018
AuthorsLiang Z., Elsgaard L., Nicolaisen M.H, Lyhne-Kjaerbye A., Olesen J.E
JournalPlant and SoilPlant and SoilPlant and Soil
Volume433
Pagination65-82
Date PublishedDec
Type of ArticleArticle
ISBN Number0032-079X
Accession NumberWOS:000449754900006
KeywordsAgriculture, Carbon mineralization, community-level, depth, dynamics, dystric cambisol, ecosystem, forest, Lignin, management, nitrogen, physiological profiles, Plant Sciences, Root chemistry, sequestration, soil organic-carbon, Subsoil
Abstract

Aims Mechanisms of subsoil carbon sequestration from deep-rooted plants are elusive, but may contribute to climate change mitigation. This study addressed the role of root chemistry on carbon mineralization and microbiology in a temperate agricultural subsoil (60 and 300cm depth) compared to topsoil (20cm depth). Methods Roots from different plant species were chemically characterized and root-induced CO2 production was measured in controlled soil incubations (20weeks). Total carbon losses, beta-glucosidase activity, carbon substrate utilization, and bacterial gene copy numbers were determined. After 20weeks, resultant carbon mineralization responses to mineral nitrogen (N) were tested. Results Root-induced carbon losses were significantly lower in subsoils (32-41%) than in topsoil (58%). Carbon losses varied according to root chemistry and were mainly linked to root N concentration for subsoils and to lignin and hemicellulose concentration for topsoil. Increases in -glucosidase activity and bacterial numbers in subsoils were also linked to root N concentration. Added mineral N preferentially stimulated CO2 production from roots with low concentrations of N, lignin and hemicellulose. Conclusions The results were compatible with a concept of N availability and chemically recalcitrant root compounds interacting to control subsoil carbon decomposition. Implications for carbon sequestration from deep-rooted plants are discussed.

Short TitlePlant SoilPlant Soil
Alternate JournalPlant Soil