Long-term management changes in topsoil and subsoil organic carbon and nitrogen dynamics in a temperate agricultural system

A - Papers appearing in refereed journals

Gregory, A. S., Dungait, J. A. J., Watts, C. W., Bol, R., Dixon, E. R., White, R. P. and Whitmore, A. P. 2016. Long-term management changes in topsoil and subsoil organic carbon and nitrogen dynamics in a temperate agricultural system. European Journal of Soil Science. 67 (4), pp. 421-430.

AuthorsGregory, A. S., Dungait, J. A. J., Watts, C. W., Bol, R., Dixon, E. R., White, R. P. and Whitmore, A. P.
Abstract

Soil organic carbon (SOC) and nitrogen (N) contents are controlled partly by plant inputs that can be manipulated in agricultural systems. Although SOC and N pools occur mainly in the topsoil (upper 0.30 m), there are often substantial pools in the subsoil that are commonly assumed to be stable. We tested the hypothesis that contrasting long-term management systems change the dynamics of SOC and N in the topsoil and subsoil (to 0.75 m) under temperate conditions. We used an established field experiment in the UK where control grassland was changed to arable (59 years before) and bare fallow (49 years before) systems. Losses of SOC and N were 65 and 61% under arable and 78 and 74% under fallow, respectively, in the upper 0.15m when compared with the grass land soil, whereas at 0.3-0.6-m depth losses under arable and fallow were 41 and 22% and 52 and 35%, respectively. The stable isotopes C-13 and N-15 showed the effects of different treatments. Concentrations of long-chain n-alkanes C-27, C-29 and C-31 were greater in soil under grass than under arable and fallow. The dynamics of SOC and N changed in both topsoil and subsoil on a decadal time-scale because of changes in the balance between inputs and turnover in perennial and annual systems. Isotopic and geochemical analyses suggested that fresh inputs and decomposition processes occur in the subsoil. There is a need to monitor and predict long-term changes in soil properties in the whole soil profile if soil is to be managed sustainably.

KeywordsSoil Science
Year of Publication2016
JournalEuropean Journal of Soil Science
Journal citation67 (4), pp. 421-430
Digital Object Identifier (DOI)doi:10.1111/ejss.12359
Open accessPublished as ‘gold’ (paid) open access
Funder project or codeCropping Carbon (CC) [ISPG]
Delivering Sustainable Systems (SS) [ISPG]
FunderBiotechnology and Biological Sciences Research Council
ISSN13510754
PublisherWiley

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