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Applied and Environmental Soil Science
Volume 2012 (2012), Article ID 743413, 10 pages
http://dx.doi.org/10.1155/2012/743413
Research Article

Fate in Soil of Flavonoids Released from White Clover (Trifolium repens L.)

Department of Agroecology, Aarhus University, Forsøgsvej 1, Flakkebjerg, 4200 Slagelse, Denmark

Received 15 June 2011; Accepted 23 September 2011

Academic Editor: D. L. Jones

Copyright © 2012 Sandra C. K. Carlsen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

White clover is frequently used as a leguminous cover crop, serving as green manure, and is also included with grasses in cattle feed mixtures. Numerous biological effects reported for clover cultivation have been attributed to the production of bioactive secondary metabolites. Thus far the presence in soil of bioactive secondary metabolites from clover has received limited attention. In this paper we examine for the first time the release of flavonoids both from field-grown white clover and from soil-incorporated white clover plants of flavonoids, as analyzed by LC-MS/MS. The dominant flavonoid aglycones were formononetin, medicarpin, and kaempferol. Soil-incorporated white clover plants generated high concentrations of the glycosides kaempferol-Rha-Xyl-Gal and quercetin-Xyl-Gal. Substantial amounts of kaempferol persisted in the soil for days while the other compounds were degraded faster. These compounds should be considered in future studies of soil fatigue, allelopathic activity, and possible environmental risks from extended clover cultivation.