title: Contrasting temperature responses of dissolved organic carbon and phenols leached from soils.
abstract: OBJECTIVE
  Plant-derived phenols are a major input to the terrestrial carbon cycle that might be expected to contribute substantially to dissolved organic carbon (DOC) losses from soils. This study investigated changes in DOC and phenols in leachates from soil treated with individual plant litter types under seasonal temperature change.
  
  
  METHODS
  Senescing grass, buttercup, ash and oak litters were applied to soil lysimeters. Leachates were collected over 22 months and analysed for DOC and phenols. Phenols in litter and DOC were analysed using on-line thermally assisted hydrolysis and methylation with tetramethylammonium hydroxide (TMAH).
  
  
  RESULTS
  Mass loss differed between litter type (buttercup>ash>grass>oak). Phenol concentrations in the senescing litters (<2 % TOC) were small, resulting in minor losses to water. Seasonal soil temperature positively correlated with DOC loss from litter-free soils. An initial correlation between temperature change and total phenol concentration in grass and ash litter treatment leachates diminished with time. Dissolved phenol variety in all litter-amended soil leachates increased with time.
  
  
  CONCLUSIONS
  Plant-derived phenols from senescing litter made a minor contribution to DOC loss from soils. The strength of the relationship between seasonal temperature change and phenol type and abundance in DOC changed with time and was influenced by litter type.
authors.affiliation: School of Civil Engineering and Geosciences, Drummond Building, Newcastle University, Newcastle-upon-Tyne, NE1 7RU UK ; Department of Sustainable Soils and Grassland Systems, Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB UK.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Williams
authors.affiliation: Department of Sustainable Soils and Grassland Systems, Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB UK.
authors.forename: Jennifer A J
authors.initials: JA
authors.lastname: Dungait
authors.affiliation: Institute of Bio- and Geosciences, IBG-3: Agrosphere, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Bol
authors.affiliation: School of Civil Engineering and Geosciences, Drummond Building, Newcastle University, Newcastle-upon-Tyne, NE1 7RU UK.
authors.forename: Geoffrey D
authors.initials: GD
authors.lastname: Abbott
keywords: Dissolved organic carbon; Grassland soil; Leaf litter; Phenols; Seasonal temperature