title: Evaluation of dissolved organic carbon as a soil quality indicator in national monitoring schemes.
abstract: BACKGROUND
  Monitoring the properties of dissolved organic carbon (DOC) in soil water is frequently used to evaluate changes in soil quality and to explain shifts in freshwater ecosystem functioning.
  
  
  METHODS
  Using >700 individual soils (0-15 cm) collected from a 209,331 km(2) area we evaluated the relationship between soil classification (7 major soil types) or vegetation cover (8 dominant classes, e.g. cropland, grassland, forest) and the absorbance properties (254 and 400 nm), DOC quantity and quality (SUVA, total soluble phenolics) of soil water.
  
  
  RESULTS
  Overall, a good correlation (r(2)= 0.58) was apparent between soil water absorbance and DOC concentration across the diverse range of soil types tested. In contrast, both DOC and the absorbance properties of soil water provided a poor predictor of SUVA or soluble phenolics which we used as a measure of humic substance concentration. Significant overlap in the measured ranges for UV absorbance, DOC, phenolic content and especially SUVA of soil water were apparent between the 8 vegetation and 7 soil classes. A number of significant differences, however, were apparent within these populations with total soluble phenolics giving the greatest statistical separation between both soil and vegetation groups.
  
  
  CONCLUSIONS
  We conclude that the quality of DOC rather than its quantity provides a more useful measure of soil quality in large scale surveys.
authors.affiliation: School of the Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, United Kingdom.
authors.forename: David L
authors.initials: DL
authors.lastname: Jones
authors.affiliation: School of the Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Simfukwe
authors.affiliation: School of the Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, United Kingdom.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Hill
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Lausanne, Switzerland.
authors.forename: Robert T E
authors.initials: RT
authors.lastname: Mills
authors.affiliation: Centre for Ecology and Hydrology, Environment Centre Wales, Bangor, Gwynedd, United Kingdom.
authors.forename: Bridget A
authors.initials: BA
authors.lastname: Emmett
mesh_terms: D002244:Carbon / Q000032:analysis*; D017753:Ecosystem; D004784:Environmental Monitoring; D005618:Fresh Water / Q000032:analysis*; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; D002244:Carbon