title: The contentious nature of soil organic matter.
abstract: The exchange of nutrients, energy and carbon between soil organic matter, the soil environment, aquatic systems and the atmosphere is important for agricultural productivity, water quality and climate. Long-standing theory suggests that soil organic matter is composed of inherently stable and chemically unique compounds. Here we argue that the available evidence does not support the formation of large-molecular-size and persistent 'humic substances' in soils. Instead, soil organic matter is a continuum of progressively decomposing organic compounds. We discuss implications of this view of the nature of soil organic matter for aquatic health, soil carbon-climate interactions and land management.
authors.affiliation: Soil and Crop Sciences, School of Integrated Plant Sciences, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA.|Atkinson Center for a Sustainable Future, Cornell University, Ithaca, New York, USA.
authors.forename: Johannes
authors.initials: J
authors.lastname: Lehmann
authors.affiliation: Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, USA.|Institut für Bodenlandschaftsforschung, Leibniz Zentrum für Agrarlandschaftsforschung (ZALF), Müncheberg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Kleber
mesh_terms: D000383:Agriculture; D057486:Carbon Cycle; D018556:Crops, Agricultural / Q000378:metabolism; D017753:Ecosystem; D006812:Humic Substances / Q000032:analysis*; D012987:Soil / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D006812:Humic Substances; D012987:Soil; D014867:Water