title: Earthworms change the quantity and composition of dissolved organic carbon and reduce greenhouse gas emissions during composting.
abstract: Dissolved organic carbon (DOC) has recently been proposed as an indicator of compost stability. We assessed the earthworms' effect on DOC content and composition during composting, and linked compost stability to greenhouse gas emissions and feeding ratio. Earthworms reduced total DOC content, indicating larger stability of vermicompost than of thermophilic compost. The concentrations of humic acid and fulvic acid were reduced by earthworms, whereas there was no significant effect on hydrophobic neutrals and hydrophilics. The humic acid fraction was depleted more quickly than the other compounds, indicating humic acid degradation during composting. The optimum feeding ratio decreased DOC content compared to the high feeding ratio. The lowest N2O emissions were also observed at the optimum feeding ratio. Our study confirmed the use of DOC content and composition as an indicator of compost stability and suggested that feeding ratio should be considered when assessing the earthworms' effect on stabilisation and greenhouse gas emissions.
authors.affiliation: Department of Soil Quality, Wageningen University and Research, PO Box 47, 6700 AA Wageningen, The Netherlands; Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark; Department of Natural Resource Management, Jimma University, Ethiopia. Electronic address: nigatu@plen.ku.dk.
authors.forename: Abebe
authors.initials: A
authors.lastname: Nigussie
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
authors.forename: Sander
authors.initials: S
authors.lastname: Bruun
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
authors.forename: Andreas
authors.initials: A
authors.lastname: de Neergaard
authors.affiliation: Department of Soil Quality, Wageningen University and Research, PO Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Kuyper
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000517:prevention & control* / Q000706:statistics & numerical data; D000818:Animals; D001578:Benzopyrans; D001673:Biodegradation, Environmental; D006812:Humic Substances; D008372:Manure; D009835:Oligochaeta / Q000502:physiology*; D012037:Refuse Disposal / Q000379:methods*; D012987:Soil
chemical_list: D000393:Air Pollutants; D001578:Benzopyrans; D006812:Humic Substances; D008372:Manure; D012987:Soil; C005023:fulvic acid
keywords: Dendrobaena veneta; Eisenia fetida; Feeding ratio; Nitrous oxide; Vermicomposting