title: Simulating urban waste compost effects on carbon and nitrogen dynamics using a biochemical index.
abstract: Composting has emerged as a valuable route for the disposal of urban waste, with the prospect of applying composts on arable fields as organic amendments. Proper management of urban waste composts (UWCs) requires a capacity to predict their effects on carbon and nitrogen dynamics in the field, an issue in which simulation models are expected to play a prominent role. However, the parameterization of soil organic amendments within such models generally requires laboratory incubation data. Here, we evaluated the benefit of using a biochemical index based on Van Soest organic matter fractions to parameterize a deterministic model of soil C and N dynamics, NCSOIL, as compared with a standard alternative based on laboratory incubation data. The data included C mineralization and inorganic N dynamics in samples of a silt loam soil (Typic Hapludalf) mixed with various types of UWC and farmyard manure. NCSOIL successfully predicted the various nitrogen mineralization-immobilization patterns observed, but underestimated CO(2) release by 10 to 30% with the less stable amendments. The parameterization based on the biochemical index achieved a prediction error significantly larger than the standard parameterization in only 10% of the tested cases, and provided an acceptable fit to experimental data. The decomposition rates and C to N ratios of compost organic matter varied chiefly according to the type of waste processed. However, 62 to 66% of their variance could be explained by the biochemical index. We thus suggest using the latter to parameterize organic amendments in C and N models as a substitute for time-consuming laboratory incubations.
authors.affiliation: Environment and Arable Crops Research Unit, Institut National de la Recherche Agronomique, 78850 Thiverval-Grignon, France. Benoit.Gabrielle@grignon.inra.fr
authors.forename: Benoît
authors.initials: B
authors.lastname: Gabrielle
authors.forename: Jeanne
authors.initials: J
authors.lastname: Da-Silveira
authors.forename: Sabine
authors.initials: S
authors.lastname: Houot
authors.forename: Cédric
authors.initials: C
authors.lastname: Francou
mesh_terms: D001673:Biodegradation, Environmental; D002244:Carbon / Q000032:analysis / Q000378:metabolism*; D002947:Cities; D003247:Conservation of Natural Resources; D005308:Fertilizers; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D012037:Refuse Disposal / Q000379:methods*; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D005308:Fertilizers; D012989:Soil Pollutants; D002244:Carbon; D009584:Nitrogen