Isotope evidence for soil organic carbon pools with distinct turnover rates—II. Humic substances

Eric Lichtfouse (1) , Sen Dou , Sabine Houot (2) , Enrique Barriuso (2)

1 ASD - Agronomy for Sustainable Development
2 EGC - Environnement et Grandes Cultures

Two experiments using 13C-enriched substrates have been undertaken to evaluate the relative turnover rates of the main pools of soil organic carbon namely bulk organic carbon, humin and humic acids. Firstly, soil organic matter was labelled naturally during a 5 year field experiment by cultivating Zea mays, a C4 plant, on a soil that had previously grown isotopically distincts C3 plants, e.g. wheat. Secondly, soil organic matter was labelled artificially with either Image-glucose of 13C-enriched Image-glucose during a 21 day laboratory experiment. Isotopic variations observed during both experiments demonstrated the existence of soil carbon pools of decreasing turnover rates: humic acids > bulk organic carbon > humin.

Mots clés: soil organic matter; humic acids; humin; 13C; glucose; wheat; maize; 14C

Domaines: Science des sols; Chimie analytique; Géochimie; Milieux et Changements globaux; Sciences agricoles

Eric Lichtfouse, Sen Dou, Sabine Houot, Enrique Barriuso. Isotope evidence for soil organic carbon pools with distinct turnover rates—II. Humic substances. Organic Geochemistry, 1995, 23 (9), pp.845-847. ⟨10.1016/0146-6380(95)80005-C⟩. ⟨hal-00192675⟩