A possible trade-off between soil nitrogen availability and root carbon inputs to soil | Un possible compromis entre la disponibilité de l'azote dans le sol et les entrées de carbone des racines vers le sol
2019
Rees, Frédéric | Chenu, Claire | Andrieu, Bruno | Ecologie fonctionnelle et écotoxicologie des agroécosystèmes (ECOSYS) ; Institut National de la Recherche Agronomique (INRA)-AgroParisTech | INRA ; Université de Poitiers
International audience
Show more [+] Less [-]English. The potential of agricultural soils to store carbon (C) has been claimed to require a large amount of nitrogen (N) and therefore a high soil N availability. This assumption is based on the observation that stable soil organic compounds are characterized by a narrow range in C:N ratios. However, N-fertilizer additions have also been shown to increase respiratory C losses from soils. Furthermore, most of the organic C naturally stored in soils originate from plant C inputs, which occur both by aerial litter deposition and by root turnover and rhizodeposition. Root C inputs have been shown to contribute 2-3 times more to soil C sequestration than shoot-derived C inputs. However, root C inputs may be limited or even decrease when soil N availability increases beyond a certain level. A trade-off may therefore exist between the amount of soil available N and the potential of soil C sequestration associated to the inputs of root C. The existence of such trade-off and its possible consequences for the optimization of soil C sequestration will be discussed according to evidences from scientific literature and to a modelling approach describing how root C inputs to soil can evolve with soil N availability.
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