Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Plant and Soil 381-397 Carbon flows Microbial biomass Microbial exchanges Model proposition Agro-ecology Global change 2016 fdi:010066212 ENG Plant and Soil 0032-079X ISI:000368550700029 1-2 10.1007/s11104-015-2665-4 https://www.documentation.ird.fr/hor/fdi:010066212 https://www.documentation.ird.fr/intranet/publi/2016/03/010066212.pdf 398 Horizon (IRD) This study evaluated a framework for modelling the continuous exchange of carbon (C) between the atmosphere, plants, humus, and microorganisms, proposing a plant C model coupled to MOMOS, an existing microbial C model. C data were collected on low fertility cereal-legume cropping systems. Plant C and microbial C were modelled simultaneously and the growth parameters of plants and nitrogen-fixing microorganisms were fitted to the data. All C exchanges were successfully predicted using the same weather correction for plant and microbial processes. Most of the photosynthetic production was allocated to the roots, reducing yields. The C losses were found modelled mainly by root respiration for cereals, probably as an energy source for nutrient explorings, and by root mortality for legumes as a growth source for decomposers and symbiotic nodules. The effect of root-nodule activity on shoot growth was found non-linear. The system was modelled as a sink of 4.2 Mg C ha(-1) year(-1) in the soil's labile C reserve. This paper coordinates theoretical bases for modelling the processes regulating plant productivity associated with plant C losses. The tool appears to be robust and is now available for calculating the essential parameters of agro-ecology and climate change. 074 ; 020 ; 076 ; 082 UR210 Tunisie