Vain A. C. auteur aut IRD Rakotondrazafy N. auteur aut IRD Razanamalala K. auteur aut IRD Trap Jean auteur aut IRD Marsden C. auteur aut IRD Blanchart Eric auteur aut IRD Bernard Laetitia auteur aut IRD text journalArticle eng text/pdf born digital access A positive Priming Effect (PE) is defined as an acceleration of the decomposition of soil organic matter (SOM) by a fresh organic matter (FOM) input. But in the literature many studies present this phenomenon as an extra loss of carbon from SOM to the atmosphere. SOM is actually a mixture of pools with different turnover rates, and microorganisms generating PE are heterotrophic. Therefore, whether PE is in fact an extra loss of C depends on the targeted SOM pool (high or low turnover) and the ratio between the incorporation of the primed carbon into microbial biomass vs its mineralization. A13 nutrient-poor tropical soil (enriched or not with a cocktail of nutrients) was incubated and submitted to two successive wheat-straw inputs with differential 13C enrichment, in order to observe the PE of one straw on the other, and to measure the specific respiration of the different carbon pools. In our nutrient-poor soil, nutrient enrichment intensified soil basal respiration while it lowered straw mineralization. Our study showed that, fresh and primed C allocation between microbial biomass and CO2 were similar and depended on the nutrient status of the soil. We did not observe any impact of freshly amended C on the fate of the previous amendment, but conversely we observed an impact of the previous organic input on the decomposition rate of the following one, as well as the allocation of the liberated C toward biomass rather than CO2. specialized Soil organic matter Fresh organic matter Priming effect Microbial biomass Specific respiration MADAGASCAR IMERINTSIATOSIKA 068 074 105 103332 [8 p.] 2021 1164-5563 https://www.documentation.ird.fr/hor/fdi:010082550 10.1016/j.ejsobi.2021.103332 1164-5563 [F B010082550] https://www.documentation.ird.fr/hor/fdi:010082550 https://www.documentation.ird.fr/intranet/publi/2021-09/010082550.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2021-09-17 2025-02-24 fdi:010082550 fre