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.

正启动效应 (PE) 被定义为新鲜有机质 (FOM) 输入加速土壤有机质 (SOM) 的分解。但在文献中，许多研究将这种现象描述为从 SOM 到大气的额外碳损失。SOM实际上是不同周转率的池的混合物，产生PE的微生物是异养的。因此，PE是否事实上C的额外损耗取决于目标SOM池（高或低营业额）并进入微生物生物质的涂底漆的碳的结合之间的比率VS其矿化。培育了一种¹³营养贫乏的热带土壤（富含或不含有混合营养素），并提交给两个连续的小麦秸秆输入，差异为¹³C富集，以观察一根稻草在另一根稻草上的PE，并测量不同碳库的比呼吸。在我们营养贫乏的土壤中，营养丰富会加强土壤基础呼吸，同时降低秸秆矿化。我们的研究表明，微生物生物量和 CO ₂之间的新鲜和引发 C 分配相似，并且取决于土壤的养分状况。我们没有观察到新修正的 C 对前一修正的命运有任何影响，但相反，我们观察到先前有机输入对后一修正分解率的影响，以及释放的 C 分配给生物量而不是比 CO ₂。