Clay-sized soil minerals are known to protect organic carbon (OC) from mineralisation by formation of organo-mineral associations limiting its availability to microorganisms. The impact of soil fauna on these processes is poorly known. The aim of this study was to investigate the effect of earthworms on organic matter (OM) decomposition and association with minerals during a laboratory experiment. We used a model system consisting of fresh OM incubated with and without epigeic earthworms (Eisenia andrei and foetida) in presence of different types and amounts of phyllosilicates (kaolinite, montmorillonite) and an iron oxide (goethite) and combinations of these minerals. Our experimental setup included a high OM:mineral ratio to represent the soil-litter interphase. We monitored OC mineralisation during 196 days. Additionally, we investigated physicochemical parameters and chemical OM characteristics of decomposition products by determination of water-soluble OC (WSOC) and acquisition of solid-state ¹³C NMR spectra. We also analysed microscale organisation of the organo-mineral associations produced with and without earthworms by transmission electron microscopy (TEM).

Earthworms enhanced OC mineralisation in all treatments. They also led to greater reductions of OC emissions in the presence of minerals as compared to the mineral-free control, depending on the type and amount of minerals added. The presence of earthworms affected microbial biomass, the concentration of WSOC and increased the contribution of aromatic compounds to OM decomposition products. Microscale analyses by TEM showed that earthworms favoured association of minerals with partly degraded OM along with completely degraded material, while in absence of earthworms only completely degraded OM was associated with minerals. We conclude that earthworms impact OM decomposition through (1) their effect on microbial biomass and the physicochemical parameters of microbial habitat and (2) the formation of OM associations by changing the OM types associated to minerals and possibly by creating closer association of partly degraded OM and iron oxides. The stability of these associations remains to be investigated.

已知粘土大小的土壤矿物质会通过形成有机矿物质联合来限制有机碳（OC）的矿化作用，从而限制其对微生物的利用。土壤动物对这些过程的影响知之甚少。这项研究的目的是在实验室实验中研究worm对有机物（OM）分解以及与矿物质缔合的影响。我们使用了一个模型系统，该模型系统由新鲜的OM组成，该模型与有无表皮earth（Eisenia andrei和foetida）存在不同类型和数量的层状硅酸盐（高岭石，蒙脱石）和氧化铁（针铁矿）以及这些矿物的组合。我们的实验装置包括高OM：矿物质比，代表土壤-凋落物的中间相。我们监测了196天的OC矿化情况。此外，我们通过确定水溶性OC（WSOC）和获取固态¹³ C NMR光谱研究了分解产物的理化参数和化学OM特性。我们还通过透射电子显微镜（TEM）分析了有with和无without产生的有机-矿物缔合的微观组织。

all在所有处理中均会增强OC矿化作用。与不含矿物质的对照相比，它们还导致存在矿物质的情况下更多地减少了OC排放，具体取决于所添加矿物质的类型和数量。的存在影响了微生物的生物量，WSOC的浓度并增加了芳香族化合物对OM分解产物的贡献。TEM的微观分析表明，worm倾向于将矿物与部分降解的OM以及完全降解的物质结合起来，而在没有absence的情况下，只有完全降解的OM与矿物相关。我们得出结论，worm通过以下方式影响OM分解：（1）它们对微生物生物量和微生物生境的理化参数的影响；（2）通过改变与矿物相关的OM类型并可能通过建立部分降解的OM的更紧密的联系来形成OM和氧化铁。这些关联的稳定性仍有待研究。