Soil organisms are essential for the functioning of agrosystems, especially in the process of litter decomposition. Litterbags constitute one common way to assess litter decomposition and to investigate the role of the different groups of soil organisms in the decay activity. However, there is currently no standardized litterbag protocol to measure the effects of soil organisms on litter decomposition. Furthermore, litterbag studies remain scarce in agrosystems and little information is available about the influence of different groups of soil organisms depending on agricultural practices. The development of cropping systems that rely on high soil biodiversity and fertility however requires a detailed understanding of these processes. In order to address this need and to have an overview of the existing protocols, we conducted a review on litterbag experiments in annually cropped soils. We collected information on the experimental design (e.g. duration, number of replicates), litterbags (e.g. size, mesh), climate, soil type, standing crop, enclosed litter (e.g. litter type, quality) and methods used to characterize organic matter decomposition and soil organisms. The effects of soil organisms of different size classes (meso- and macrofauna) was assessed with a meta-analysis performed on studies using litterbags of different mesh sizes. The general effect size of soil macrofauna, mesofauna (in addition to soil microorganisms) and of their combination was assessed with a three-level random-effect model accounting for the random effect at the study level. This effect was compared for subgroups based on climate, soil, standing crop, agricultural system and litter type as categorical factors, and for depth of bags, duration of the experiment and size of litter pieces as continuous factors. Macrofauna, mesofauna and the combination of both were found to significantly increase litter decomposition. Surprisingly, meso- and macrofauna contributed equally to litter decomposition and their effects were not additive (when comparing the role of meso- and macrofauna independently and simultaneously). These effects tend to be influenced by various factors: climate, soil, standing crop and agricultural system for macrofauna; standing crop and litter type for mesofauna; and soil, standing crop and litter type for their combined effects. Multi-mesh litterbag experiments showed that even in soils with high disturbances, soil organisms of several size classes have a significant impact on organic matter decomposition. While this study showed that both soil macrofauna and mesofauna increased litter decomposition in annual cropping systems, there are still numerous gaps in our knowledge of the impacts of the agronomic (e.g. cropping system, practices, crop type) and environmental contexts (e.g. climates, soils). Forecasting future studies, we provide guidelines to develop a standard litterbag protocol adapted to the specificities of annually cropped soils.

土壤生物对于农业系统的功能至关重要，尤其是在凋落物分解过程中。垃圾袋是评估垃圾分解和研究不同土壤生物群在腐烂活动中的作用的一种常用方法。然而，目前没有标准化的垃圾袋协议来衡量土壤生物对垃圾分解的影响。此外，在农业系统中，垃圾袋研究仍然很少，而且关于不同类型土壤生物根据农业实践的影响的信息也很少。然而，依赖高土壤生物多样性和肥力的种植系统的发展需要对这些过程有详细的了解。为了满足这一需求并概述现有协议，我们对每年种植的土壤中的垃圾袋实验进行了审查。我们收集了有关实验设计（例如持续时间、重复次数）、垃圾袋（例如大小、网眼）、气候、土壤类型、立茬作物、封闭垫料（例如垫料类型、质量）以及用于表征有机物质分解和土壤生物。通过对使用不同网孔大小的垃圾袋的研究进行的荟萃分析，评估了不同大小类别（中型和大型动物）的土壤生物的影响。土壤大型动物群、中型动物群（除土壤微生物外）及其组合的一般效应大小通过考虑研究水平随机效应的三级随机效应模型进行评估。根据气候、土壤、立茬作物、农业系统和垫料类型作为分类因素，袋深度、试验持续时间和垫料块大小作为连续因素。发现大型动物、中型动物和两者的结合会显着增加垃圾分解。令人惊讶的是，中型和大型动物对凋落物分解的贡献相同，并且它们的影响不是相加的（在独立和同时比较中型和大型动物的作用时）。这些影响往往受到多种因素的影响：气候、土壤、常备作物和大型动物的农业系统；中型动物的立茬作物和垫料类型；和土壤、立茬作物和凋落物类型的综合影响。多网格垃圾袋实验表明，即使在扰动较大的土壤中，几个大小等级的土壤生物对有机物质分解有重大影响。虽然这项研究表明土壤大型动物群和中型动物群都增加了一年生作物系统中的凋落物分解，但我们对农艺（例如种植系统、做法、作物类型）和环境背景（例如气候、土壤）的影响的认识仍然存在许多差距）。预测未来的研究，我们提供了制定一个标准的垃圾袋协议的指南，以适应每年种植的土壤的特性。土壤）。预测未来的研究，我们提供了制定一个标准的垃圾袋协议的指南，以适应每年种植的土壤的特性。土壤）。预测未来的研究，我们提供了制定一个标准的垃圾袋协议的指南，以适应每年种植的土壤的特性。