Litter decomposition is positively related to soil fauna species richness especially in livestock-integrated agricultural fields

Abstract

Litter decomposition is vital for the maintenance of soil health and long-term sustainability of agricultural landscapes. Soil macro- and mesofauna facilitate decomposition and nutrient cycling ensuring nutrient availability for microbes and plants. Yet, how agricultural land-use intensity and environmental conditions influence the contribution of fauna to the process of litter decomposition remains poorly understood. To address this knowledge gap, a litter decomposition study was conducted in annual crops under conservation, conventional, and livestock-integrated agricultural management, with undisturbed natural grasslands as reference sites. Within each site, four pairs of litterbags of two mesh sizes containing fresh leaves of perennial Lolium perenne were used to allow (coarse mesh) and exclude (fine mesh) macro-and mesofauna effects on decomposition. The litterbags were collected at monthly intervals for a period of four months and analysed for fauna diversity and decomposition rates. The highest decomposition estimates were recorded within the integrated and conservation farming sites, and this was attributed to favourable habitat conditions, which supported a balance of diverse functional fauna communities. Litter mass loss was higher in the presence of soil fauna within the coarse mesh litterbags compared to fine mesh where fauna was excluded. Litter mass loss was not significantly associated with arthropod diversity or abundance but was strongly linked to arthropod species richness. The contributions of fauna to decomposition were affected by temperature, soil moisture and land-use intensity. These results highlight that less intensively managed and diversified agricultural systems maintain functional biodiversity which drive the process of litter decomposition and therefore nutrient cycling.