Livestock management and compost addition shape soil microbial communities and enzymatic activities in Mediterranean agroecosystems
Discuss this preprint
Start a discussion What are Sciety discussions?Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Grazing modifies soils through trampling, nutrient redistribution, and changes in vegetation, while compost supplies organic matter and nutrients. Yet how these factors interact to shape soil microbial diversity, composition, and functioning remains unclear. We assessed bacterial, fungal, and arbuscular mycorrhizal (AMF) communities, together with soil enzymatic activities, under three livestock regimes (exclusion, equine, ovine) before and after compost addition in a Mediterranean olive orchard. Bacterial diversity showed no significant changes across treatments, whereas fungal and AMF diversity responded more strongly. Fungal richness differed among livestock regimes, with lowest values in exclusion plots, and both fungi and AMF declined following compost addition. These trends contrasted with the stability of bacterial richness, indicating taxon-specific sensitivity rather than uniform effects of grazing or compost. Livestock regime was the main driver of microbial composition (R² = 0.27–0.30), while compost induced significant but secondary shifts (R² ≈ 0.16–0.18). Interactive effects occurred in all microbial groups, and distinct bacterial, fungal, and AMF phylotypes characterized pre- and post-compost conditions. Compost promoted copiotrophic bacterial taxa and decomposer fungal classes. Enzymatic responses were divergent: urease decreased by 64%, glucosaminidase increased by 63%, and phosphatase declined two- to six-fold after compost addition. Grazing reduced β-glucosidase activity by 40–68%, and compost–livestock interactions shaped dehydrogenase and aminopeptidase patterns. Overall, organic inputs and herbivore identity jointly influence soil microbial assembly and nutrient cycling. These findings underscore the need to consider grazing context when evaluating compost as a strategy to enhance soil health in Mediterranean agroecosystems.
