Ecologically based agriculture benefits earthworms in Argentina’s large-scale systems: farm-level strategies matter

Conventional agriculture expansion and intensification are among the main causes of land degradation and soil biodiversity losses worldwide. Developing more sustainable approaches poses major challenges in large-scale agriculture, as it is the case in the Argentine Pampas, one of the largest agricultural regions in the world. Among soil biota, earthworms regulate soil organic matter dynamics, soil structure formation and maintenance, and create a habitat for numerous organisms, making them especially useful for assessing agricultural performance in terms of preserving soil biological processes. However, earthworm communities in ecologically based agricultural systems have been seldom studied in the region, and the role of farm-scale factors in shaping these communities remains even less understood. Thus, our aims were (1) to assess the effect of three different systems: large-scale ecologically based agriculture, large-scale conventional agriculture, and natural grasslands, on earthworm community attributes and composition; and (2) to understand which variables at the farm scale, related to management strategies and to regional and soil conditions, mostly shape earthworm communities in agricultural soils. We sampled earthworms in 54 sites representing the three systems. We characterized farms in terms of management practices and regional and soil conditions. We observed that ecologically based agriculture increased earthworm abundance, biomass and richness compared to conventional agriculture. However, geographic location played a more significant role in determining species identity than the system. Decreasing crop proportion and increasing non-cropped areas at the farm scale were the most important management practices positively affecting earthworms. This is one of the few studies in the Argentine Pampas to show that ecologically based, large-scale agriculture effectively benefits earthworm communities, and the first to identify how farm-scale factors influence them—particularly mixed farming and the maintenance of non-cropped areas within farms. We believe these findings offer strong encouragement for large-scale farmers to adopt more sustainable practices.