Below-ground biodiversity in organic agroforestry with free-range pigs in Denmark

Summary

Integrating biodiversity into agricultural systems, particularly through agroforestry, is increasingly recognized as an important step to achieve sustainable land management and soil health. Free-range farming, where animals are allowed to interact directly with their environment, may add benefits to soil ecosystems. In this study, we investigated how free-range pig farming, combined with agroforestry elements, influences belowground biodiversity, including microbial communities comprising both bacterial and fungal parts and invertebrate communities. Prokaryotic, fungal, and invertebrate diversity were assessed using environmental DNA (eDNA), while earthworm density was measured via conventional method of hand sorting to obtain abundance measures. Soil samples were collected from two organic pig farms with differing agroforestry tree compositions and different periods with pigs in the fields. Our results showed that higher soil microbial biodiversity was associated with the presence of pigs, suggesting that free-range pig systems integrated with agroforestry practices can enhance soil ecological complexity. In addition, the tree age and species composition significantly impacted the soil microbial and invertebrate community composition. Earthworm abundance was generally negatively affected by the pig production system, and our results indicate that periods of undisturbed grass-clover cover, without pig activity, had a positive effect on the earthworm community.