Positive effects of regenerative organic agriculture on soil biology

This is the authors' abstract. We don't add key points for this paper.

Despite growing interest in regenerative organic agriculture (ROA), no well-replicated field experiment has simultaneously quantified the effects of multiple ROA practices on soil microbial, earthworm, and arthropod communities. The combined net effect of ROA practices (crop rotations, cover cropping, organic fertilization, minimum soil disturbance etc.) on key soil biological indicators has rarely been quantified. Here we use a plot-scale randomized block-design experiment to assess how multiple ROA practices have influenced the (1) composition of the soil microbial community, (2) abundance of earthworms, and (3) abundance and diversity of the soil arthropod community. We found that ROA had overall positive effects on soil biology. Phospholipid Fatty Acid (PLFA) and Neutral Lipid Fatty Acid (NFLA) analyses show how, over only two years since the introduction of ROA practices, the soil microbial community shifted towards an increasing abundance of fungal markers and in particular a significant increase of the 16:1ω5 biomarker for arbuscular mycorrhizal (AM) fungi. On the other side, soil bacterial groups that are generally considered to be more copiotrophic (which grow and reproduce rapidly in nutrient-rich environments), including Actinobacteria, increased in relative abundance in the conventional soils receiving synthetic nutrient fertilization. We also observed a significant increase in the number of earthworms in the ROA-managed soil. Number of earthworms in regenerative organic soils varied between 103 and 249 m −2 whereas in the conventional soils, the number of earthworms varied between 0 and 4 m −2 . We found that the total number of soil arthropods significantly increased in the regeneratively organic managed soils. The number of euedaphic arthropods adapted to life in the soil was higher in the regenerative organic soils as well as the number of epiedaphic generalist organisms, not strictly tied to the soil environment. The regenerative organic soils showed greater species richness, a more even distribution of species, and a more complex community structure than conventional soils, which receive synthetic fertilizer, pesticide and herbicide inputs, and are subject to greater soil disturbance. The increasing abundance of AM fungi and earthworms and the greater arthropod diversity observed in our regenerative organic soils strongly suggest that ROA may contribute to soil biological conditions that are associated with long-term sustainability and resilience. Many farmers and policymakers are reluctant to adopt regenerative organic practices partly because perceived benefits may take decades to materialize. Our findings within 2–3 years provides encouraging evidence that soil health benefits can accrue relatively quickly, potentially lowering perceived barriers to adoption.