Metam sodium fumigation in potato production systems has varying effects on soil health indicators

Sustainable agriculture requires soil management practices that increase productivity while minimizing detrimental impacts on soil health. Soil fumigation is a common practice which controls soil-borne diseases and promotes yield, but can potentially influence soil health by suppressing soil microorganisms. Considering the wide use of fumigation, we still lack a complete understanding of its effects on soil health, which prevents us from understanding the resilience of agricultural ecosystems and prescribing management activities accordingly. Moreover, soils are highly variable, and so both the agronomic benefits and any negative impacts of fumigation on soil health may vary across soil types. In this study, we investigated the impact of metam sodium fumigation on a variety of soil health indicators using the potato fields of Wisconsin, USA. We collected soil and potatoes from 7 commercial potato fields subjected to fumigation and non-fumigation treatments, representing two distinct growing regions. We measured the effect of fumigation on tuber yield and soil-borne diseases, soil chemistry, microbial activities and community structure. Fumigated plots showed higher potato yield as well as bacterial diversity and microbial-mediated carbon retention than unfumigated plots in central sandy soils; the opposite trend was observed in northern loamy soils. We also found that soil bacterial community diversity was closely associated with yield responses to fumigation. We concluded that fumigation has varying effects on selected soil health indicators depending on the soil conditions. Sustainability of soil health is largely dependent on the soil microbiome, as negative feedback may be more likely to happen where microbial diversity is sensitive to fungicide application.