Can potato cropping be made regenerative? Cover crops and dead organic mulch support soil microbial activity

To address the decline in soil organic matter and thus soil life and soil health due to intensive tillage in organic potato production, innovative regenerative farming approaches employ cover crops and transferred dead organic mulch to improve plant nutrition, minimize soil disturbance, and foster soil microbial activity. Starting in 2019 to 2021, three organic two-year field experiments were set up in a field that had been converted to non-inversion tillage since 2015, to investigate the effects of cover cropping before and organic dead mulch application to potatoes compared to weedy fallow and N-fertilization with hair meal pellets as controls. For every experiment, microbial biomass carbon (MBC), basal respiration, and fungal ergosterol were examined, starting with the cover crop in fall before potatoes until the spring in the crop succeeding potatoes. In all three experiments, initial effects on soil microbial activity depended on the incorporated biomass with no differences between vetch-triticale as a cover crop or a weedy fallow. During potato cropping, however, especially the incorporation of the vetch-triticale cover crop combined with the application of grass-clover mulch resulted in increased MBC, basal respiration and ergosterol. After potato cropping, basal respiration and ergosterol were increased in plots with weedy fallow before and mulched with grass-clover during potatoes pointing to a slower and overall more fungal based mulch degradation at that time in those plots. These results underscore the potential of regenerative practices to enhance soil microbiology during potato cultivation.