Substantial and accelerated soil health improvement with conversion from conventional to regenerative practices
Interest in promoting soil health is growing among practitioners and researchers. However, the speed and degree to which a shift in management can achieve change remains unclear. We measured soil organic matter, water stable aggregates, nutrient availabilities, and microbial biomass (fatty acid analyses) and composition (molecular methods) within a working farm zero, five and nine years after conversion from conventional to regenerative management. We found substantial and consistent increases in soil organic matter, water stable aggregates and microbial biomass (all important indicators of soil health) in an avocado orchard, citrus orchard, a pasture, and vegetable garden, with the greatest increases during the first five years. Nutrient availabilities, on the other hand, differed among crops but showed no consistent change. Fungal and bacterial communities shifted, but not fungal: bacterial biomass ratios. The abundance of arbuscular mycorrhizal fungi increased in all crops except the vegetable garden, possibly due to very high soil phosphorus availability there. Fungal taxa likely to be saprotrophs increased in both abundance and richness across crops, whereas putative fungal pathogen abundance and richness tended to decrease, possibly indicating enhanced disease suppression in soils. Overall, we found substantial and rapid shifts in physical, chemical, and biological properties of soils consistent with an improvement in soil health following the transition from regular applications of inorganic fertilizers and pesticides to cover cropping, compost additions, and rotational grazing.