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.

从业者与科研人员对提升土壤健康的关注度与日俱增。然而，管理模式转型所能带来的土壤健康改善速度与程度，目前仍不明确。本研究在某商业化农场中，选取了从传统管理模式转为再生管理模式后的第0、5、9年的土壤样本，测定了土壤有机质、水稳性团聚体、养分有效性，以及微生物生物量（采用脂肪酸分析法）与微生物群落组成（采用分子生物学方法）。研究发现，在鳄梨园、柑橘园、牧场与菜园中，土壤有机质、水稳性团聚体及微生物生物量这三类核心土壤健康指标均出现了显著且持续的提升，且增幅在转换后的前五年最为明显。相较而言，养分有效性因作物种类而异，并未呈现出一致的变化趋势。真菌与细菌群落结构发生了显著改变，但真菌与细菌的生物量比值并未出现明显变化。除菜园外，所有种植系统中的丛枝菌根真菌（arbuscular mycorrhizal fungi）丰度均有所提升，这可能与菜园土壤极高的有效磷含量有关。各类种植系统中，潜在腐生真菌类群的丰度与物种丰富度均有所提升，而疑似真菌病原菌的丰度与丰富度则呈下降趋势，这或许意味着土壤的病害抑制能力得到了增强。总体而言，当农场从常规施用无机肥料与农药的模式，转变为覆盖种植、堆肥施加与轮牧的再生管理模式后，土壤的物理、化学与生物学特性均发生了显著且快速的变化，这与土壤健康水平的提升相一致。