Comparing apples and apples; evaluating the impact of conventional and organic management on the soil microbial communities of apple orchards

Abstract

Ecological intensification of food production systems is gaining interest globally. Such processes seek to better support ecosystem services and improve soil health with approaches that have a stronger consideration for biological processes. Here, we investigated the effect of ecological intensification on soil health in an apple orchard context. To do this, we compared soil physicochemical properties and microbial diversity and composition across conventional orchards, organic orchards, and spatially paired remnant native ecosystem sites. Minimal differences in physicochemical properties were found between the conventional and organic orchards; however, microbial communities were distinct from each other. Organic management had no impact on either bacterial or fungal alpha diversity or heterogeneity but did increase dung saprotroph abundance. Soil physicochemical and microbial analysis revealed that orchards and native sites were significantly different, with orchards having significantly higher bacterial diversity and fungal heterogeneity. We found that soil physicochemical characteristics and microbial community parameters varied inconsistently between organic and conventional orchards. This variability is likely the result of legacy effects from historical land practices or inherent variation in management, irrespective of conventional or organic labels. In conclusion, apple orchard management was associated with distinct microbial communities and fungal trait abundance which may be indicative of alternate nutrient cycling and energy pathways. The similarities between organic and conventional apple orchard management highlight the necessity for a nuanced approach that identifies and promotes beneficial strategies for sustainable soil and agroecosystem management. We suggest that future research focus on individual practices/combination of practices of ecological intensification, rather than the broad farm classification (i.e. conventional vs organic).