Prairie strips quickly alter soil bacterial and fungal communities in strips, but not in surrounding cropland

Abstract

The conversion of tallgrass prairie to row crop agriculture in the U.S. Midwest has reduced soil biodiversity and ecosystem functions. Prairie strips are zones of perennial vegetation integrated into row crop farm fields that increase native plant, insect, and wildlife diversity in agricultural landscapes, and may also enrich belowground diversity of soil bacteria and fungi. Within a 35 year old cropping system experiment, we introduced prairie strips in two treatments - one with reduced chemical inputs and one with no chemical inputs – and we measured soil microbial communities every year for the first four years of prairie strip establishment, hypothesizing that communities would shift in soils under prairies, and subsequent dispersal from prairie communities would alter composition in surrounding cropland. We assessed alpha diversity, beta diversity, and relative abundance of prairie-associated microbial phyla in prairie strip soils and in cropland soils at multiple distances from prairie strips. We found that as early as two months after planting, prairie strip bacterial and fungal communities diverged from cropland community composition, exhibited higher diversity than cropland, and were enriched in microbial phyla characteristic of remnant tallgrass prairie soils. Prairie strips harbored different communities in the two cropping systems, indicating that land use history shapes communities early in prairie strip establishment. Microbial communities in surrounding croplands were not altered by the presence of prairie strips, neither on average nor as a function of distance. We show that prairie strips restore tallgrass prairie soil biota in multiple cropping systems, but prairie taxa are not likely to spill over into low intensity cropland soils due to cropland management practices that inhibit microbial dispersal and establishment.