Pasture-crop rotations modulate the soil and rhizosphere microbiota and preserve soil structure supporting oat cultivation in the Pampa biome
Victoria Cerecetto, Carolina Leoni, Stephanie D. Jurburg, Ioannis D. Kampouris, Kornelia Smalla, Doreen Babin
Abstract
Mixed systems of grain and livestock production based on pasture-crop rotations are a promising strategy to promote agriculture resilience and allow an ecological intensification of agriculture yet little is known about underlying processes in soil. To test the hypothesis that pasture-crop rotations preserve soil structure and select for beneficial soil and rhizosphere microbiota, supporting soil health and grain production, a long-term field experiment under no-tillage was studied. The experiment evaluated a gradient of land use intensities and vegetation diversities, from highly intensive continuous cropping to the least intensive system i.e. a nearby natural grassland, with two intermediate land use intensities i.e. short pasture-crop rotation and long pasture-crop rotation. Soil health was assessed based on soil physicochemical properties, microbial (Bacteria/Archaea and Fungi) community diversity and composition and oat performance. Pasture-crop rotations preserved soil bulk density and larger aggregates better than continuous cropping. High-throughput amplicon sequencing of 16S rRNA gene and ITS fragments revealed that the pasture-crop rotations fostered taxa that are associated with soil structure maintenance and selected potential plant-beneficial bacterial genera in the oat rhizosphere (i.e. Bosea , Devosia and Microbacterium ), that may have contributed to the observed increase in N uptake, N accumulation and biomass in oat. In summary, this study shows that pasture-crop rotations are an ecologically sustainable alternative to continuous cropping in the Uruguayan Pampa biome. • Pasture-crop rotations preserved soil structure and yielded higher oat biomass. • Land use intensity affected soil and rhizosphere microbial communities. • Pasture-crop rotations enriched Devosia , Microbacterium , Bosea, Nitrososphaeraceae. • Duration and vegetation of pasture determined the extent of its soil legacy. • Pasture-crop rotations are a sustainable alternative to continuous cropping.