Impact of diversification and intensification of crop rotation (DICR) in soil bacterial microbiota in on-farm study after four and seven years

No-till agricultural diversification and intensification of crop rotations (DICR) effects on soil biological properties were studied in an on-farm study. DICR stands for increasing soil cultivation period and consequent reduction of fallow times by using different winter and summer crops, including cover crops, in two and three-year rotation schemes. Five different levels of DICR were tested -typical local rotation, intermediate rotation, high intensification with grasses, high intensification with legumes, and a continuous multispecies pasture-, and replicated at three different agricultural farms situated in the Argentinean Pampa. The soils were analyzed at four and seven years after DICR started. The on-farm studies were established at each site in a plot of ca. fifty hectares with a typical local rotation history and evaluated after four and seven years of changes. The impact on prokaryotic soil communities was measured by 16S rRNA gene sequencing. Overall, the sustained DICR showed a progressive effect with reduced Bray-Curtis dissimilarities at second sampling. At the phylum level, Actinobacteria, Bacteroidetes, Verrucomicrobia, BCR1, and WS3 increased with the level of DICR while Acidobacteria, Firmicutes, Gemmatimonadetes, OD1, and TM7 showed the opposite trend. Selected taxa based on LEfSe detection were associated with typical historical rotation after the four years and pasture after the seven years, expressing the cumulative effect of DICR. Bacterial communities' structures were associated with plant stubble and crop yield. Understanding how more sustainable practices such as DICR shift the soil microbiota can assist in designing agricultural systems that increase soil health, C sequestration, and crop yield.