Effect of grain crop-pasture rotations on bacterial and archaeal communities in a grain-pasture system in Uruguay

A better understanding of soil and plant-associated microbiomes in agroecosystems holds the potential to increase agricultural sustainability. We hypothesized that crop-pasture rotation improves grain production by maintaining soil health and fostering microbial diversity and plant-beneficial microorganisms. In a grain cropping system with no-tillage, continuous cropping (CC), short (SR) and long (LR) crop-pasture rotation (two and four years of pasture with cattle grazing, respectively) and an adjacent native grassland (NG, reference of a healthy soil) were compared in terms of soil health. We assessed soil health based on various physicochemical and biological properties. Soil aggregate distribution, soil bulk density and crop yields in SR/LR were improved compared to CC. In spring, the soil and rhizosphere microbial (Bacteria and Archaea) communities were shaped by the rotation. Resulting in an increase of the relative abundance of e.g. Bacillus and Xanthobacteraceae in SR/LR soils. In summary, our results suggest that crop-pasture rotations have the potential to maintain soil health and crop production better than CC when compared to NG.

深入认识农业生态系统中的土壤及植物相关微生物组（microbiome），有望提升农业可持续性。本研究提出假设：粮-草轮作可通过维持土壤健康、促进微生物多样性与植物有益微生物群落，提升粮食产量。本研究在免耕粮食种植体系中设置四组处理：连作（CC）、短期（SR）与长期（LR）粮-草轮作（分别为放牧肉牛2年、4年的草地），以及邻近的原生草原（NG，健康土壤参照），对比各组的土壤健康状况。本研究基于多项理化与生物学特性对土壤健康进行评估。相较于连作组，短期与长期轮作组的土壤团聚体分布、土壤容重及作物产量均得到改善。春季时，轮作模式塑造了土壤与根际微生物（细菌（Bacteria）与古菌（Archaea））群落结构，进而提升了短期、长期轮作土壤中例如芽孢杆菌属（Bacillus）与黄色杆菌科（Xanthobacteraceae）的相对丰度。综上，本研究结果表明，相较于健康土壤参照原生草原（NG），粮-草轮作模式相比连作更能维持土壤健康与作物生产能力。