Pastureland intensification and diversification in Brazil mediate soil bacterial community structure changes and soil C accumulation

Conventional pasture management has been responsible for diffuse soil degradationin tropical pastures. However, sustainable management practices can be used to improve soil health. We tested the effect of adopting intensive and diversified pasture management systems, i.e., fertilized pasture (FP), integrated crop-livestock (ICL) and integrated livestock-forest (ILF), in comparison to conventional pasture management (CS) in Brazil. The treatments were located under contrasting climate conditions (tropical humid, tropical mesic and subtropical) and soil types (Oxisol and Ultisol). The conversion time from CS to FP, ICL and ILF ranged from 6, 3-15 and 3 years, respectively. We focus on management effects on soil chemical and biochemical properties and their interactions with the soil bacterial community structure and soil C accumulation. The results showed that pasture intensification and diversification in sites previously managed under CS, increased by 82% the soil chemical properties related to soil fertility and shifted the soil bacterial community structure. The soil biochemical properties such as microbial biomass C, geochemical P and the enzymes beta-glucosidase and acid phosphatase were the most sensitive in the conversion of CS to FP, ICL and ILF. The structural equation modeling suggested that for FP, ICL and ILF there was a positive impact of soil bacterial community structure and mainly soil chemical properties on soil C accumulation. Results in the present study provided useful knowledge for the best understanding of soil-management-microbe interactions, and provide more insights into the controlling factors of soil C accumulation during management system changes in pastures sites in Brazil.

Automated summary

The study demonstrated that intensive and diversified pasture management systems can improve soil health by enhancing soil chemical and biochemical properties, as well as influencing the soil bacterial community structure.