Management of Brachiaria ruziziensis biomass affects soybean productivity in integrated crop-livestock system

Abstract

The use of Brachiaria ruziziensis as a cover crop in integrated crop-livestock systems is consolidated, promoting changes in the structuring and protection of the soil surface, with greater nutrient cycling, resulting in increased grain yield. However, it is still necessary to investigate how different management practices of Brachiaria ruziziensis biomass during the off-season influence soybean productivity in succession. Therefore, the objective was to compare, over two years, the conventional method of soybean cultivation (without soil cover biomass) with different management practices of Brachiaria ruziziensis biomass (free growth, cut and regrowth of the forage, and grazing) during the off-season in a integrated crop-livestock system and how these management practices affect desiccation efficiency, biomass production and decomposition, C:N ratio, nutrient cycling, as well as soybean productivity in succession. The experiment was implemented in a Neossolo Quartzârenico in the state of Goiás, Brazil, using a randomized complete block design with four replications. Treatments consisted of soybean grown in Brachiaria ruziziensis biomass: with free growth; with cutting and regrowth of the forage; and under grazing during the off-season, in addition to an additional treatment of soybean without soil cover biomass. The results showed that the free growth management reduces the efficiency of forage desiccation. The grazing system, during the off-season, although providing lower biomass production of plant cover, maximizes nutrient recycling and fertilizer return to the soil, resulting in greater input cost savings. Soybean productivity in Brachiaria ruziziensis biomass in all systems increased by 23.49 % compared to soybean grown without soil cover biomass. The identification of forage management strategies provides pathways to improve nutrient use efficiency. These results can inform agricultural policies focused on sustainability, support decision-making in agricultural systems, and contribute to practices that maximize productivity and soil health, in addition to reducing costs with the acquisition of mineral fertilizers.