Invited paper The role of livestock in enhancing agricultural systems: insights from mixed crop-livestock models

Abstract

Global food production faces mounting climate and health pressures, creating demand for agricultural systems that regenerate soils, recycle nutrients, improve human diets, reduce emissions, and minimize chemical inputs while maintaining farmer livelihoods. Integrated crop–livestock systems (ICLS), extensively researched in Brazil, offer a viable pathway to meet these combined challenges. This communication highlights evidence from long-term experiments and comparative studies showing how ICLS improve resource efficiency and food supply. We synthesize findings from multi-year field experiments and simulation studies that evaluate grazing management, soil nutrient cycling, carbon dynamics, and human-edible nutrient outputs under contrasting hydroclimatic conditions. Grazing animals provide functional synergies in ICLS by recycling nutrients through feces and urine, modifying soil structure via hooves, and enhancing soil–microbiota connectivity. Well-managed grazing increases soil carbon by up to 20% in mixed systems, improves nitrogen use efficiency, and decreases fertilizer dependence. Evidence from soybean–livestock rotations show energy and protein yields for human consumption rising by 24–28% compared to ungrazed systems, while diversified rice–livestock systems reduce unsustainability indexes and increase renewability by more than 120%. Nutritional yield analyses demonstrate that moderate grazing intensities buffer energy, protein, and micronutrient supply against drought stress, outperforming pure crop systems in both productivity and stability. ICLS simultaneously generate plant and animal foods from the same land, enhancing food quantity, nutritional diversity, and resilience while preserving arable soils. For farmers, ICLS diversifies income, reduces chemical costs, and strengthens adaptive capacity. Rooted in Brazilian innovation, these results demonstrate that livestock integration is essential to sustainable intensification and agricultural adaptation to climate variability today and in the future.