Integrated crop–livestock systems: Strategies to achieve synergy between agricultural production and environmental quality

• Diversity in agriculture systems drives the productivity-environment trade-off.
• Grasslands couple C–N cycles and reduce environmental fluxes.
• Crop–livestock integration diversifies landscape mosaics enhancing biodiversity.
• Crop–livestock systems should provide both high productivity and ecosystem services.

A need to increase agricultural production across the world for food security appears to be at odds with the urgency to reduce agriculture's negative environmental impacts. We suggest that a cause of this dichotomy is loss of diversity within agricultural systems at field, farm and landscape scales. To increase diversity, local integration of cropping with livestock systems is suggested, which would allow (i) better regulation of biogeochemical cycles and decreased environmental fluxes to the atmosphere and hydrosphere through spatial and temporal interactions among different land-use systems; (ii) a more diversified and structured landscape mosaic that would favor diverse habitats and trophic networks; and (iii) greater flexibility of the whole system to cope with potential socio-economic and climate change induced hazards and crises. The fundamental role of grasslands on the reduction of environmental fluxes to the atmosphere and hydrosphere operates through the coupling of C and N cycles within vegetation, soil organic matter and soil microbial biomass. Therefore, close association of grassland systems with cropping systems should help mitigate negative environmental impacts resulting from intensification of cropping systems and improve the quality of grasslands through periodic renovations. However, much research is needed on designing appropriate spatial and temporal interactions between these systems using contemporary technologies to achieve the greatest benefits in different agro-ecological regions. We postulate that development of modern integrated crop–livestock systems to increase food production at farm and regional levels could be achieved, while improving many ecosystem services. Integrated crop–livestock systems, therefore, could be a key form of ecological intensification needed for achieving future food security and environmental sustainability.