Pastures and Integrated Crop-Livestock Systems for Multiple Ecosystem Services.

Greater demands for agriculture to provide food, feed, fiber, and fuel place increased pressure on farmers to intensify their production practices. Increased use of external inputs and converting marginal land for cropping can compromise the ecosystem services obtained from agriculture, especially conservation, soil health, and biodiversity. An alternative is to develop conservation agricultural systems that exploit synergies of crop diversity to improve ecosystem services. Our working hypothesis is that highly diverse agricultural systems, especially those that integrate crops and livestock, will conserve natural resources, enhance ecosystem services, and generate economic and environmental sustainability while maintaining productivity. As outlined by Franzluebbers, conservation agricultural systems rely on three principles to enhance ecosystem services: 1) minimizing soil disturbance, 2) maximizing soil surface cover, and 3) stimulating biological activity. We suggest that diversity is the key concept that encompasses these three principles. In this paper, we explore the concept of diversity and its role in maximizing ecosystem services from managed grasslands and integrated agricultural systems (i.e., integrated crop-livestock systems). We also examine tradeoffs involved in realizing greater ecosystem services. Previous research has shown improvements in herbage productivity with increased forage diversity but little response in terms of animal production, which suggests significant tradeoffs. Fulfilling the multiple ecosystem functions needed to maintain a healthy pasture and grazing will entail a multi-scale approach with different forages and combinations of forage species distributed across a farm according to site suitability and the goals of the producer. The concept of dynamic cropping systems incorporates a long-term strategy of annual crop sequencing that optimizes crop and soil use options to attain production, economic, and resource conservation goals by using sound ecological management principles. Integrating dynamic cropping systems with livestock production increases the complexity of management but also creates synergies among the system components that improve resilience and sustainability.