Food systems face major challenges with the convergence of global climate, water, and energy crises. At the same time, the industrialization of agriculture threatens key ecosystem processes on which food production depends. In this talk, I will integrate insights from research conducted in the U.S. and Brazil to discuss how an ecological approach to managing crop diversity can simultaneously enhance ecological and social functions of agroecosystems, and increase resilience to global change. In terms of ecological functions, I focus on managing legume nitrogen (N) fixation to build soil organic carbon (SOC) stocks and improve soil N retention. For instance, in an experiment on 10 farms spanning a gradient of SOC levels, I found that hairy vetch (a legume cover crop) downregulated N-fixation rates with increasing N availability in intra-aggregate particulate organic matter, and with increasing N mineralization rates, suggesting a mechanism for internal N cycling efficiency with legume N sources. Our smaller-scale laboratory and field studies suggest that increasing predictive understanding of the continuous and plastic nature of plant functional traits could inform how to optimize management of crop diversity for multiple benefits, particularly for cover crop mixtures. In terms of social and health outcomes, a survey with 75 family farmers showed how Brazil’s flagship public food procurement policy, Zero Hunger, has increased the diversity of edible crops and livestock, farm household autonomy, and household gender equality. Finally, I share findings from farmer interviews to discuss key barriers and opportunities to agroecosystem diversification.

Jennifer Blesh is an agroecologist and Associate Professor in the School for Environment and Sustainability and the Sustainable Food Systems Initiative at the University of Michigan. She received her PhD in Soil and Crop Sciences from Cornell University. Prior to her current appointment, she was an NSF postdoctoral fellow at the Federal University of Mato Grosso in Brazil. Jennifer conducts ecological and interdisciplinary research to identify the environmental, agricultural, and social outcomes of diverse types of farming systems. Her work focuses on increasing crop diversity, including identifying how cover crops and perennials affect soil health and nutrient cycling processes, especially legume nitrogen fixation. She also studies social processes that lead to food system transformation and resilience.