Ray R. Weil is an internationally recognized expert on soil science, nutrient cycling, soil organic matter and cover crop systems for soil health and water quality. His methods for soil microbial biomass and active Carbon are adopted by USDA/NRCS and researchers worldwide. His research on multi-purpose cover crops and ecological approaches to soil management is used by landscape managers and farms, large and small. He has advised on food security and soil management in Africa and other developing regions. He teaches undergraduate and graduate-level courses in soil science, soil fertility and sustainable agriculture. His textbook, The Nature and Properties of Soils, is the most widely used soils textbook in the US and around the world.