Technical Abstract: The National Program structure of USDA-ARS provides an opportunity to coordinate research on problems of national and global significance. A team of USDA-ARS scientists is conducting nationally coordinated research to develop predictions of manure N availability to protect water quality and improve farm solvency. Experimental design and research protocols were developed and used in common across all participating locations. Laboratory incubations are conducted at each location with a minimum of 3 soils, 3 temperatures, 2 wetting/drying regimes, and 2 manure treatments. A soil from the central U.S. (Catlin silt loam, fine-silty, mixed, superactive, mesic Oxyaquic Arguidoll) is used as an internal reference across all locations. Incubation data are compiled across locations to develop generalized predictions of manure N mineralization (Nmin). Field validation data are then obtained by monitoring N transformations in manure-amended soil cores equipped with anion exchange resin to capture leached nitrate. This field data will be used to compare laboratory based predictions with field observations of Nmin in each soil, climatic zone, and manure type represented. A Decision Support System will then be developed for predicting manure N mineralization across ranges in soil, climate, and manure composition. This research is expected to promote optimal N use efficiency in manure amended soils, thereby maximizing economic benefits and minimizing deleterious environmental consequences of manure application to cropland.