MORE THAN 60 PERCENT of the 2.3 billion acres of land in the United Statesis in private ownership. Of this acreage, approximately 20 percent (442 million acres) is in cropland and 26 percent (587 million acres) is in permanent grassland pasture and range (Lubowski et al. 2006).The farms and ranches are managed by less than 2 percent of the population (Vesterby and Krupa 2001).The management of cropland soils not only influences food and fiber production but can also have a major impact on the quality of U.S. air and water, including such seemingly remote resources as shellfish beds in marine estuaries and global climate conditions. Thus, whether the current use of these agricultural soils is sustainable in the long run is worthy of close examination.