Distribution and properties of sandy soils in the conterminous USA – A conceptual thickness model, and taxonomic analysis

Abstract

Sandy soils, as a group of soils, are unique soils. They have a specific set of physical and chemical soil properties that include rapid infiltration and conductivity, susceptibility to drought and erosion by wind, and low ability to hold water and nutrients. Sandy soils have a sandy or loamy sand texture in the fine-earth (<2 mm) fraction. They occur extensively in Florida, Nebraska, Michigan, Texas, Georgia, Wisconsin, and Minnesota. We present a conceptual thickness model for sandy soils with four depth classes: 1. soils that are sandy throughout the upper 100 cm, 2. soils that contain a sandy layer that is 50 cm or more thick over a finer-textured layer, 3. soils that have a fine-textured layer 50 cm or less over a sandy layer, and 4. soils that are sandy throughout but that are underlain by bedrock at a depth of 50 cm or less. These four classes include 2054 soil series covering nearly 600,000 km2 or 8% of the conterminous USA. There is a wide range of parent materials, but most sandy soils are formed in aeolian, marine, and outwash deposits and sandy soils occur mainly in dunes and coastal and outwash plains. Nearly three-quarters of the sandy soil area are over 100 cm deep. Sandy soils are contained primarily in the Entisol order (48% of soils on area basis), followed by Spodosols (15%) and Ultisols (13%). Nearly two-thirds of sandy soils occur in nine great groups, including Ustipsamments (12%), Torripsamments (10%), Udipsamments (7%), Quartzipsamments (7%), Haplorthods (6%), Alaquods (6%), Paleudults (5%), Kandiudults (4%), and Psammaquents (3%). As nearly half are Entisols, only 24% of the sandy soils have a diagnostic subsurface horizon. Argillic and spodic horizons occur in 18% and 13% of the soils, respectively. There is concern regarding climate change and erosion of beaches, particularly in Florida and California, the influence of sand mining on flooding in Texas, and the impact of sand mining on dunes in Michigan.