Assessing the impact of land conversion to urban use on soils with different productivity levels in the USA

There has been increased public concern in the USA over the longterm impact of urbanization on the available land used to produce food, feed, and fiber, Concern that urban use of highly productive soils may threaten our food security and sustainability has been debated for nearly three decades. This study was primarily initiated to compare different soil productivity classes in terms of areas and proportion of land converted to urban uses in the USA. The methodology consisted of analyzing data resulting from a geographic information system (GIS) overlay of urban land use maps derived from the Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) nighttime imagery and layers of potential soil productivity. Soil productivity distributions were obtained using the Soil Rating for Plant Growth (SRPG) model based primarily on soil and landscape parameters contained in the State Soil Geographic (STAT-SGO) database, Currently, the urban land use covers approximate to3% of the conterminous USA and is primarily on areas that were originally of low and moderate soil productivity. Only 6% of the total land under urbanization had consisted of highly productive soils. However, land with highly productive soils, roughly 3% of the total U,S, area, has a higher level of urbanization (5%) than that of any other soil productivity category. States differ in the areas and proportion of land converted to urban uses in each soil productivity class. These results are a first step in determining the current status of soil resources in relation to urbanization and should be interpreted according to the scale and resolution of data sources and assumptions made in the soil productivity modeling.