About 35 million acres not being cultivated have high potential for crop use and 117 million more have medium potential, according to the 1982 National Resources Inventory (NRI) conducted by the U.S. Department of Agriculture. USDA committees evaluated the economic potential for converting land based on physical characteristics of the soil; size and location of land parcels; type of effort required for conversion; and commodity prices, production costs, and land conversion costs for 1981. High potential land required evidence that similar land had been converted to crop use during 1979-82; medium potential land did not. Converted high potential land would increase cropland area by 8 percent over the 421 million cropland acres inventoried in 1982. The cropland base would increase 36 percent if both high and medium potential land were converted, but soil erosion could increase by just over 1 billion tons annually, nearly 20 percent above 1982. If only high potential lands were converted, the erosion increase could be only about 4 percent. Less favorable cost/price relationships for crop production since 1982, several provisions in the 1985 farm act, and change in the U.S. tax code will all tend to discourage conversions. (Author/KC)