The feasibility of using soil warming for utilization and dissipation of reject heat from power plants was demonstrated in a year-long test operation of a field prototype in Pennsylvania. A parallel network of 5-mm-diam polyethylene pipes was buried at a 0.3-m depth and with 0.6-m spacing in the soil covering a 15- × 60-m area to convey hot water simulating condenser cooling water from a power plant. Crop response to the heated soil varied: Snap beans and warm season forage crops such as sudangrass responded with increased yields, while cool season forage crops experienced decreased yields. Winter wheat yields were also increased, but winter barley was winter-killed due to delayed development of cold tolerance in the warm soil. Heat dissipation from the buried pipes was primarily by thermal conduction to the soil surface. Rates of heat loss from the buried pipes were most accurately predicted using an equation that included an explicit term for heat conduction below the pipes. Estimated soil warming land area necessary to dissipate all the reject heat from a 33% efficiency, 1500-MW electrical power plant based on minimum measured summer heat loss rates was 76 km2 compared to the economic optimum of 18.2 km2 determined as the least-cost system.