For soil heating the load demand is approximately 5 W/m2/°C (0.26 W/Sq. ft/°F). So to increase the temperature in the soil 15 degrees you would need 15 x 5 = 75 W/m² of installed power. For soil heating of sports arenas, the load is normally 60-90 W/m2 (4.5-6.5 W/sq. ft). In for example a football field, you will with soil heating, prolong the green season, keep the ground free of frost and melt snow and ice to some extent.