During 1975 and the spring of 1976, N requirements were determined for irrigated ‘Walter’ tomatoes (Lycopersicon esculentum Mill.) growing on Troup loamy sand with and without polyethylene mulch. Maximum soil moisture deviation occurred in the unmulched plots in the zone of illuviation to depths of 60 to 75 cm. Moisture ranged from 3 to 15% with the maximum recorded after vines were killed by frost. Highest N concentration (15.8 ppm NO3-N) occurred in mulched plots at a depth of 15 cm; whereas the highest concentration (11.5 ppm NO3-N) in unmulched plots occurred at 45 cm. The highest yield of 29.8 MT/ha was produced with 60 kg/ha N on mulched plots. The highest yield without mulch (25.6 MT/ha) required 138 kg/ha of N.