Source, level and time of nitrogen fertilization on the yield of industrial tomato

Abstract

In two experiments, one in 1981 and the other one in 1984, with the tomato crop (Lycopersicon esculentum Mill) under irrigation in a Red Yellow Latosol of the medium São Francisco Valley, was evaluated the effect of source, levels and time of application of nitrogen on the yield of this crop. The source of N were urea and ammoniun sulphate. In the first experiment the levels were: 0, 50, 100 and 150 kg/ha of N, applied as the follows: a) the total N at the planting; b) 50% at the planting time and 50% 30 days after; c) one third at planting time, one third 25 days after and the rest 50 days after. In the second experiment, 0, 40, 80,120 and 160 kg/ha of N were tested, 1/3 at planting and 2/3 30 days after. There was no significant difference between the source, neither among the time of application of N. Concerning the levels in the first experiment, the optimum economic level was 100 kg/ha of N which produced 28 t/ha of commercial fruits. For the second experiment this economic level was 97 kg/ha of N and the yield corresponded to 67 t/ha of commercial fruits. These yields were 111% and 50% higher than those obtained in the check treatments without N for the first and second experiments, respectively.