PHOSPHORUS MOVEMENT IN THE SOIL AND ITS F ORM OF APPLICATION ON TOMATO CROP

A laboratory experiment was carried out iu order to study phosphorus m ovement in the soil profile with application of 150 and 300 kg/ha of P 2O5 in soil columms, in five different soils of the submedio Sao Franc isco river basin, Northeast Brazil. A field experiment was also carrie d out in 1989 in a sandy Red Yellow Latosol containing 1,7 ppm of avai lable P (Mehlich) to evaluate the effect of different levels and metho ds of phosphorus application on industrial tomato crop. The levels wer e, 60, 120, 180 and 240 Kg/ha of P2O5 applied in two different ways: t otally before planting, and 50% before planting and the other 50% appl ied 30 days after planting. A control treatment consisting of no phosp horus application was also included. The laboratory study showed that the leaching of phosphorus was up to 4-6 cm and 6-8 cm deep, in the so il with the highest clay content, respectively, for application of 150 and 300 Kg/ha of P2O5 Leaching was to the deepest layer (14-16 cm) in the soil with the lowest clay content, for both application levels. I n the field experiment, a positive response of the tomato crop to phos phorus application was observed. The maximum expected yield of 69,4, v ha was obtained with 189 Kg/ha of P2O5 The divided applied phosphorus gave a mean yield higher than that obtained from the single applicatio n.