Phosphorus movement in the soil and its form of application on tomato crop

Abstract

A laboratory experiment was carried out in order to study phosphorus movement in the soil profile with application of 150 and 300 kg/ha of P₂O₅ in soil columms, in five different soils of the submédio São Francisco river basin, Northeast Brazil. A field experiment was also carried out in 1989 in a sandy Red Yellow Latosol containing 1,7 ppm of available P (Mehlich) to evaluate the effect of different levels and methods of phosphorus application on industrial tomato crop. The levels were, 60, 120, 180 and 240 Kg/ha of P₂O₅ applied in two different ways: totally before planting, and 50% before planting and the other 50% applied 30 days after planting. A control treatment consisting of no phosphorus 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 soil 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. In the field experiment, a positive response of the tomato crop to phosphorus application was observed. The maximum expected yield of 69,4 t/ha was obtained with 189 Kg/ha of P₂O₅. The divided applied phosphorus gave a mean yield higher than that obtained from the single application.