Phosphorus collectors made from filter paper and synthetic cloth, were tested to evaluate their feasibility of determining the need for phosphate application. The collectors were coated with two types of oxides, iron oxide and aluminium oxide. The capacity of the collectors was tested by placing them in a 2 mL of solution containing phosphorus (PO4(3-)) in the concentration of 0.0, 1.00, 3.00, 5.00, 7.00, 9.00 and 11.00 µ g.mL-1, respectively, after which they were placed in contact with four types of soil (LBa, LRd, LEd and Ca) and incubed for 0.0 and 24 h. In this test the soils were kept at a humidity equivalent to 150 mmHg suction. The amount of phosphorus extracted from the solutions was tested at intervals between 0,0 and 11.0 µ g of phosphorus/mL. Results indicated that collectors were most efficient in Dystrophic Dark-Red Latosol (LEd) and less efficient in "Bruno álico" Latosol (LBa) and Cambisol (Ca). Synthetic cloth was the support yielding the best performance, whereas iron oxide lining was the most adequate lining material. Phosphorus collection increased with time of incubation.
phosphorus; phosphorus availability; phosphorus diffusion; phosphorus extraction
