EXTRATORES PARA FÓSFORO DISPONÍVEL EM LATOSSOLOS E EFICIÊNCIA DE FONTES FOSFATADAS PARA MILHO CULTIVADO EM VASO

Abstract

The test was performed at the Centro Universitário de Patos de Minas, MG, Brazil, with maizeplants in soil samples classified as Typic loam (LAM), clayey Oxisol (LVarg) and very clayey Oxisol (LVmarg). Theexperimental design was a 3 x 5 factorial with DBC, soils and P sources and control, respectively, in four blocks.The treatments consisted of applying mineral sources of P + control (no P application): triple superphosphate, rockphosphate Gafsa, Araxá rock phosphate and silicate termofosfato. The cultures were grown in pots of 3 dm3 of soil,maintaining four plants per pot for 35 days after emergence. At the end the plants were collected, separated into rootsand shoots and the contents of P were analyzed. Concentrations of available-P, extracted by Mehlich-1 and RTA, weredetermined for each pot. The available-P by Mehlich-1 showed a low ratio for extractable P in soils where sources oflow solubility were applied, while the determined by RTA showed greater similarity with the P content present in planttissues. For the cultivation in the clayey Oxisol the application of termofosfato presented greater agronomic efficiencyin relation to triple superphosphate.

Keywords

• Determination of phosphorus
• agronomic efficiency index
• phosphorus source
• soils.