BEHAVIOR OF CHELATING-AGENTS AS EXTRACTAN TS OF MICROELEMENTS IN SANDY SOILS

The present paper describes the behaviour of three chelating agents wi th phosphonic groups (piperidine methylene phosphonic acid: xy-2-oxo-4 -(beta-hydroxyethyl)-1.4.2-oxaza-phospha (V)-cyclohexane: OAPMP) as ex tractans of microelements in sandy soils. The studies were carried out using different concentrations of complexing agent at various pH valu es in the range 5.0 - 9.0. The Cu, Zn, Mn and Fe extracted were determ ined by Atomic Absorption Spectrophotometry. The sequestrant ability o f the acids increases with the amount of heteroatoms in the hexacyclic ring, this effect is highly marked for Fe. The complexation is in the order OAPMP > MMP > PMP.