Forms of inorganic phosphorus in carbonatic soils in the Pantanal of Mato Grosso do Sul, Brazil

The western region of the southern Pantanal is characterised by soils with high phosphorus (P) contents, derived from materials surrounding lithostratigraphic units, accumulated fluvial transport. However, studies on forms and availability P in these are scarce. objective this study was to evaluate different inorganic their relationship some attributes carbonatic Mato Grosso do Sul, Brazil. Hedley’s sequential fractionation scheme used soil profiles: Kastanozems (profiles P1 P3) Gleysol (profile P2). Total contents were similar three profiles, 3782–5637 mg kg–1, mean values 22% for organic 46% (P.i). P.i results indicated that profiles there a predominance following order: P-NaOH 0.5 mol L–1 > P-NaHCO3 0.1 P-HCl, is, adsorbed microaggregates, labile, oxides precipitated calcium (Ca), respectively. highest total verified surface horizons, correlation contents. Residual all representing 29.0–33.3% P, being correlated CaCO3 studied had labile fraction P.i-NaHCO3, possibly associated processes reduction iron during periods floods, making available. P.i-NaOH L–1, moderately oxides, showed few differences compared non-labile fractions Ca (P.i-HCl). Possibly, matter bound Ca, inhibiting formation precipitates available more fractions.