ABSTRACT Low availability of phosphorus (P) is a constraint to agricultural development in tropical soils, owing to the high fixation of P in the soil matrix. Land-use change can modify soil P dynamics. This study aimed to evaluate the effects of land-use change on P fractions in a Ferralsol under different systems of use and management. Inorganic (Pi) and organic soil P (Po) fractions were assessed by sequential fractionation using H2O, NaHCO3, NaOH, hot concentrated HCl and H2SO4-H2O2 as extractants. The systems in the study were as follows: pasture (PAST), no-tillage system (NT), organic cultivation (ORG) with 2, 6, 8 and 10 years of organic management, and conventional continuous cropping tillage (CT). A native Cerrado forest (F) area was used as reference. In general, Po forms predominated over Pi, with exception of the CT soil, where Pi represented 41% of the total P. On average, conversion of F into the CT system reduced levels of Po in the soil by up to 72%. The soil P resilience index showed that P inputs in the CT and NT systems were insufficient at recovering P availability after the land-use change. On the other hand, the most recent ORG systems demonstrated the greatest efficiency at restoring the equilibrium of the soil P state. The hypothesis that less intensive agricultural systems increase the soil labile P pool, enhancing available P levels, was confirmed. Agricultural systems that used organic inputs and reduced soil disturbance were found to be more efficient at recovering and maintaining soil P availability.
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