Land‐Use Change Enhances Organic Phosphorus Pools in Oxisols in Brazil's New Agricultural Frontier

Land‐use types and management systems can affect the availability of phosphorus (P) by modifying its compartments. The aim of this study was to evaluate the organic and inorganic fractions of P in an Oxisol in the Cerrado region of Brazil, considering various land‐use types and management systems and the period of application. Nine different land‐use types and management systems were evaluated in the district of Uruçuí, in the Cerrado region of the state of Piauí: no‐tillage (NT 3 and NT 6 , under cultivation for 3 and 6 years, respectively), pasture (PA 2 and PA 6 , under cultivation for 2 and 6 years, respectively), eucalyptus (EU 6 and EU 12 , under cultivation for 6 and 12 years), conventional tillage (CT 2 and CT 8 , under cultivation for 2 and 8 years) and native Cerrado (NV), representing a balanced system. Sequential P fractionation was carried out on soils collected at depths of 0–0.1, 0.1–0.2, 0.2–0.3 and 0.3–0.4 m, resulting in organic and inorganic P fractions of different availability (Hedley sequential fractionation). Across most systems and depths, organic P (Po) predominated over inorganic P (Pi), especially in the labile and moderately labile pools. Pasture systems (PA 2 and PA 6 ) showed the highest levels of biological P, reaching 762 mg dm −3 in PA 6 , with biological P representing 82% and 85% (average of both PA 2 and PA 6 ) of the labile and moderately labile P pools, respectively. No‐tillage and eucalyptus systems also accumulated significant Po in moderately labile fractions, indicating that conservationist systems promote long‐term P stabilisation. Conversely, conventional tillage reduced total and recalcitrant P pools, highlighting its unsustainable nature. These findings suggest that land management practices promoting organic matter inputs and nutrient cycling enhance P retention and efficiency, contributing to sustainable agriculture in the MATOPIBA region.