BIOAVAILABILITY OF PHOSPHORUS ON HIGHLY WEATHERED OXISOILS OF THE BRAZILIAN MID-WEST

Soils from mid-west Brazil show strong phosphorus (P) fixation, which can reduce the efficiency of P fertilizers. Under this condition, soil competes with the plant for the applied P adsorbing it strongly in its mineral fraction. Nevertheless, in areas where crops are grown and fertilizers are added for many years, soil fertility status has increased over time, making these soils nonresponsive to P. The objective of this study was to evaluate how P availability changes with soil use. Forty soil samples were collected under different types of land use: native forest, pasture, no-tillage, and areas with periodic tillage. P fractionation was performed to determine the amount of P in the organic and inorganic fractions with high, medium, and low lability under each land use. Corn was cultivated in a greenhouse experiment to evaluate P uptake and values correlated with different P fractions. The results showed differences in the P fraction relations among different land uses. Cultivated areas (no tillage and periodic tillage) accumulated greater amounts of P in all fractions than pastures and the native forest. A higher proportion of labile organic P was observed under no tillage than under periodic tillage. NaHCO3 and NaOH 0.1 mol L-1were the most relevant P fractions for shoot P uptake. No tillage promoted the accumulation of available P fractions, suggesting that it is a good management strategy to ensure fertilizer use efficiency Made available in DSpace on 2022-01-11T16:00:35Z (GMT). No. of bitstreams: 1 Bioavailability-of-phosphorus-on-highly-weathered-Oxisoils-2021.pdf: 585048 bytes, checksum: f63367d92d52df0fa301f18aeddea44b (MD5) Previous issue date: 2021