Factors that interfere with phosphorus fixation: I - incubation period

Abstract

Research material for this work was soil samples from the plow layer from five soils. Samples were taken and submitted to different incubations periods (T0 = 0; T1 = 2; T2 = 20 and T3 = 200 hours) after treatment with a monocalcium phosphate solution (4 ml of a solution with 1,500 ppm P per 10 grams of soil). Of the soils used nos. I, II and V were Latosols; whereas the others were Podzolics (Soils III and IV). At the end of each incubation period, the phosphorus content was determined using the extraction solution of 0.025 N H2SO4 and 0.05 N HCl. The quantity of fixed phosphorus was calculated by subtracting the values found for T1, T2 and T3 from the "corrected strata" for T0. For this purpose each soil sample was treated with an equal amount of destilled water and was observed at the four time periods specified above. In accordance with the statistical analysis (Tukey's test) it was found that for each soil had a statistical significance at the level of 1% as related to the linear and quadratic effects of the incubation period. A joint analysis of the 5 soils samples Tukey's test at the 5% level showed the lack of marked differences among Soils I, II and V (Latosols), but Soils of III and IV nos. (Podzolics) showed a statistical difference.