The effects of the application of pure grade CaF2 and CaCO3 on the concentration of Al and other chemical elements in the percolated solution of acid soil samples, collected over an eight month period, were evaluated in a greenhouse experiment in Piracicaba county, State of São Paulo, Brazil. The pH values increased in the percolated solution of soil samples that received both CaCO3 and CaF2. The CaF2 treatments were more efficient than CaCO3 treatments on the withdrawal of Al from […]

Hematites from nine soils and one from itabirite rock were concentrated with 5 mol L-1 NaOH, and analyzed by XRD (step scanning 0.02o2θ/20 s), to determine the unit cell parameters. The samples were dissolved by extraction with DCB to determine the Fe (Fed) and Al (Ald) content. Al substitution was estimated from a0 using established regressions currently in use based on hematites synthesized at 25°C (Al25) and 70°C (Al70). The a0 values ranged from 0.50380 to 0.50200 nm, corresponding to […]

Gypsum is an amendment used to alleviate subsoil acidity. However, there are doubts about its use for acid soils that previously received applications of lime and fertilizers. There are also doubts on the use of gypsum in the cases of the use of high liming rates or for aluminum tolerant crop varieties. This paper describes a limestone and gypsum experiment conducted from 1987 to 1992 at the Tatui Experimental Station, State of São Paulo, Brazil. The experiment was on a […]