We prove a de Rham-like theorem for foliated bundles F ! (M; F )¼ ! B showing that the cohomology H¤( F ) is isomorphicto the equivariant cohomology H¡ ³ eB; C1 (F); ¡ = ¼1 (B)and eB the universal covering of B. When B is an Eilenberg-Mac Lane space K (¡; 1) the cohomology H¤ ( F ) is the cohomology of the ¡-module C1 (F). This gives algebraic models for H¤ ( F ) and geometrial models for the cohomology of the ¡-module C1 (F). Using this isomorphism and a theorem of J. Palis and J.C. Yoccoz on the triviality of centralizers of diffeomorphisms, [14] and [15] we show that H¤( F ) is infinite dimensional for a large class of foliated bundles. Using this isomorphism R. u. Luz computed in [9] the cohomology of the foliated bunddles suspensions of actions of Z P by afine transformations of T Q. AMS (MOS) Subj class: 57R30

A acidez potencial tem grande importância pela sua utilização na determinação da saturação por bases e auxílio na recomendação da necessidade de calagem. Este estudo teve por objetivo avaliar a relação entre o teor de H + Al e o pH SMP, visando estabelecer uma equação para estimar a acidez potencial de solos da Região Norte de Minas Gerais. As análises dos teores de H + Al (acetato de cálcio 0,5 mol L-1 a pH 7,0) e dos valores de pH SMP foram realizadas no laboratório de fertilidade do solo da EPAMIG/CTNM em 50 amostras de solo, com valores de pH em água variando de 4,6 a 7,8, teores de carbono orgânico de 3 a 45 g kg-1 e os de argila de 80 a 610 g kg-1. A acidez potencial, expressa em cmol c dm-3, pode ser estimada pelo uso do pH SMP, utilizando para isso a seguinte equação: H + Al = 0,00359 + 1556,5806 e- pHSMP (R² = 0,96**).

Potential acidity is of great importance for the base saturation determination and for the recommendation of liming. The objective of this study was to evaluate the relationship between pH SMP and H + Al contents, in order to establish an equation for the potential acidity estimation of soils from Northern Minas Gerais, Brazil. The H + Al concentration (0.5 mol L-1 calcium acetate pH 7.0) and pH SMP were analysed at EPAMIG/CTNM soil fertility laboratory, in 50 soil samples. The pH in water of the soil samples ranged from 4.6 to 7.8, organic carbon contents varied from 3 to 45 g kg-1 and clay contents from 80 to 610 g kg-1. The potential acidity, expressed in cmol c dm-3, can be estimated by measuring the pH SMP using the following equation: H + Al = 0.00359 + 1556.5806 e- pH SMP (R² = 0.96**)