CARACTERISTIQUES MINERALOGIQUES ET CHIMIQUES DE QUELQUES SOLS SABLEUX DU QUEBEC EN REGARD DE LEUR EVOLUTION PEDOLOGIQUE

Abstract

A, B and C horizons of 13 sandy soil series were sampled in the lowlands of southern Quebec. From the amounts of pyrophosphate-extractable Fe and Al and clay contents, nine of these profiles were classified as Podzolic soils while the others were Brunisols. Formation of montmorillonite and dissolution of chlorite in Ae horizons indicate intense weathering of the minerals at this level. In the B horizons, vermiculite that was present in the parent material or resulted from the alteration of illite was often chloritized. Values of pH measured in 1 M NaF were generally higher than 10.2 for the B horizons. The amounts of phosphorus retained by the samples varied in the following ranges: 23–397 μg P/g of soil for A horizons, 301–1578 μg P/g of soil for B horizons and 71–296 μg P/g of soil for C horizons. Cation exchange capacity of the soils was lower than 10 meq/100 g of soil, except in those horizons that contained high amounts of organic matter and where values up to 27.6 meq/100 g were measured. Using regression equations, values were obtained for the CEC of the organic matter and the clay fraction of these sandy soils.