CHEMICAL AND CLAY MINERALOGICAL PROPERTIES OF ORTSTEIN SOILS FROM THE MARITIME PROVINCES

Abstract

The two poorly drained ortstein horizons contained very low amounts (< 0.2%) of Na-pyrophosphate-extractable Fe. The considerably higher values of extractable Al and the fact that clods of ortstein horizons slaked in Na-pyrophosphate suggested that Al-organic complexes might be the major cementing agent, especially in the upper B horizons of the poorly drained pedons. Iron probably contributed significantly to the cementation of other ortstein samples. In the ortstein soils of the Nova Scotia site, minerals in the sola of well drained soils differed markedly from those in poorly drained soils. Vermiculite, apparently derived from mica or chlorite, was the dominant phyllosilicate in the clay fraction of well drained sola but it was not detected in the poorly drained sola. However, in the New Brunswick site, there is little difference in the clay minerals in well and poorly drained soils. Smectite was the dominant silicate clay in Ae horizons; vermiculite was dominant in the B horizons; and mica and chlorite were dominant in the C horizons. Many of the clay samples, especially in the B horizons of the well drained soils, appeared to be amorphous to X-ray. However, treatment with dilute hot NaOH usually greatly enhanced the X-ray diffraction patterns. Scanning electron microscope pictures and the 020 peaks of phyllosilicates in X-ray diffractions patterns indicate that the apparent increase in crystallinity is due mainly to better alignment of the clay particles.