MINERALOGICAL COMPOSITION OF 3 CULTIVATED SWEDISH SOILS

Two clay fractions and one silt fraction from the Ap horizon of three cultivated Swedish soils, the Kjettslinge sandy loam, the Fjardingslov sandy loam and the Ultuna clay loam, were investigated by X-ray diffr action technique (XRD). Semiquantitative estimates of the mineralogy w ere made based on diffractograms from oriented samples. The Kjettsling e soil consisted predominantly of vermiculite, with mica being the nex t most abundant mineral. In the Ultuna soil, mica was the dominating m ineral and vermiculite occurred in lesser amounts. Smectite was presen t only in the Fjardingslov soil where it was the major mineral in the medium/fine clay fraction (<0.2 mum). Small amounts of kaolinite were found in the three soils, and chlorite was detected in all silt fracti ons as well as in the coarse clay fraction of the Ultuna soil. Mixed-l ayer vermiculite-chlorite was detected in the Kjettslinge soil (2-20 m um), indicating that chlorite had weathered to vermiculite. Quartz, K- feldspars, plagioclase feldspars and amphiboles were present in all me dium/fine silt and coarse clay fractions. The mineralogical compositio ns of the Fjardingslov and Ultuna soils were-in accordance with the fi ndings of earlier studies, whereas the vermiculite content in the Kjet tslinge soil was apparently higher.