MACRO‐ AND MICROMORPHOMETRIC INVESTIGATION ON SOIL‐DEXTRAN INTERACTIONS

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Abstract
Summary: The effect of three microbial dextrans of defined molecular weight, on shrinkage and porosity inside clods has been studied on two Italian clay soils, a Fluvisol and a Vertisol.Shrinkage was determined on dried soil samples using an electro‐optical apparatus. The same apparatus was also used to measure porosity and pore size distribution inside the clods. For this purpose large thin sections were prepared from cracked soil samples after shrinkage measurements.Dextrans influenced shrinkage and the size distribution of clods and cracks in the two soils. The major effect was found in the Fluvisol where the arrangement of cracks was changed visibly.The dextrans caused a marked increase in total porosity in the Fluvisol but had only a small effect in the Vertisol. In both soils the pore size distribution was changed resulting in a greater number of larger pores in the dextran treated samples.