Effects of kaolinite and drying temperature on the persistence of soil water repellency induced by humic acids

Abstract

The effects of kaolinite additions and drying temperature on the persistence of soil water repellency, induced by humic acids from peat, were assessed in this study. It was found that additions of 5 and 10% kaolinite (referred to as the most effective material in combating the water repellency) did not result unambiguously in a decrease of the persistence of water repellency. In case of the higher humic acids contents, an increase of the persistence of water repellency was even noticed in comparison with the samples without kaolinite. Establishment (re-establishment) of water repellency was observed for the samples wetted to 30% after drying at temperatures of 30, 60°C (in both cases 36 of the 48 samples containing humic acids became water repellent) and after drying at 210°C (a few samples with the higher humic acids contents became slightly water repellent).