SHRINK-SWELL POTENTIAL AND CRACKING IN CLAY SOILS OF SASKATCHEWAN

Abstract

Clay soils in Saskatchewan were studied to understand their shrink-swell potential, to identify soil properties that predict the coefficient of linear extensibility (COLE), and to assess the extent of cracking during the growing season. The soils have medium to very high shrink-swell potential, which is related to the specific surface area associated with expandable clays. Because expandable clays in these soils are predominantly of fine clay size, COLE is reasonably well predicted from percent fine clay. The extent of cracking is estimated for some sites using an improved method of measurement. Limited data suggest that cracking intensity in native grassland is less than in cultivated sites and that, under wheat, it is more pronounced in subarid than in subhumid sites. The magnitude of cracking in clay soils of Saskatchewan is much lower than in warmer regions of the world. It is suggested that COLE values and the extent of cracking could be used in improving the classification of clay soils. Key words: Clay soils, COLE, shrink-swell potential, shrinkage, cracking, Saskatchewan