Ecological Effect of a Clay Soil's Structure on Some Native Grass Roots

Abstract

Dense Clay Range soils have larger structure peds or groups of smaller peds in the upper part of the soil when moisture is at the wilting point than do Clayey Range soils of the same moisture and clay content. Large peds, which are bordered by cracks when dry, apparently constrict roots as they dry and hold the roots so that they are stretched across the bordering cracks. Blue grama and buffalograss grow on the Clayey Range soils and have a fine, spreading root system near the soil surface. However, these grasses do not grow on Dense Clay Range soils where presumably their fine roots are not strong enough to withstand the constricting and stretching forces. Western wheatgrass and green needlegrass have larger, more deeply placed roots which are more vertically oriented than the short grasses and are able to utilize subsoil moisture and grow on the Dense Clay soils.