Mulches, microclimate, topsoil and the establishment of vegetative cover on a dispersible soil

Abstract

Stabilization by vegetation of dispersible subsoil batters which cannot be adequately topsoiled has generally proven unsuccessful.

Straw and bitumen mulches were used alone and combined to aid the establishment of pasture grasses and legumes on batters composed of dispersible subsoil, which were covered with either 5 cm or 10 cm of topsoil, or were not topsoiled. The mulches consistently increased plant density, vegetative ground cover, and plant production. However, percentage ground cover at the end of the first season was only 10–26%, unless 10 cm of topsoil was added first. With 10 cm of topsoil, the only treatments to provide sufficient ground cover to control erosion after a year's growth were bitumen–straw and straw.

Cover was determined by individual plant growth rather than plant density. Field implications are discussed.