Seeding Experiments on Highway Backslopes

Construction methods required to build modern highways lay bare extensive areas along the rights-of-way. These areas were previously left in an ungraded condition and no effort was made to establish a vegetative cover. Stands of soil-binding plants became established slowly by natural means; therefore these areas were unprotected and subject to costly and unsightly erosion. To prevent erosion and to facilitate the early establishment of a protective cover, present construction methods include grading and seeding these areas, mulching foreslopes and backslopes, and sodding of critical waterways. Stand establishment on such areas is more difficult than on areas with topsoil in place. Little experimental work has been done with the seeding of areas denuded of topsoil, and there is an urgent need for technical information concerning methods of stand establishment on these areas. In recognition of this need, the Iowa Highway Commission and the Iowa State College are cooperating in a study of the problems involved. Experimental seedings of grass-legume mixtures on backslopes of new construction have been studied for three years by measuring the response of certain grasses and legumes to determine which serve best to stabilize these slopes at a reasonable cost