Methods for Successful Afforestation of a Weed Infested Clay Soil

The effects of plowing and tilling, fertilization, and chemical weed control on survival and height growth of newly planted seedlings of black locust, silver maple, white ash, white pine, and white spruce were investigated in a non-replicated study in southern Ontario. Cost-benefit relationships of treatments were computed. Plowing and tilling improved growth of all species with average increases ranging from 37 per cent for white spruce to 750 per cent for white ash. Plowing and tilling plus weed control greatly improved growth of all hardwood species and resulted in the most favourable growth-cost relationship. Fertilization improved growth of locust, ash, and maple by 200, 500, and 700 per cent respectively, but failed to increase conifer growth. Application of 12 pounds of simazine increased ash mortality by 67 per cent. White spruce was subject to severe frost heaving following complete weed control.