CHEMICAL REPELLENTS TO REDUCE GRAZING INTENSITY ON RECLAIMED SITES

Revegetation of disturbed rangelands in western Canada is severely imp eded by cattle grazing. Fencing to protect emergent vegetation is cost ly and restricts animal movement. Chemically repelling cattle from eme rgent vegetation may provide a convenient and economical alternative t o fencing. This study determined whether certain repellents could redu ce grazing intensity on vegetation to which they were applied compared to untreated vegetation. Canopy measurements were used to compare gra zing intensity. Three trials were conducted on reclaimed land within t he Aspen Parkland region of central Alberta. Time since reclamation wa s over 10 years in Trial A, 2 years in Trial B, and 3 weeks in Trial C . Pregnant mares' urine, Hinder(R) (150 mg ml-1 ammonium soaps), Skoot (R) (120 mg ml-1 tetramethylthiuram disulfide), and Deer-Away Big Game Repellent(R) (37% putrescent egg solids) were evaluated. Two concentr ations of each repellent were sprayed onto 1 X 3-m treatment plots ran domized within blocks replicated 4 to 6 times. Plot canopies were meas ured either by gently resting a sheet of plastic laminate over the can opy, or by lowering a sliding bar attached perpendicularly to a meter stick until it contacted the uppermost leaves of the canopy, and recor ding the height of the sheet or bar above the soil surface. Canopies o f plots treated with Big Game Repellent(R) were taller than control pl ot canopies on each measurement date in all trials, indicating grazing was reduced. Big Game Repellent(R) plots were also generally taller t han plots treated with other repellents. Canopies of plots treated wit h pregnant mares' urine, Hinder(R), and Skoot(R) generally did not dif fer from control plots, nor did they differ from each other in any tri al. Low repellent concentrations did not reduce grazing in any trial, but high concentrations reduced grazing in all trials. Repellent effec tiveness was not permanent since all canopy measurements became shorte r with time. Big Game Repellent(R) was effective in reducing grazing i ntensity by cattle, but practical use of repellents for grazing manage ment requires further investigation.