Mt. St. Helens Ash: Considerations of its fallout on rangelands

Field and laboratory studies were conducted on volcanic ash from Yakima, Moses Lake, Spokane, Washington, and Moscow, Idaho, three weeks after the May 18, 1980, eruption of Mt. St. Helens in southwestern Washington. These studies examined 1) the chemical, physical, and water retentivity properties of the ash, 2) the effect of the ash upon germination and emergence of crested wheatgrass and cheatgrass, 3) the impact of ash upon in vitro digestion of common forages fed to cattle and the rate-of-passage of ash in steers, and 4) the influence of the ash layer on water infiltration into a range soil and the amount of sediments in the runoff water. In addition to the above short term studies, small field plots of various ash treatments were initiated to monitor the effects of the ash over the long term, both on individual native plants and the native and seeded plant community. These field studies are being conducted in an environment similar to that on which the ash fallout occurred and will allow ash response to be compared with absolute control areas of no ash