THE INFLUENCE OF MOUNT ST. HELENS VOLCANIC ASH ON PLANT GROWTH AND NUTRIENT UPTAKE 1

Abstract

Concern has been expressed that the ash from the eruption of Mount St. Helens on 18 May 1980 may create potential crop management problems. The objectives of this study were: (1) to determine the effect of large amounts of the Mount St. Helens ash when mixed into a northern Idaho soil on total phytomass production of wheat (Triticum aestivum L. cv. Nugaines), peas (Pisum sativum cv. Alaska), and alfalfa (Medicago sativa cv. Atlas), under greenhouse conditions; and (2) to determine the effect of volcanic ash-Palouse soil mixtures on the nutrient concentration and total uptake of P, S, Ca, Mg, Cu, Fe, Mn, and Zn in wheat. Wheat, peas, and alfalfa were grown in a Palouse silt loam (fime-silty, mixed, mesic, Pachic Ultic Haploxeroll) amended with different levels of volcanic ash in the greenhouse. Total plant phytomass and nutrient content data were measured. Palouse soils amended with low to moderate levels of volcanic ash were found to positively influence total phytomass yield of wheat, peas, and alfalfa, although growth of all three crops was depressed under 100 percent ash treatments. Plant tissue concentrations of P and Ca were greater in 100 percent Palouse soil treatments than in pure volcanic ash; however, Mg and S levels were greater in the ash-amended treatments than in the 100 percent soil.