Received for publication November 30, 1978. Scientific paper No. 5242. College of Agriculture Research Center, Washington State University, Pullan. Project No. 1984. This study supported in part by a grant from the Washington State Potato Commission. The assistance of Dr. A1 Halvorson, WSU Soil Testing Lab, and Dr. C. G. Woodbridge, Prof., Horticulture, retired, in the arcillite and plant analyses is gratefully acknowledged.
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Assistant Professor and Research Technologist, respectively.