Received for publication December 13, 1978. Authorized for publication as paper No. 5656 in the journal series of the Pennsylvania Agricultural Experiment Station, University Park, PA. Part of a thesis submitted by the senior author in partial fulfillment for the PhD degree, The Pennsylvania State University, November 1977.
The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper must therefore be hereby marked advertisement solely to indicate this fact.
Present address – West Tennessee Experiment Station, Jackson, TN.
Professor of Plant Nutrition, Department of Horticulture, The Pennsylvania State University, University Park, PA 16802.