http://pec.lib.wvu.edu/record/P177401933The Phosphorus concentration of the exuded sap of corn as a measure of the available phosphorus in the soil.Journal article reprint from: <em>Journal of the American Society of Agronomy</em>, v.25:no.2 (1933:Feb.).Pierre, W. H. (William Henry), 1898-Pohlman, G. G. (George Gordon), 1902-Soils--Phosphorus content.Sap.Phosphorus in agriculture.Corn--Analysis.14256