RELATION OF WATER-SOLUBLE BORON IN ILLINOIS SOILS TO BORON CONTENT OF ALFALFA

Abstract

Alfalfa and soil samples were taken from 40 identical locations in Illinois. Water-soluble B in the soil samples according to the Berger-Truog procedure was found to correlate with total B in plant samples as determined by the ignition-electrometric titration method of Wilcox (r = 0.848 with a regression factor of 2.5). B deficiency symptoms were usually observed when the B content in the plant was less than 20 ppm. and when water-soluble B in the soil was less than 0.5 ppm. The lower portions of plants showing the symptoms contained less B than the upper portions, while normal plants contained the same concn. of B throughout. In Illinois B deficiency of alfalfa is more common in dry seasons, is more prevalent on the older, more weathered soils, and is one of the factors influencing seed set.