Four stoppered jars containing samples of commercial fertilizer and concentrated fertilizer mixtures produced at the Arlington Experimental Farm in Arlington, Virginia. Established by an act of Congress in April 1900, Arlington Farm served as the main field laboratory for the Bureau of Soils, U.S. Department of Agriculture, until 1941. The purpose of this photograph was to compare the relative bulk of ordinary commercial fertilizer, as seen in the two jars on the left, relative to concentrated fertilizer mixtures consisting of the same plant food content, as seen in the two jars on the right.