Hoffer, George N. (1887-1963) | Purdue University Libraries, Archives and Special Collections
George Hoffer, a chemist, came to Purdue to be a botanist. He was a professor of Biology. He led research starting with black flecks appearing in canned corn and ending with the discovery of extreme K deficiency in the soil. The black flecks were iron oxides. The corn kernels were two times normal in iron. The nodes on the stalks had black zones very high in iron. The soils were acid and low in P but liming and phosphorus did little good. There was a lot of fungus in the plant, but that wasn't the problem. Finally a North Carolina farmer pleaded for help. His 75 bushel corn fields were now yielding very little. Hoffer suggested including some crude sulfate of potash in a simple field experiment. Presto...the K tripled yields and it eliminated the flecks, the dark discolored nodes, the lodged stalks, and the prolific fungus growth.
Hoffer spread the word. K was deficient in all soils east of the Mississippi River. Rainfall is high and K can be leached out. Well, not everyone learned this lesson; so Hoffer, in his eighties still needed to push potash.
It is said that..."We Purdue types sample our soils with our "Hoffer" tubes while the rest of the world simply calls them sampling tubes."