Northern Research and Demonstration Farm
It has become common to see large-scale egglaying units in many parts of Iowa. Although most plants ship the eggs intact, some facilities also ship liquid eggs. At these locations, the eggshells are ground, stockpiled, and applied to farm fields. Farmers want to know if the eggshells have value as a liming source, and if so, at what rate they should be applied.
Iowa State University
Holmes, John D. and Rueber, David, "Use of Ground Eggshells as a Liming Source" (2010). Iowa State Research Farm Progress Reports. 408.