When a grower sell his grain crop to a coop or mill, there is often a “correction factor” applied to the total amount of grain being sold to account for the volume and weight change to the grain as it is dried so it is standardized to a set moisture content. For corn the standard moisture content is 15.5% and 56 lb. per bushel, for soybeans it’s 13.0% moisture and 60 lb. per bushel and for wheat the base moisture is 13.5% and base weight is 60 pounds per bushel. The following references explain the calculations and provide examples.
Extension Fact Sheets
Understanding Grain Shrinkage and Expansion, S. Sadaka, G.G Atungulu, G. Olatunde, Bulletin FSA1078, University of Arkansas Extension, 2016.
Calculating Grain Weight Shrinkage in Corn Due to Mechanical Drying, D.R. Hicks, H.A. Cloud, Bulletin NCH 61 – National Corn Handbook, University of Iowa Extension, 1992.
Grain Shrinkage Factor Calculator, S. McNeil, University of Kentucky Extension.