Northwest and Allee Research and Demonstration Farm
Soil moisture samples were taken at 29 sites in northwest Iowa during late October 2005. Moisture samples were taken at 1-ft increments to a 5-ft depth. Samples were weighed, oven dried, and reweighed at the Sutherland Research Farm. The moisture percentages were calculated from these data, and then they were used to calculate the inches of plant available moisture in the soil.
Iowa State University
DeJong, Joel L. and Kassel, Paul C., "Soil Moisture" (2006). Iowa State Research Farm Progress Reports. 1138.