Northwest and Allee Research and Demonstration Farm
Soil moisture samples were taken at 29 sites in northwest Iowa during the last week of October 2001. Moisture samples were pulled at 1-foot increments, down to a 5-foot depth. Samples were weighed, oven dried, and reweighed at the Sutherland research farm. Moisture percentage was calculated from these data, then used to calculate inches of plant-available moisture in the soil.
Iowa State University
DeJong, Joel L. and Kassel, Paul C., "Soil Moisture" (2002). Iowa State Research Farm Progress Reports. 1610.