Western Research and Demonstration Farm
Soil moisture is critical for crop production in most years in northwest and west central Iowa. Soil moisture samples were taken at twenty sites in northwest and west central Iowa during the last few days of October 2012. Moisture samples were taken at 1-ft increments down to a 5-ft depth. Samples were weighed, oven dried, and reweighed at the Northwest Research Farm. The moisture percentage was calculated from these data, and then used to calculate the inches of plant available moisture in the soil.
Iowa State University
DeJong, Joel L. and Kassel, Paul C., "Soil Moisture" (2013). Iowa State Research Farm Progress Reports. 1994.