The featured chart presents an IEM calculation of daily soil water change by assuming that the two observations at depths of 12 and 24 inches are representative of a 6 to 30 inch depth layer. As such, the reported volumetric soil moisture values can be converted to a water depth over that layer. The top panel plots the end of day soil water depth and the bottom panel shows the day to day change for Nashua (NE Iowa). There are a number of interesting things to be seen with this plot as it starts off during the beginning of August when things were really dry and the soil was likely close to its wilting point (~12%) and no day to day decrease in moisture. The big rains of August then came and recharged the water in this layer. The initial big shot of rain (5 inches!) soaked into the layer and then you can see a large negative value the next day as this water moved to lower depths that were dry as well. The steady drying each day is noticeable as plants uptake water and drainage occurs to deeper depths.

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