Common Soil Moisture Response Function

The common soil moisture response function used in for example calculations of nitrification. The "Saturation Activity" is the value of the response function when the soil is saturated i.e. to the right in the figure. "Theta Upper and Lower Range" determines the optimum soil moisture content where the response function is equal to one. The “Theta Power Coefficient” determines the slope of the curve below and above the optimum range.