Evaluation of Soil Moisture Measurements in Oklahoma as Soil Characteristics for Classification

Abstract Soil moisture measurements were evaluated as soil moisture characteristics specified in the new soil classification system. Soil moisture measurements were made with a neutron probe at about weekly intervals and were available for 3 to 6‐year periods at four sites with a range in mean annual precipitation of 45 cm to 80 cm. The cumulative days were counted when the soil moisture was below −15 atm pressure in either or both of the 0 to 23‐cm increment and the 23 to 38‐cm increment. The count was also made for the control section of the 23 to 38‐cm increment and the 38 to 53‐cm increment. The data yielded close fitting linear regression lines for cumulative days dry in each year against the measured precipitation for that year. The regression lines for the two tested control sections were nearly alike. The neutron probe method seems to be a satisfactory method for determining days dry. Some adjustment of the data will likely be necessary in translating the data for use in the classification system.