Infiltration into a seasonally frozen agricultural soil

Low infiltration rates in frozen soil are a major contributor to water runoff, soil erosion, and sedimentation in the Pacific Northwest region of the United States. A rainfall simulator used as a sprinkler infiltrometer was employed to determine the infiltration characteristics for three tillage treatments: standing stubble, chiseled stubble, and newly seeded winter wheat after summer fallow. Infiltration measurements were conducted in the fall of 1984 directly after tillage, in the winter when the soil was frozen, and in the spring when the soil thawed. Infiltration in frozen soil was determined after frost had penetrated to a predetermined depth in each treatment. Final infiltration rates in unfrozen soil were greatest for the chiseled stubble and least for the winter wheat treatments. Frozen soil greatly reduced infiltration for the chiseledand standing-stubble treatments when compared to the rates measured in the fall and spring. No infiltration was observed on winter wheat while the soil was frozen.