ABSTRACT:
Frozen soil is a major factor contributing to high soil erosion in the Columbia Basin and Plateau of Oregon and Washington. The coldest winter temperatures often occur when the ground is bare of snow. In the absence of snow cover, crop residue on the surface can provide thermal insulation of the soil and reduce the incidence and severity of soil frost. Soil frost was measured during four winters in northeastern Oregon. Residue and tillage treatments included standing stubble, fall-plow, fall-chisel, straw mulch, bare surface and winter wheat. Standing stubble consistently reduced the depth of frost penetration by an average of 35% compared to the bare surface. There was little difference in frost penetration between fall-plowed or chiseled stubble. Heat flux in the bare surface treatment was 40% greater than in the standing stubble treatment when clear skies and warm air temperatures characterized the thawing weather. Bare and stubble treatments thawed the same day even though the bare treatment was frozen to a deeper depth. In contrast, the standing stubble treatment thawed four days earlier than the bare surface treatment when the thawing weather was characterized by low air temperatures and overcast skies. These conditions are associated with the advance of moisture-laden cyclonic storms that can cause rainfall and subsequent erosion on the thawing soil.
Footnotes
J. L. Pikul, Jr., is a soil scientist and J. F. Zuzel is a hydrologist with the Columbia Plateau Conservation Research Center, Agricultural Research Service, U.S. Department of Agriculture, Pendleton, Oregon 97801, and R. N. Greenwalt is a research assistant at Oregon State University's Columbia Basin Conservation Research Center, Pendleton, 97801. This paper is a contribution from the ARS-USDA and Oregon State University, Columbia Basin/ Plateau Conservation Research Center, Pendleton, Oregon 97801. Oregon State University Agricultural Experiment Station Technical Paper No. 7594.
- Copyright 1986 by the Soil and Water Conservation Society
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