ABSTRACT:
Water runoff and soil loss from fall-sown wheat (Triticum aestivum L.) fields are often severe during the winter when rain or snow melt occur on frozen soils in the inland Pacific Northwest (PNW). In a 2-year field study near Benge, WA, we tilled planted wheat plots on slopes > 40% in late fall to a depth of 25 or 60 cm with shanks spaced 3.7 or 6.0 m apart. In a dry winter, no soil loss was measured in ripped plots compared to 3.0 t ha−1 soil loss for the control. Soil drying occurred near the tillage channels in ripped plots, reducing over-winter soil water storage. In a winter with higher than average precipitation and frequent frozen soil conditions, soil loss was 6.4 and 20.2 t ha−1 for ripped and control treatments, respectively. Ripping significantly improved water infiltration into the soil to a depth of 180 cm as far as 90 cm down-slope from the tillage channel. In both years, grain yield was reduced in the row most disturbed by the tillage shank, but was increased in adjacent rows. On a whole-plot basis, there were no differences in grain yield between ripped and control treatments either year. Results suggest that deep ripping planted wheat fields in late fall is an effective soil and water conservation practice that does not reduce grain yield.
Footnotes
William F. Schillinger is a dryland research agronomist, Department of Crop and Soil Sciences, Washington State University, Ritzville, Washington 99169; Dale E. Wilkins is an agricultural engineer, USDA-ARS Columbia Plateau Conservation Research Center, Pendleton, OR 97801. Washington State University Crop and Soil Sciences Department Technical Paper no. 9511-33. This research was funded by the Washington Wheat Commission and the WSU Water Quality Program. The authors thank WSU and USDA-ARS Agricultural Research Technicians Harry Schafer, Craig Cameron, and Daryl Haasch for their competent technical assistance. The cooperation and enthusiasm of wheat grower Harold Cli-nesmith and his donation of land, equipment, and time is gratefully acknowledged. Appreciation is extended to John Zuzel and Joseph Pikul for their technical expertise and encouragement.
- Copyright 1997 by the Soil and Water Conservation Society
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