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ARS Home » Pacific West Area » Pullman, Washington » Northwest Sustainable Agroecosystems Research » Research » Publications at this Location » Publication #94626
Title: SMALL GRAIN CANOPY COVER EFFECTS ON WATER EROSION

Author
item PANNKUK, C - WASHINGTON STATE UNIV.
item McCool, Donald
item Mutch, Paul

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 2/6/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Plant canopy is important in preventing water erosion from cropland. The main effect of the canopy is assumed to be absorption of the energy of the falling raindrops. Results of a three-year experiment at the Palouse Conservation Field Station near Pullman, Washington conducted by the Agricultural Research Service and Washington State University indicate benefits of a short small grain canopy may be greater where runoff from snowmelt and low intensity rains dominate the erosion process. For young fall-seeded small grain plants there is considerable leaf-soil contact during the high erosion period of winter and early spring. When wheat is planted in furrows up and down the slope, the stems and prostrate leaves may act to slow runoff and cause deposition of soil eroded from bare ridges between the furrows. For the conditions tested, part of the crop cover acts to protect the soil against runoff, similar to the effect of surface residue. Results of this study will improve design of crop management systems to protect soil and water quality.

Technical Abstract: In general, cover and management are the most important factors in preventing water erosion from cropland. The main effect of canopy cover is assumed to be absorption of the energy of falling raindrops. For a low canopy the erosion reduction is directly proportional to the percent ground cover. Small grain producers in the Northwestern Wheat and Range Region have frequently indicated this relationship does not adequately reflect th actual reduction in erosion caused by the crop cover. An experiment was initiated in 1995 by the Agricultural Research Service and Washington State University to determine the effect of crop cover on soil erosion. Bordered runoff plots were installed on up and downhill seeded areas at the Palouse Conservation Field Station near Pullman, WA. Different fall seeding dates provided a range of winter wheat crop cover values through the winter erosion season. Data from the three-year study indicates that for the tested conditions, the effect of the crop canopy in reducing erosion is greater than shown by current relationships. Negligible erosion was projected to occur at crop cover percentages of less than 100%. An exponential decay function provided a better fit of the data than did a linear relationship.