Author
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Williams, John |
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Robertson, David - Dave |
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Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only Publication Acceptance Date: 1/30/2006 Publication Date: 6/24/2006 Citation: Williams, J.D., Robertson, D.S. 2006. No-till farming practices on the Columbia Plateau; changes in field erosion and stormflow. In Proceedings of the SWCS International Environmental Management Conference, July 22-26, Keystone, CO. 2006.CDROM. Interpretive Summary: Early farming practices on the Columbia Plateau led to excessive soil loss, lower cropland productivity, fouled in-stream habitat for aquatic life, and deposition of sediment streams and rivers. Presently much of the sediment transported during stormflow appears to originate from stream bank erosion, although annual infield erosion is still observed. We measured runoff and soil eroded from small watersheds used for dryland (non-irrigated) small grain crop production for three years that were managed using notill or conventional inversion tillage practices. Total annual erosion from the notilled treatment was 1% of the soil eroded from the conventionally tilled treatment. Notill practices effectively controlled runoff and erosion, at scales both larger than and smaller than the conventionally tilled area. These results demonstrate the immediate soil and water conservation effectiveness of notill technology. They also portend changes in the downstream processes as channels adjust to reduced stormflow volume and energy, and a reduced sediment supply. Technical Abstract: Early farming practices on the Columbia Plateau led to excessive soil loss; lower cropland productivity, fouled in-stream habitat for andronomous and non-andronomous salmonids and eels, and deposition of sediment in first, second, third and fourth order stream channels. Presently much of the sediment transported during stormflow appears to originate from stream bank erosion, although annual infield erosion is still observed. Four first order drainages, and one hillslope were instrumented with flumes and storm sediment samplers, with areas, respectfully, 25.0, 18.1, 10.4, and 6.2 ha, and 1.6 ha. The 6.2 ha drainage was managed using fallow and inversion tillage practices. All other drainages, and the hillslope site, were notilled. The total crop year precipitation ranged from 286 mm during crop year 2005 to 440 mm during crop year 2003. In runoff events from October, 2002 to September, 2005, the conventionally tilled drainage yielded 5.1 mm stormflow, whereas the notilled drainages yielded 0.7 mm. Total annual erosion from the conventionally tilled drainage was 391 kg/ha and 3.5 kg/ha from the notilled drainages. Notill practices effectively controlled runoff and erosion, at scales both larger than and smaller than the conventionally tilled area. These results demonstrate the immediate soil and water conservation effectiveness of notill technology. They also portend changes in the downstream processes as channels adjust to reduced stormflow volume and energy, and a reduced sediment supply. |
