Skip to main content
ARS Home » Pacific West Area » Pendleton, Oregon » Columbia Plateau Conservation Research Center » Research » Publications at this Location » Publication #293092
Title: Soil and water conservation in the Pacific Northwest through no-tillage and intensified crop rotations

Author
item Williams, John
item Wuest, Stewart
item Long, Daniel

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2013
Publication Date: 11/1/2014
Citation: Williams, J.D., Wuest, S.B., Long, D.S. 2014. Soil and water conservation in the Pacific Northwest through no-tillage and intensified crop rotations. Journal of Soil and Water Conservation. 69(6):495-504.

Interpretive Summary: The winter wheat (Triticum aestivum L.) summer fallow rotation typically practiced in the intermediate precipitation zone (12-18 inches per year) of the inland Pacific Northwest has proven to be economically stable for producers in this region. However, multiple tillage operations are used to control weeds and retain seed-zone soil moisture, which disturbs the soil and makes it prone to substantial erosion. Alternatives to this system include no-tillage or minimum tillage in combination with increasing frequency and variety of crops grown. This paper is the final report and summary of three separate studies designed to compare runoff, soil erosion, and crop yields resulting from conventional disturbance till, no-tillage, or mulch tillage. The first site included two neighboring drainages with complex topography: one farmed using disturbance tillage with a 2-yr crop rotation and the other farmed using no-tillage with a 4-yr crop rotation Measurements were made at the outlets and on the slopes of the drainages. The second site was on a steep hillslope using either no-tillage or mulch tillage. The third site was a shallow draw in which no-tillage and mulch tillage with a 4-yr crop rotation were compared. The no-tillage treatments produced less runoff and soil erosion than either the disturbance or mulch tillage treatments at all three sites. The ratio of disturbance tillage to no-tillage runoff in the drainages was 10:1 at the outlets and 2:1 on the slopes, and in the draw experiment the ratio of 1.7:1. The ratios for soil erosion were 5:1 at the drainage outlet, 47:1 within the drainage, and 2:1 in the draw experiment. Ratios were not calculated for the hillslope experiment because the no-tillage treatment produced no runoff or soil erosion, whereas the annual runoff was 0.1 inches moving 0.1 tons of soil out of the field from the mulch tillage treatment. Winter wheat yields did not differ significantly among DT, MT, and NT. Broader acceptance of no-till cropping systems in the intermediate precipitation zone of this region would substantially decrease soil losses from farm fields and improve downstream water quality.

Technical Abstract: The winter wheat (Triticum aestivum L.) summer fallow rotation typically practiced in the intermediate precipitation zone [300-450 mm (12-18 in)] of the inland Pacific Northwest has proven to be economically stable for producers in this region. However multiple tillage operations are used to control weeds and retain seed-zone soil moisture, which disturbs the soil and makes it prone to substantial erosion. Alternatives to this system include no-tillage (NT) or minimum tillage (MT) in combination with increasing cropping intensity. The objective of this study was to compare runoff, soil erosion, and crop yields resulting from conventional disturbance till (DT), and NT or MT. Small collectors and flumes were used to quantify runoff and soil erosion from small drainages and slopes at three sites near Pendleton, OR. The first site included two neighboring drainages: one farmed using DT with a 2-yr crop rotation over 8-yr (2001-2008) and the other NT with a 4-yr crop rotation (2001-2008). The second site comprised a hillslope planted with different crops using NT over 8-yr (1998-2005) and MT over 3-yr (2006-2008). The third site was a shallow draw in which NT and CT with a 4-yr (2004-2008) crop rotation were compared. Runoff measured in flumes was significantly influenced by tillage method in the order of DT>NT in a ratio of 7:1 at the first site and MT>NT in a ratio of 16:1 at the second site. Soil erosion was found to be DT>NT in a ratio of 5:1 at the first site and 17:1 for the second site. For small collectors, runoff was DT>NT in a ratio of 48:1 for the first site in MT>NT in a ratio of 17:1 for the third site. Winter wheat yields did not differ significantly among DT, MT, and NT. Broader acceptance of no-till cropping systems in the intermediate precipitation zone of this region would substantially decrease soil losses from farm fields and improve downstream water quality.