ARS | Publication request: Influence of long-term tillage and crop rotations on soil hydraulic properties in the U.S. Pacific Northwest

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 8, 2010
Publication Date: N/A

Interpretive Summary: No-tillage cereal production systems are being examined as alternatives to the traditional tillage-based wheat/fallow system for reducing wind erosion in the Columbia Plateau region of the Pacific Northwest. Although no-tillage has been found to enhance the physical structure of soils in more humid regions, there is a lack of information indicating whether the soil is better structured after using no-tillage as compared with traditional tillage in east-central Washington. We found after 11 years of no-tillage that the soil was more permeable to water, drained more rapidly, and had larger pores than in traditional tillage. These indicators of better soil structure, along with reduced wind erosion, provide environmental incentives for the adoption of no-tillage in the low precipitation zone of the Pacific Northwest.

Technical Abstract: In the semi-arid region of the Pacific Northwest, USA, no-tillage continuous spring cereal and spring cereal/chemical fallow rotations are being examined as alternatives to the traditional winter wheat/summer fallow rotation for improving soil and water conservation. There is limited information, however, regarding the long-term effects of conservation tillage on soil hydraulic properties in the region. The objective of this study was therefore to characterize infiltration, water retention, saturated hydraulic conductivity and bulk density of a silt loam soil 11 years after establishing tillage and crop rotations in east-central Washington. Treatments examined included no-tillage continuous spring wheat - spring barley (NTSW/SB), no-tillage spring wheat - chemical fallow (NTSW/ChF), and traditional winter wheat - summer fallow (WW/SF). Soil properties measured in spring and late summer 2006 included saturated hydraulic conductivity by the falling-head method, infiltration using a double-ring infiltrometer, and water retention characteristics by examining the temporal variation of in-situ soil water content. No-tillage continuous spring cereal (NTSW/SB) resulted in higher infiltration and saturated hydraulic conductivity, lower bulk density, and larger pores in the upper soil profile than the other treatments (WW/SF, NTSW/ChF). Infiltration and saturated hydraulic conductivity were lower for chemical fallow than for traditional fallow in spring whereas hydraulic conductivity was lower for summer fallow than chemical fallow in late summer. Continuous spring cereal rotations appear to enhance pore size, infiltration, and drainage of soils in the semi-arid area of east-central Washington.