Friction velocity and aerodynamic roughness of conventional and undercutter tillage within the Columbia Plateau, USA

• Published in: Soil & tillage research Vol. 105; no. 2; pp. 236 - 241
• Main Authors: Sharratt, Brenton, Feng, Guanglong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2009; [Amsterdam]: Elsevier Science; Elsevier
• Subjects: aerodynamics; Agronomy. Soil science and plant productions; Air quality; atmospheric circulation; Biological and medical sciences; Conservation tillage; conventional tillage; crop rotation; Cropping systems. Cultivation. Soil tillage; Dust emissions; fallow; friction; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; grain crops; Soil erosion, conservation, land management and development; Soil science; Soil tillage; soil-plant-atmosphere interactions; stubble; surface roughness; Tillage. Tending. Growth control; Triticum aestivum; undercutter tillage; Washington; Wind erosion; wind speed; winter wheat; Washington; United States; North America; America; Air quality; Wind erosion; Conservation tillage; Dust emissions; Dust; Soil tillage; Friction; Roughness; Soil science; Aerodynamic characteristic; Velocity
• ISSN: 0167-1987; 1879-3444
• DOI: 10.1016/j.still.2009.08.004

Friction velocity ( u * ) and aerodynamic roughness ( z o ) at the soil–plant–atmosphere interface affect wind erosion, but no attempts have been made to quantify these parameters as affected by tillage systems within the Columbia Plateau region of the Pacific Northwest United States. Wind velocity profiles above adjacent field plots (>2 ha), with plots subject to conventional or undercutter tillage during the summer fallow phase of a winter wheat–summer fallow rotation, were measured over 50 high wind events (wind velocities in excess of 6.4 m s −1 at a height of 3 m) during 2005 and 2006 near Lind, Washington to determine u * and z o of tillage treatments. Wheat stubble plots were subject to either conventional (disks) or undercutter (wide V-shaped blades) tillage in spring and then periodically rodweeded prior to sowing winter wheat in late summer. Prior to sowing, u * for conventional and undercutter tillage respectively averaged 0.36 and 0.46 m s −1 in 2005 and 0.38 and 0.40 m s −1 in 2006 while z o for conventional and undercutter tillage respectively averaged 2 and 7 mm in 2005 and 2 and 4 mm in 2006. The aerodynamically rougher surface of undercutter tillage was predicted to suppress vertical dust flux; this was collaborated with observations in the field where undercutter tillage reduced dust flux as compared with conventional disk tillage. Undercutter tillage, therefore, appears to be an effective management practice to roughen the surface and thereby suppress dust emissions from agricultural land subject to summer fallow within the Columbia Plateau.