Wednesday, November 7, 2007 - 9:45 AM
303-2

Assessing and Improving the Wind Erosion Control Attributes of Tillage Ridges.

Lawrence Hagen, USDA-ARS, 1801 Rocky Ford Circle, Manhattan, KS 66502

Tillage ridges are a major wind erosion control practice that may be used alone or in conjunction with other practices. Their use and importance in erosion control will likely increase in the future because of residue and manure removal for use in biofuel production, decreases in water available for irrigation, increases in acreage of low residue crops, and predicted increases in weather variability associated with climate change. Important attributes of ridges includes their height and spacing which then controls the aerodynamic surface roughness, surface wind shear stress distribution, trapping efficiency for saltating aggregates, and sheltered volume for storage of mobile soil. The abrasion resistance and cover of immobile clods or crust on tillage ridges determine the threshold velocities at which bare ridges began to erode and their durability during erosion events. There are a number of ways the erosion control of tillage ridges can be improved. These include orienting the ridge direction for maximum effectiveness normal to the most erosive seasonal winds and using small periodic changes in orientation to provide control when winds are not normal to the average ridge orientation. Simulations with the WEPS model will be used to demonstrate these effects. Tillage ridges composed of only mobile soil do not provide effective erosion control, unless various materials are used to armor them. Results from testing manure, soil stabilizers, and residue as surface armor on sandy ridges will be reported. Increasing the number and stability of immobile clod cover can also improve performance of tillage ridges. Using soil compaction or making clods water repellent are potential methods of achieving such improvements in their performance.