Submitted to: Soil Erosion for 21st Century Symposium
Publication Type: Proceedings
Publication Acceptance Date: September 27, 2000
Publication Date: N/A
Interpretive Summary: Soil erosion is of particular concern during spring in the northern Corn Belt. In early spring, frozen soil can impede infiltration and thus enhance runoff and erosion. However, little data is available concerning erosion during a spring thaw sequence. We designed an erosion box to assess erosion from a thawing soil in the laboratory. The box is equipped with splash guards, drainage ports, frost tubes, and sidewall barriers. The design of the box curtails any preferential flow of water along the sidewall and allows for one dimensional soil thaw. Preliminary results suggest that with adequate subsurface drainage, soil loss by interrill erosion does not vary with thaw depth. Data obtained will be used to modify water runoff and soil erosion prediction equations by software developers and aid in the development of management guidelines to reduce soil erosion during the critical thaw period in northern climates.
Technical Abstract: Frozen soil can be a contributing factor to erosion in cold regions. Erosion caused by restrictive frozen layers is not well documented. Therefore, we designed an erosion box to assess the impact of depth of frozen soil on erosion. Simulated rainfall was applied to soil contained in a wooden box (20 x 40 cm) placed at the base of a 10-m raindrop tower. The box was equipped with splash guards, drainage ports, and frost tube. Barriers were placed at two depths around the inside perimeter of the box to minimize preferential flow of water along the sidewall. Soil was packed into the box to a known density, saturated, and then allowed to drain until the water potential at 5 cm was 33 kPa. The box was insulated on all sides and placed in a freezer until isothermal temperatures of -5 deg C were achieved throughout the profile. The box was then positioned at a 6% slope at the base of the raindrop tower. Simulated rain was applied at a rate of 56 mm h**-1 when the soil thawed to 2, 5, 10, or 20 cm. All drainage and runoff was collected during the simulation. The design of the box provided a near one-dimensional heat transport through the soil profile. With adequate subsurface drainage, soil loss by interrill erosion did not vary with thaw depth and was equivalent to 5 Mg ha**-1 in this study.