Submitted to: Pendleton Station Field Day
Publication Type: Experiment Station
Publication Acceptance Date: 2/15/1996
Publication Date: N/A
Interpretive Summary: One of the costs of our abundance of food is the loss of soil by erosion from our agricultural fields. Erosion from tilled fields can be reduced by tillage practices that leave rough porous surfaces covered by old crop residue. Measurement of resulting roughness and porosity can evaluate alternative tillage practices for effectiveness for erosion control. Current roughness and porosity measurements are either time consuming or rather approximate. The reflection of a sound of known intensity from a soil surface is influenced by both the roughness and porosity of that surface. If we are able to accurately relate the reflected sound to soil roughness and porosity, we will have a rapid accurate measure of soil surface condition. We will then be able to evaluate tillage and long term management practices and rapidly display their effect on soil erosion.
Technical Abstract: Measurement of soil surface roughness with current practices such as rill meters, comparative photographs or laser profile meters, provide a measure of the geometry of the soil surface. The porosity of the surface is not characterized by any of these methods. Acoustical measuring techniques have the potential for characterizing both the geometric shape and the porosity of a soil surface. Currently quantitative differences in porosity between surfaces of coarse sand and fine silt can be illustrated. Roughness effects provide qualitative effects that are quite apparent but are not yet predictable. The complexity of sound reflection from and absorption in a rough, porous soil surface is slowing the progress in developing an accurate theoretical description and practical measurement of the process.