Measuring soil roughness changes with an ultrasonic profiler.

ABSTRACT A non-contact ultrasonic profiler was developed to measure soil surface roughness. The profiler has a vertical accuracy of ± 3 mm, a horizontal resolution of 30 mm, and detects the highest point in a 2040 mm^ ±160 mm^ circular scan area. The profiler provides a convenient, non-contact means of accurately determining surface roughness parameters. Surface elevations were measured to evaluate changes in random roughness of three tillage treatments (chisel plow, moldboard plow, and field cultivator) with simulated rainfall. Random roughness decreased with rainfall. Consolidation of 30 to 50 mm occurred on all three treatments. Horizontal soil movement occurred on the chisel and moldboard treatments from the tillage tool ridges to the furrows. A decrease of approximately 60 mm of total relief was observed with soil lost from the ridges being deposited into the furrow. However, no such movement was observed in the field cultivator treatment. These results were consistent with earlier results obtained using a manually operated profiler.