Development and concept evaluation of an on-the-go soil strength measurement system

Root-restricting soil layers reduce crop yields in the southeastern U.S. almost every year due to temporary periods of drought. Subsoiling beneath these layers is an annual practice for most farmers in this region as a method of removing this barrier and improving rooting conditions. Currently, farmers could use a soil cone penetrometer to determine the depth of their root-restrictive layer in a few locations within afield and then set their tillage depth to exceed the deepest root-restricting layer found. However, the potential for significant energy savings exists if some method of sensing the depth of this layer was available on-the-go and adjustments could in turn be made to subsoiling depth. A prototype design of an on-the-go soil strength sensor was developed as a possible alternative to the cone penetrometer and as a method of sensing the depth of the root-restricting layer. Several versions of this sensor were evaluated in a sandy loam soil bin at the USDA-ARS National Soil Dynamics Laboratory. The sensor was able to detect compacted soil profiles in a similar fashion as the cone penetrometer. The on-the-go soil strength measurements were more closely correlated to bulk density than the cone penetrometer measurements and exhibited less variation than cone penetrometer measurements. Further research with this sensor could lead to methods of quickly and easily mapping soil compaction within fields.