Which Soil Probe and Tip Performs Best with Different Soil Types and Moisture Conditions

The basis of soil testing revolves around obtaining good quality soil samples. In areas that use hydraulic sampling systems, people often ask, “What soil probe (probe body and probe tip) work best in my soils?”

AGVISE staff conducted a demonstration project to obtain an answer for that question. AGVISE carries different probe body and probe tip combinations to address different soil conditions. Our probe bodies are made from stainless-steel and heavy-duty chromoly-steel. Our probe tip designs include 1/2” cutting tip, 5/8” cutting tip, 3/4” cutting tip, 5/8” wet tip with recessed lip, and 11/16” heavy-duty tip with recessed lip. The heavy-duty tip fits only on the heavy-duty probe body.

We went to the field and used every probe body and probe tip combination to collect full 0-24” soil cores. We conducted this experiment on two highly contrasting soil types: a heavy clay loam soil (wet and dry conditions) and a loamy sand soil (dry condition). Results are shown in the figures below. All cores represent a 0-24” soil depth; the orange line and yellow background indicate the degree of soil core compression that occurs when using different soil probe designs.

For dry conditions, the 3/4” cutting tip worked best in clay loam and loamy sand soils. The 5/8” cutting tip worked will for the dry loamy sand, but it performed poorly in the dry clay loam. The 1/2” cutting tip did not work well for any soil types or moisture conditions.

For the wet, sticky clay loam soil, the best probe tips were those with a recessed lip. The recessed lip provides additional room inside the probe tip; this helps prevent the tip from plugging because the core does not touch the walls of the probe body. Both the wet tip for the stainless-steel probe body and the HD tip for the HD probe body worked well on the wet, sticky clay loam soil.

If you have questions on which probe body and probe tip combination will work best for your soils, please call our technical support staff. (Northwood, ND office 701-587-6010, Benson MN office 320-843-4109)