Sampling wet, sticky soils can be very frustrating. Wet, sticky soils are more likely to plug soil probes and result in poor quality soil cores. If you are soil sampling and only half of the soil cores are full length (good quality), that’s bad! For every poor quality core that you have to throw away, more time is needed to take another good quality core. Time is precious, so you want to do whatever it takes to reduce plugging and get good quality soil cores every time.
AGVISE Laboratories has been manufacturing and selling hydraulic soil sampling equipment for over 30 years. Based on trial and error, we have developed soil sampling probes and tips that greatly reduce issues with plugging from wet, sticky soil. The design of the soil probe tip is very important to reduce plugging. AGVISE developed the HD probe and tip several years ago, and it has become a customer favorite for wet soil conditions. The HD tip has a cutting edge, but it also has lip of relief just inside the end of the tip (see figure). This relief allows the wet soil core to expand after it passes through the tip, and not touch the probe wall, which reduces plugging. The HD probe body also has a slightly bigger diameter to allow the soil core to slide through more easily.
It is also important to use an approved lubricant when sampling wet, sticky soils. WD-40 is the only lubricant that has been tested by university research, so we know that it does not contaminate samples. Don’t use generics that have not been tested, as this could lead to contaminated samples. In the video below, you will see a PVC tube attached to the cylinder channel that acts as holster for the soil probe. This holster has about 3” of WD-40 in the bottom, so the bottom few inches of the probe gets lubricated in between each soil core. The first time I saw this PVC holster with WD-40 at the bottom was from one of our customers in Rolla, ND. I thought this was great idea and I have had one in my sampling vehicle for several years now!
We have created a short video using our HD probe and tip to collect soil cores in a very wet wheat stubble field (you can see very deep ruts from the combine in the background). The video shows the PVC holster with the WD-40 lubricant in the bottom. Our hydraulic systems are usually installed in the cab of the truck, but for the video it was better to have it mounted on the back so you can see everything better. The electric/hydraulic power unit easily pushes the HD probe in and out of the soil profile in about 10 seconds. The probe is attached to the cylinder shaft with our quicktatch collar. The full length soil core is shown afterward so you can see that even in these wet, sticky soils you can get good quality soil cores when you use the right equipment and the proper soil lubricant. If you have any questions, or would like to order one of our HD probes and tips, please give us a call at 701-587-6010.