Take the HyGround®!

A standard soil survey map (left) is compared to a Veris map (right), a soil sampling method used in HyGround soil management services.

Lower commodity prices mean growers need more efficiency from their operation. Fertilizer application is a big, but necessary, expense. In order for crops to grow, they need to eat, but the fertility across a field can vary. Some areas may be high, while the other side of the field may be low. Putting the same amount of fertilizer across the whole field is not very efficient.

Soil sampling is an essential way to find out the fertility across an entire field. We call this soil sampling process HyGround. HyGround is GPS soil sampling in the fall or spring, using a variety of sampling techniques. The most commonly used HyGround techniques are sampling 2.5 to 3.3 acre grids by soil type or electroconductivity.

Grid sampling and sampling by soil type are commonly used methods, but a lesser known method is sampling by electroconductivity. HyGround by electroconductivity involves using a machine called the Veris, which is pulled behind a truck or tractor. The Veris unit has six coulters that go into the ground. Two coulters in the middle send out an electrical current that is picked up by the other coulters. Clay particles conduct more current than silt, and silt conducts more than sand. The Veris is able to produce a map of the field showing the relative differences in soil texture throughout the field.

Unless dramatic changes are made to a field, the Veris unit only has to run over a field once because the soil texture of a field rarely changes. After the Veris is run over a field, a map is made from the electroconductivity information. The map is then divided into several different groups based on electroconductivity. The heavy soil areas are grouped together, the middle soil areas are grouped together and the lighter soil areas are grouped together. Soil samples are then taken from each of these different groups. Research shows that one soil sample taken per 15 acres using electroconductivity is equal to one sample in a 2.5 acre grid. However, most samplers will take one sample per 8-10 acres to be on the safe side.

The Veris electroconductivity sample is able to give us another layer of information about a field that can also be used for other tasks such as variable rate seeding and variable rate nitrogen.

Soil sampling frequency is also very important. At the InfoAg Conference this summer, Dr. Nathan Slaton from the University of Arkansas stated that potassium levels in the soil can vary widely from year to year and are not just dependent upon the yield taken off the field. This confirms research I did showing that yield only accounts for about half of the variation in phosphorus and potassium soil changes from year to year. This means that the more often soil samples are taken, the more accurate we can be with our fertilizer recommendations.

Efficiency is the key to getting the most out of that fertilizer dollar.

- Dr. Randy Simonson, North Central Division Agronomist