What’s the value of topsoil? It’s something most people likely don’t think about when it comes to farming.

Crop fields have topsoil to varying degrees, and while some fields are droughtier than others, on average yields are consistent across an operation.

Most farmers don’t like to see erosion and are concerned after a heavy rain when gullies are most likely to form; however, even if you’re in a no-till system you still have soil loss occurring on every farm.

It’s something you don’t see unless you are really looking for it, but on a typical no-till corn and soybean field in Butler County you’ll likely average somewhere between 1 to 2 tons per year.

It’s easy to miss — 5 tons of soil loss is about the thickness of a dime, but over time it adds up.

So, what is the value of topsoil then?

A study by the University of Missouri looked at long-term soil erosion and the impact on yield and we’ll take some of their results and apply them to Butler County.

On the Missouri research farm, they looked at corn and soybean yield and compared them to the thickness of topsoil. They found on average corn had a yield of 2.9 bushels per inch of topsoil and for soybeans the yield was 0.7 bushels per inch.

If we look at a common no-till farm in Butler County, on average your soil is eroding at around 2 tons per acre per year, or 0.282 inches per year. Pretty hard to see but let’s say we’ve been no-tilling that field for 20 years. Now we’ve eroded over 5.6 inches of soil.

What does that mean in yield? Referring back to the Missouri study on yield per inch of topsoil, soybeans are losing almost 4 bushels per acre and on corn we’re losing more than 16 bushels.

If we average the price of corn and soybeans over that 20-year period, we find that when we plant beans we’ve lost $35/acre and on corn we’ve lost $59/acre. Combined we’ve lost $47 per acre or essentially, we’re losing nearly $3 per acre per year by simply planting a crop.

This is assuming we’re getting an even erosion rate across a field, which in many cases isn’t true, so there are many parts of a field that are eroding significantly worse and other sections that have less erosion. However, all sections are eroding soil.

Factor in gully erosion, even small amounts, and the soil loss rates are even higher.

So how can we address this? Add cover crops.

By simply adding a cover to a corn and bean rotation we can cut erosion in half. Adding diverse covers and longer growing times further reduces erosion rates.

While the erosion reduction alone won’t pay for cover crops, the added benefits that covers provide — nutrient cycling, water holding capacity, improved drainage and weed control — means covers will pay for themselves.

Contact our office for more information on how cover crops can save you money and soil.

Andy Gaver is a conservationist with the USDA Natural Resources Conservation Service in Butler County.