As we’ve learned in previous articles, improving soil health starts with minimal disturbance and keeping the soil covered as much as possible. But the real way to jump start soil health is to keep plants growing throughout the year to feed the soil.

Adding cover crops to a rotation increases root growth time from one-third of the year with traditional row crops to nearly two- thirds of the year with the addition of covers. To understand why this is important we need to understand the soil food web and how plants play the vital role in keeping the cycle moving.

As plants grow, there is a symbiotic and parasitic relationship between plant roots and bacteria, who feed on simple carbon sources. These bacteria can reproduce 5 billion offspring every 12 hours, providing a food source for larger soil microbes. As plants grow and their roots reach new areas the increase in bacteria increase exponentially.

In addition, fungi follow these root channels and create glomalin or the soil glue, the building blocks of air and water channels. These fungi can also have a symbiotic relationship with plants.

Mycorrhizal fungi carry nutrients to the plant roots as they act as root extensions branching out through the soil feeding and sharing the nutrients with the plant roots.

Fungi also feed on larger, more complex carbon sources breaking it down into simple forms for bacterial decomposition. There can be miles of fungi hyphae in an acre weighing anywhere from 1,000 to 15,000 pounds; as these fungi branch out the bacteria populations increase with them.

Furthermore, a healthy fungus population helps control many harmful fungi that can attack crops. While the previous two feed on plant material, protozoa and nematodes feed on bacteria and fungi mineralizing them for plant uptake.

On average, protozoa consume about 10,000 bacteria per day, bacteria weigh about a ton per acre carrying a 5/1 C:N ratio providing about 20 pounds of nitrogen that can be used by crops and other soil microbes.

The take home message is merely planting a two-crop system of corn and soybeans does not improve soil like a rotation that includes a long season cover crop.

Most of the microorganisms in the soil move very little during their life and if food is not present by them they cease to exist. The larger, more mobile organisms like nematodes have a harder time locating food sources and converting that to nutrients the crop can use.

By planting cover crops with large fibrous root systems that grow late into the fall and early in the spring, you can significantly increase microorganism populations. However, this shouldn’t be a once every three year occurrence.

By planting a cover crop each year you continually build the microherd allowing for faster residue breakdown and better water and air infiltration. Since this ecosystem follows a predator/prey model, significant decreases in food sources causes prey populations to rapidly decrease subsequently crashing predator populations.

Once food sources return, populations rebound but this can take years to occur.

Next month, we’ll look at how diversifying cover crop species can take the soil ecosystem to the next level.

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