Soil Regeneration using Cover Crops

August 21, 2023

One of the fastest ways to regenerate soil health is by having green, growing plants that are really healthy and producing a large volume of sugars and carbohydrates. In addition to fueling plant growth (by weight, 95% of plant biomass comes from these sugars and carbohydrates), some of the sugars are also sent out through the roots to feed soil biology and trigger faster reproduction and multiplication in soils. This leads to soils that have better structure and larger amounts of available nutrients, which of course leads to healthier cash crops the following season.

While this can certainly be done with cash crops, it is usually to the farmer’s benefit to find a way to fit cover crops into the rotation as well. Cover crops are particularly effective at regenerating soils. A common way to fit them into the rotation is to sow them in the fall and let them grow over winter instead of leaving the soil bare. This is a huge benefit because these cover crops continue to feed biology all winter instead of forcing them to deplete the soluble carbohydrate reserves in the soil. After all, they do need to eat so that they can stay alive.

However, it is not enough to know that cover crops are key to regenerating soils. We also have to implement them into the system. This not only means using them, but using them properly. Most times there is a benefit to using different combinations of them to achieve different things. In fact, it has been said that diversity is the key to regeneration, and I believe that it is a very important point.

We can start by looking at legumes, which I almost always like to see in a mix. Legumes, such as clover, hairy vetch, peas, soybeans, and alfalfa, all add nitrogen into the soil by fixing atmospheric nitrogen. That’s great because we need nitrogen, and the soil biology also needs it for optimal reproduction, but we also need it balanced with carbon to keep the soil stable and productive. So we can add other cover crops that produce more carbon into the mix which makes the blend more productive. That’s the power of diversity.

Oats is one of my favorite cover crops. It releases silica from the soil, acts as a reducing agent to make trace minerals more available to the following crop, helps detoxification, releases phosphorus, and generally makes for a looser, more productive soil. Oats also improve mycorrhizal fungi.

Mustard is a good choice if you have problems with nematodes and soil borne fungal pathogens, such as phytophthora, verticillium wilt, fusarium, timber rot, anthracnose, etc. It will also give you a looser soil.

Sorghum Sudan is often a good cover crop to use during the summer, because of all the root exudates that they produce. They can produce about 16 times more root exudates than corn, for example.

Also consider tap roots such as tillage radishes, yellow blossom sweet clover, safflower, phacelia, etc.

Before you decide what species to use, grab a pen and paper and write down what you are trying to accomplish. What challenges are you having? Do you need more nitrogen? More bees/pollinators? Better weed control? Do you want the crop to winter kill? Do you want to remediate compaction? Stimulate mycorrhizal fungi? Release phosphorus? Improve nematode control? Etc. Then ask a cover crop consultant to help you.  Let their knowledge go to work for you.

A parting thought: Why would we want to pay 12-month taxes for land that we only use for 6-7 month out of the year? Let’s make use of the rest of growing season as well – let’s use it to regenerate the soil.