September is not too late to plant cover crops

Cover crops, long touted as one fo the most versatile tools a farmer can use in his cropping systems, are often less expensive than other forms of land maintenance and preservation. And it's not too late to plant crops before autumn takes hold.



September 21, 2021 - 9:13 AM

Cover crops can provide weed suppression, build soil health, offer fall and spring grazing options, or offer a productive hay/silage crop to be sold or utilized on the farm. Photo by K-State Research and Extension

It is not too late to get some cover crops on wheat stubble or any fallow ground from flooded or failed crops this summer. Cover crops are one of the most versatile tools a farmer can use in his cropping systems. Depending on a farm’s goals, adding cover crops can provide weed suppression, build soil health, offer fall and spring grazing options, or offer a productive hay/silage crop to be sold or utilized on the farm. How could planting a cover crop now help meet your farm’s goals? 

Wheat stubble and fallow ground provide the perfect opportunity for weeds to thrive. While using herbicides is an option, and sometimes a necessary option, it can be hard to pencil in another round of herbicide costs in an already tough year. Herbicide applications on wheat stubble or bare fields can cost anywhere from $7 per acre all the way up to $20 per acre and still not achieve perfect results.

While most herbicide decisions have been made, and sprayers have made their passes, there are still opportunities for weeds to persist late in the summer, and early in the spring. Mustard, marestail, and downy brome are common weeds that will emerge in the late summer. Cover crops provide a cost-effective solution to give competition for those weeds that have escaped chemical control. While a cover crop may not kill already established weeds in a field, it will certainly prevent emergence of new weeds by blocking sunlight from hitting the soil and leaves of emerging weeds. 

Soil health is a long-time issue in southeast Kansas where our clay soils can have a variety of issues. The degradation of our soil’s physical properties, and our surface waters’ quality, can be easily linked to poor soil management that has happened for generations. In southeast Kansas, the low levels of soil organic matter allow for water run-off and soil erosion to occur. With that runoff, you not only lose soil, but pollute surface water as the nitrates and phosphates make their way into ponds, rivers, and lakes. Some easily noticeable effects from nitrate and phosphate runoff can be seen in the increasing occurrence of algae blooms in ponds and lakes. 

Generally, most farmers understand the importance of soil health, and the need to build our soil due to losses from soil erosion, but that may seem out of reach to many producers. Building the soil profile is not something that can be done in one growing season, or over the winter. It will take several years of good practices to begin to see a change in the soil’s structure. This length of time needed to promote any change to the soil may not seem worth it, when we can add the nutrients needed to produce a crop each year via fertilizers, but each year we neglect our soils’ health, we become more dependent on chemical fertilizers to maintain a crop. 

One of the best ways we can begin to rebuild our Southeast Kansas soils is to increase organic matter. Organic matter increases the water infiltration rate of the soil, and improves the water holding capacity of the soil. Meaning each time it rains, not only will less water (and nutrients) run off the field, that moisture will be available to the plant for a longer period of time while you wait for your next rain. Organic matter also increases the biological diversity of the soil. Having a variety of soil organisms such as earthworms, fungi, nematodes, bacteria and other soil microbes helps to completely break down plant matter to release essential nutrients. These organisms also help to build a stronger soil structure. 

Cover crops can be one step to increasing organic matter in the soil. Using high seeding rates of winter cereal crops is a popular way to add biomass, both above, and below the soil surface. Using “tillage” crops, such as turnips and radishes, helps to break up compacted soil, especially in no-till systems. 

Now that you have a cover crop in the field, it is tempting to take all of that new plant growth and use it for hay or silage, but if your goal is to build soil organic matter, leaving the residue in the field is essential. Organic matter does not simply grow when you have something growing in the field, it requires dead plant material to be broken down by soil organisms. One way to get a dual benefit from the cover crop could be to graze the forage in the field. By allowing the cattle to graze the crop in the field, you will still get some organic matter growth from the cattle manure. 

Cover crops such as cereal rye, winter wheat, triticale, and spring oats all offer fantastic grazing opportunities. With the exception of spring oats, most small grain crops will provide both fall and spring grazing. Using these small grain plants as a forage crop can produce large forage yields at varying times of the year. For example, a September planted spring oats will produce a much larger yield of fall forage than a winter cereal variety, but will not provide any spring forage. Conversely, a September planted winter wheat or triticale crop will provide smaller amounts of fall forage, but will yield multiple tons of spring forage in the spring. 

Mixing in additional crops can extend grazing periods. Adding in a forage turnip to one of your cereal grains can extend winter grazing further past a killing freeze. Selecting the correct cover crop or cover crop mix will require setting target grazing periods, and then selecting plants that will meet forage requirements during that period of time.

Hay cropping is a large portion of many farmers’ income, and cover crop can offer another cutting to be sold. While removing biomass from the field will limit any soil building cover crops can accomplish, the goals of many farms are to find more revenue. Planting the typical cereal crops after corn or soybean harvests can offer excellent haying opportunities in the spring, before planting the next year’s crop. 

Planting a quicker growing species, such as cereal rye, will allow the plant to reach the ideal cutting stage (pre-boot stage) well before any fields are ready to be planted. To avoid the wait of drying time, these crops can be wrapped for wet hay, or cut for silage at the same growth stage. 

Deciding how your farm can use cover crops, if at all, solely depends on having a clear goal set for the farm. You can use cover crops in a crop rotation to suppress weeds, or build soil health; or you can take advantage of fallow periods and use cover crops as a forage source for livestock. 

If you have any questions on how a cover crop could fit into your farm, contact Chad Guthrie at your county extension office, or at: [email protected].