Breaking down cover crops with Dr. Jennifer Wells

Cover crops have received a lot of attention lately due to the launch of TruCarbon and other carbon offers in the marketplace.  While we know cover crops help sequester carbon, it is important to understand all the positive attributes they can contribute to your farming operation.  Cover crops are an incredible tool that help decrease erosion, improve soil health, enhance water availability, smother weeds, help control pests and diseases, increase biodiversity, keep nutrients where they are supposed to be and bring a host of other benefits to your farm. 

Soil is every grower’s biggest asset.  The ability to improve and maintain healthy soil for the next generation of farmers is an incredible gift.  The USDA Natural Resource Conservation Service (NRCS) has identified four basic principles to help growers do just that.  These are:

1. Keep the soil covered as much as possible.
2. Disturb the soil as little as possible.
3. Keep plants growing throughout the year to feed the soil.
4. Diversify crop rotations as much as possible, including cover crops.

Of these, all but one is accomplished by cover crops with the other being tillage. Cover crops are broadly defined as any non-cash crop grown in addition to the primary cash crop.  Many different types of plants can be used as cover crops, but you can broadly split them into four classes: grasses such as ryegrass and barley; legumes such as alfalfa or clover; brassicas such as radishes or turnips; and non-legume broadleaves such as spinach buckwheat or flax.  Each type has its own benefit.  To maximize the benefit of planting cover crops, it is common to mix several types providing multiple benefits in the same field.  To help select the best type for your field, it is important to identify your primary objective for adding them into your system.  A few of the benefits cover crops provide are:

• Sequester and cycle nutrients – Many cover crops, such as radishes, have deep root systems that can pull nutrients from deep within the soil profile making them available in the root zone of the crops that follow.  This type of cover could lower fertility requirements and improve yields and reduce nutrient runoff.
• Create a nitrogen source – Legumes are a popular cover crop because they have the ability to fix nitrogen and make it available for the subsequent crop.  Generally speaking, they can contribute enough nitrogen to lighten demand from outside sources, depending on growing conditions.
• Provide weed control – Many types of cover crops help provide weed suppression in the off season by directly competing with weeds for sunlight, moisture, and nutrients.  Keeping weeds out of the field and weed seed out of the soil bank can lower herbicide requirements in future crops.
• Build organic matter – All cover crops help in building organic matter in the soil.  As the leaves, roots and microorganisms break down into organic matter, they add carbon to the soil and increase soil quality and water holding capacity.
• Reduce soil erosion – When cover crops prosper and fill the brown gap that occurs between cropping rotations, roots from the cover crop hold tightly to the top layer of soil, keeping the soil in place and not lost to wind or water erosion.
• Break up soil compaction – Soil compaction intensifies from heavy farm traffic over saturated soils.  Cover crops, such as radishes, turnips, grasses and legumes can help loosen compacted soil, feed earthworms, which help ease compaction, and lead to much better soil structure.
• Add habitat for wildlife and shelter pollinators – Cover crops add diversity in the field and provide environments for wildlife in the off season.  Crop mixes that contain clover help feed and have a positive impact on native pollinators.

GETTING STARTED
While implementing a new practice like cover crops can seem like a daunting task, realistic expectations and planning can help ease some anxiety.  The whole farm doesn’t have to be converted year one.  Pick a field or two, think about the factors above, and decide what your soil health goal is for the field.  Knowing your goal or goals will help you choose the best species or mixture to plant.  Depending on the crop mix, you can plan for timing, equipment and labor, termination, and adjustments, if any, will need to be made to the subsequent crop.  In the first few years, some find it beneficial to leave a test strip or small area of the field without the cover crop so you can see the change year over year.   
 
PROFITABILITY
While cover crops improve soil health in many ways, they have also been shown to increase yields over time on subsequent crops.  Determining when cover crops pay for themselves is not as simple as adding up the first-year costs and looking for a first-year yield increase to cover said costs.  This should be viewed as a long-term investment in your soil health, which ideally will lead to lower inputs and higher yields in the future.  Utilizing the Profit Insights section of the Truterra™ Insights Engine is a great way to look at the costs of a cover crop vs the benefits of soil health, decreased erosion and lowered greenhouse gas emissions.  The thought of increasing soil health feels good, but seeing the metrics change in the tool and realizing all that you are gaining by implementing them into your cropping system can be a real eye opener.  If you need help utilizing the profit insights section of the Truterra™ Insights Engine, please reach out to your Truterra account manager. 

La Crosse Seed is Truterra’s preferred partner for conservation seed and support. La Crosse Seed has invested in a wide array of conservation seed solutions that extend beyond cover crops including native grass and wildflower seeds, as well as seed for wildlife habitat, waterways, buffer strips and more. In addition, Truterra collaborates with La Crosse Seed because of their focus on soil and water conservation. To get started with a conversation around planning your orders and arranging logistics for the season, contact La Crosse Seed today.

Sources
https://www.sare.org/publications/cover-crops/ecosystem-services/10-ways-cover-crops-enhance-soil-health/
https://sarep.ucdavis.edu/sustainable-ag/cover-crops
https://extension.psu.edu/forage-and-food-crops/cover-crops/species-and-varieties
Lacrosse Seed – Soil First Management Guide, 8^th Edition