Cover Crops: Benefits and Considerations

Cover crops are a relatively well-established practice in the organic farming community that have gained significant traction among conventional farmers as well. There are several reasons to consider adding a cover crop or mix to your management plan, and it’s important to understand which species will help achieve the desired results. There may be financial incentives and grants available through the USDA-Natural Resource Conservation Service (NRCS). Talk to your local NRCS extension agent for more information and guidance regarding possible cover crop conservation and incentive programs.

Here are some ways a cover crop can help your soil and pest management needs, and the species that can best meet these needs.    

Erosion Reduction

Cover crops are widely known for their role in managing soil erosion on both fallow and planted ground. Their coverage, root systems, and often quick establishment provides the necessary means to protect the soil and keep it in place during strong winds and heavy rain events, especially when utilized on hilly terrain. If the rate of soil formation outpaces that of soil loss, reduced erosion equates to greater soil depths. This may foster a more productive and sustainable cropping environment overall. Even in no-till fields, where around 40% of the residue is typically lost over the wintertime, cover crops can still serve a beneficial purpose in this type of system.

Recommended Species: Long-rooted, quick growing grasses, such as annual ryegrass, cereal rye, and oats are most ideal. However, any species can still adequately serve this purpose.

Nutrient Management and Fertility Optimization

Whether by adding nutrients to a soil or minimizing them being leached out, cover crops can serve multiple purposes in managing soil fertility. They are an effective tool that may be used to help promote more thorough and complete nitrogen cycling in crop production by adding, fixing and scavenging nitrogen. Cover crops may prevent leaching of nutrients from the soil by taking up excess amounts, which is often most beneficial in fields where manure is applied. Upon termination, decomposition of the cover crop will release previously scavenged nutrients over time, building a more fertile soil.

Recommended Species: Legumes, such as clovers, vetches, field peas, and cowpeas can help enhance soil fertility. Grasses and brassicas can be used for the purpose of nitrogen cycling and nutrient scavenging/uptake. 

Organic Matter and Soil Structure Optimization
Over a prolonged period of time and through consistent planting, cover crops have been shown to increase soil organic matter (OM) content, especially when incorporated (tilled) into or left on the surface of the soil. An increased amount of organic matter in a soil correlates to increased fertility, biological activity and healthy structure establishment. Cation exchange capacity (CEC) is provided by OM and is a key factor in soil fertility, as it provides the soil the ability to better hold onto nutrients while also making them more readily available to plants. Organic matter may also promote more biological activity which helps build healthy soil structure. A healthy soil structure promotes better water infiltration and decreases water and nutrient runoff from a field, protecting nearby waterways and keeping nutrients in the production system.

Recommended Species: Any species with a large root biomass, such as cereal rye, sorghum-sudan, sweet clover, and more.    

Alleviate Compaction
By having quicker growth and longer roots than a typical cash crop, cover crops have the unique ability to grow into and break through deeper soil layers. Through this increased soil penetration, additional pore space and channels are created, allowing for more moisture flow, gas exchange and biological activity that will ultimately help loosen the compacted layers – regardless of where they are.

Recommended Species: Species with long/deep root systems, such as radish, oats, and cereal rye. Caution should be considered with certain types of tillage radish as taproot size/depths, upon harvesting, may leave holes of sizeable widths that can cause injury or equipment damage. Stand monitoring is recommended.  

Enhance Soil Biology
To effectively obtain usable organic matter and mineralized nutrients, soil microorganisms must be present. Cover crops help promote a healthy environment for soil microbes to thrive, as they contribute to a healthy soil structure, which allows for adequate gas exchange and thereby, respiration. A thriving population of microorganisms may then increase the decomposition rate of residues, which adds more value to conservation tillage systems.

Recommended Species: Any species can serve this purpose well in terms of building soil structure, but legumes, such as vetches, clovers, peas, etc., will help optimize the environment for beneficial mycorrhizae (fungi) by continuing to foster symbiotic relationships.  

Weed Control
Cover crops can act as living weed control through a mechanism known as allelopathy, which involves the release of allelochemicals from a plant that inhibit the growth and establishment of other plants in close vicinity to it. The establishment of a canopy (soil shading) and nutrient availability may also provide the cover crop a competitive advantage to weeds, limiting their germination and ability to grow and compete in the same environment.

Recommended Species: Species that can provide a dense stand with ample surface shading, such as winter rye, annual ryegrass, oats, vetches, buckwheat, red clover, and cereal rye. 

Insect Pest Management
The relationship between cover crops and insect pests is subjective and may be very dynamic. In the same way that an established cover crop may attract beneficial insects to help mitigate in-season pests, it can also serve as a host for other unwanted insect pests to inhabit, such as armyworm, slugs, wireworms, seedcorn maggots, white grubs, etc.  Research has provided anecdotal evidence, however, that cover crops may be a helpful to use as a form of insect control, but it is important to weigh the risks and susceptibility of specific areas and fields before adopting them as a strategy.

Recommended Species: Attractants and habitat providers to beneficial insects, such as buckwheat (ladybugs, lacewings, tachinid and hover flies), clovers (ladybugs, minute pirate bugs, big-eyed bugs, tachinid flies and aphid midges), hairy vetch (minute pirate bugs, ladybugs), and cereals (ladybugs).

Contact your Golden Harvest Seed Advisor or agronomist for more information regarding cover crop management.  

Photos are either the property of Syngenta or used under agreement.
Syngenta hereby disclaims liability for third-party websites.