Cover Crops Advantages, and Cultivation Practices
Today, we will be discussing cover crops advantages and their growing method and other cultural practices.
A cover crop is a crop of a specific plant that is grown mainly for the benefit of the soil rather than the crop yield. Cover crops are commonly used to suppress weeds, manage soil erosion, help build and improve soil fertility & quality, control diseases, and pests, and promote biodiversity.
Cover crops are typically grasses or legumes but can be comprised of other green plants. A cover crop is grown in the off-season before the field is required for growing the cash crop. In essence, a cover crop readies the land for a received cash crop.
Cover crops are plants grown outdoors for the use of enhancing the quality of the soil. They help create soil fertile, prevent erosion, regulate water, reduce weeds, increase biodiversity, and develop farming as a whole. These types of crops are used in landscaping to enhance the look of a property.
Cover crops stay low to the ground, are cheap to plant & don’t require much maintenance. Popular options for cover crops are buckwheat, clover, rye, field peas & sudangrass. Cover crops are mostly used in large fields or in-ground gardens rather than raised beds.
Organic gardening with Cover crops:
Cover crops are a very important element of sustainable agriculture. These crops add fertility to the soil without chemical fertilizers using biological nitrogen fixation. A cover crop can offer a natural way to reduce soil compaction, manage soil moisture, reduce overall energy use & provide additional forage for livestock.
Small farmers choose to grow specific cover crops based on their needs and goals & the overall requirements of the land they are working. Cover crops developed in summer are often used to fill in space during crop rotations, help amend the soil, or suppress weeds. Winter cover crops help hold soil in place over the winter & provide ground cover. These crops can fix nitrogen levels in the soil.
Advantages of cover crops:
Cover crops provide many soil health & environmental benefits. Some examples are;
Reduce soil compaction:
Compaction layers in the soil can limit water infiltration, aeration & the growth of cash crop roots. Certain cover crops can break up compaction layers in the soil, reducing overly-aggressive mechanical tillage. For no-till farmers, cover crops provide a non-mechanical method for repairing & maintaining an ideal soil structure.
Manage nitrogen & nutrients:
Nitrogen is most frequently, in large quantities, when there are no growing plants to conserve it. Keep living roots in your soil to scavenge nutrients and put Nitrogen back in the soil, making it available to cash crops. Legume cover crops are good for releasing nitrogen back into the soil.
Greater water infiltration & improves water-holding capacity:
Cover crop residue contributes to a reduction in evaporation, preserving moisture through drought periods. Residue increases water infiltration, as increased living matter in the soil increases soil’s capacity to absorb water down to the root zone.
Ground that is exposed to the elements is at a greater risk of erosion by wind & water runoff. This can mean the removal of the rich topsoil & the compaction of the soil underneath, making planting much harder. Cover crops help to stabilize the soil, prevent runoff and both binding the soil together & improving its structure.
Cover crops save permaculturist time and energy. Given all the nutrients that they give to the soil, there is no need for composting or mulching. This makes cover crops a good option when looking to develop the soil quality of a large area.
Types of Cover Crops
Grasses have fine, fibrous root systems that are well suited to holding soil in place & improving soil structure. Suitable grass species for cover crops are fast growing & relatively easy to kill, either chemically, mechanically or by winter weather. Grasses do not fix any nitrogen out of the atmosphere, but they can accumulate a large amount from the soil.
Leguminous crops are often good cover crops. Summer annual legumes, generally grown only during the summer, include soybeans, peas, and beans. Winter annual legumes that are generally planted in the fall & counted on to overwinter include crimson clover, hairy vetch, and subterranean clover. Some, like crimson clover & field peas, can overwinter only in regions with mild frost. Hairy vetch is able to withstand moderately severe winter weather. Biennials and perennials include red clover, white clover, sweet clover & alfalfa. Crops generally used as winter annuals can sometimes be grown as summer annuals in cold, short-season regions.
One of the main reasons for selecting legumes as cover crops is their ability to fix nitrogen from the atmosphere & add it to the soil. Legumes that produce a substantial amount of growth, such as hairy vetch & crimson clover, may supply over 100 pounds of nitrogen per acre to the next crop. Legumes such as field peas, big flower vetch, and red clover generally supply only 30 to 80 pounds of available nitrogen. Legumes provide other benefits, including attracting beneficial insects, helping control erosion, and adding organic matter to soils.
Commonly used legume cover crops: red clover, Field peas, Hairy vetch, White clover, berseem clover, sweet clover, and alfalfa.
These broadleaf crops may have a role as green manure crops & in providing a different plant species and root system for soil building. They cannot fix nitrogen out of the air, but they can absorb huge quantities from the soil. Most of these crops are not winter-hardy, so additional control measures are not generally required. However, do not allow them to go to seed, as the volunteer seed can become a major weed problem.
Commonly used Non-Legume Broadleaves cover crops: Buckwheat, and Oilseed radish.
Cocktails or Mixtures:
Although seeding & management of cover crop mixes or “cocktails” can become more complicated, planting them allows you to attain multiple objectives at once. Cover crop cocktails offer the best of both worlds by combining the benefits of grasses and legumes. Compared to pure stands of legumes or non-legumes, mixtures usually produce more overall biomass and nitrogen, tolerate adverse conditions. Also, increase winter survival, improve weed control, and attract a wider range of beneficial insects and pollinators. However, cocktails often cost more, can create too much residue, may be difficult to seed and normally require more complex management.
Cover crops can make multiple functions in an agroecosystem simultaneously; they are often developed for the sole purpose of preventing soil erosion. Soil erosion is a procedure that can irreparably reduce the productive capacity of an agroecosystem. Dense cover crop stands to slow down the velocity of rainfall before it contacts the soil surface, preventing soil splashing and erosive surface runoff. Additionally, vast cover crop root networks help the soil in place & increase soil porosity, creating suitable habitat networks for soil macrofauna. It keeps the enrichment of the soil, excellent for the next few years.
Soil and fertility management:
Cover crops maintain & improve soil fertility in a number of ways. Protection against soil loss from wind & water erosion is perhaps the most obvious soil benefit. Cover crops contribute indirectly to overall soil fertility & health by catching nutrients before they can leach out of the soil profile. Their roots can even help unlock some nutrients in the soil, converting them to more obtainable forms. The amount and availability of nutrients from cover crops will vary widely depending on such factors as species, planting date, plant biomass, residual soil fertility, and rainfall conditions.
Cover crops help stabilize yields & improve moisture availability in the face of the increasingly erratic weather. Cover crops take up water & usually allow you onto the field earlier than if you did not have a cover crop growing. Alternatively, if facing drought or practicing dryland farming, cover crops still help boost yields while being very capable of water use. If you use no-till farming, the cover crop mulch increases water infiltration & conserves moisture in the summer. Added carbon & root channels, in addition to increased soil pore space, help improve soil, water holding capacity in any tillage system.
Cover crop stands often compete well with weeds through the cover crop growth period. It can prevent most germinated weed seeds from completing their life cycle & reproducing. If the cover crop is flattened down on the soil surface rather than incorporated into the soil as green manure after its development is terminated, it can form a nearly impenetrable mat. This drastically reduces light transmittance to weed seeds, which in several cases reduces weed seed germination rates. Even when weed seeds develop, they often run out of stored energy for development before building the required structural capacity to break through the cover crop mulch layer. This is often termed the cover crop smother achieve.
Some cover crops suppress weeds both during growth & after death. During growth, these cover crops compete vigorously with weeds for obtainable space, light, and nutrients. After death, they smother the next flush of weeds by forming a mulch coating on the soil surface. In addition to competition-based or physical weed suppression, certain cover crops are known to suppress weeds during allelopathy. This occurs when definite biochemical cover crop compounds are degraded that happen to be toxic to, or inhibit seed germination of, other plant species. Some well-known examples of allelopathic cover crops are rye, hairy vetch, red clover, and sorghum-sudangrass.
The Agricultural Research Service (ARS) scientists examined how rye seeding rates & planting patterns affected cover crop production. The results show that planting more pounds per acre of rye increased the cover crops, making as well as decreased the number of weeds. A higher density of seeds planted per acre decreased the number of weeds & increased the yield of legume and oat production. The planting patterns, which consisted of either traditional rows or grid patterns, did not seem to create a significant impact on the cover crop production or on the weed production in either cover crop. The ARS scientists concluded that increased seeding rates must be an effective method of weed control.
Managing Cover crops:
Termination or killing of the cover crop must be critical for the success of the spring planted crop. Killing cover crops as late as feasible will maximize plant growth and residual nutrient accumulation while allowing sufficient time for the cover crop to decompose, release nutrients, and recharge soil moisture. Producers can be terminating cover crops by harvest, crimpers, frost, mowing, tillage & herbicides compatible with the following crop. When terminating cover crop consider the following:
- Spring termination not necessary for cover crops that do not overwinter.
- Terminate cover crop at least two weeks prior to planting the major crop to minimize the risk of reducing corn yields.
- Overwintering cover crops must be terminated when they create to regrow if the spring is exceptionally dry or the long-range forecast predicts dry conditions.
- Small grains must reduce corn yields similar to continuous corn. Plant chemicals released into the soil can inhibit the growth of corn & some weed species. This is why terminating the small grain cover crop 2 weeks prior to corn planting is critical.
- Consider increasing seeding rates for no-till corn by ten percent when preceded by small grain cover crop. Because the improved surface residue can interfere with planter operations & seed placement and the increased seedling mortality due to the allelopathic effects.
- Using a starter fertilizer to help the microbes decompose organic matter.
Seeding methods in Cover crops:
Some methods & equipment might include:
Broadcasting by air: Cover crops can be useful from a broadcast seeder mounted on an airplane. This practice works well for larger seeds like rye & wheat but is not recommended for small clover or grass seeds. Broadcasting by air allows for the overseeding of an existing crop or for planting when soils are too wet for ground seeding. Although seed germination might be slower and a higher seeding rate can be needed.
Broadcasting by ground: This is the most popular & accurate seeding method and may be done using spinners, drop tubes or air pressure. The main critical factor is accurately metering seed before it is spread. Make sure the seeding pattern is appropriate for complete & even ground cover. Different seeds have varying spread patterns based on their respective weights & heavier seeds spread further than lighter seeds. This can cause difficulties when heavier & lighter seed mixtures are applied. Broadcast seeders may be mounted on tractors, tillage tools or other implements.
Incorporation: Cover crop seeds generate better stands with shallow soil incorporation. Excellent results can be getting by combining broadcast seeding with a cultivator or other incorporating tillage tool. The combination chosen depends on when seeding takes place & what management practices are in effect. Most cover crop seeds are very small & do not need much soil cover, just good seed-to-soil contact.
Drilling: This is another good cover crop establishment process, as most drills are equipped with a legume or grass seed box. Drilling works well for metering small seeds (use the standard drill box for larger seeds) and gives good placement & seed-to-soil contact. Drilling can be particularly successful in no-till management systems.
The season for Planting:
Frost-seeding: Seeding a cover crop into a recognized crop in late winter to very early spring. Example: Seeding red clover into wheat in March month.
Inter-seeding: To prolong the cover crop growing period, it is sometimes possible to plant a cover crop into the growing cash crop. Careful consideration needs to be made regarding the stage of the cash crop, cover crop species selection & environmental conditions. Consult an experienced cover crop user to prevent issues such as cash crop yield loss (due to competition), reduced harvest efficiency & failed cover crop establishment. Examples: crimson clover seeded into corn at the V6 corn stage & annual ryegrass flown onto seed corn in late August in south-west Michigan.
Pre- or Post-season seeding: Cover crops must be planted early in the growing season before late-season vegetables or field crops or after cash crop harvest. Example: Cereal rye following potato harvest.
Cover crop seed is as important as the commercial seed application & the method used will affect seed germination rate and stand quality. Using equipment that allows accurate application at the correct rate will save money & help ensure sufficient cover. Since cover crop seed sizes & weights vary, it is important to match equipment to both the seed and management practice.
Cover crop effects on the agricultural pests are multi-faceted. With careful attention to cultivar choice, placement and timing, cover crops can reduce infestations by insects, diseases, nematodes & weeds. Cover crops that attract and retain beneficial insects when allowed to flower include buckwheat, clovers & brassicas. Cover crop mulches suppress weeds & reduce splashing of soil-borne pathogens onto leaves, while some, such as sudangrass, brassicas, and mustards, reduce populations of verticillium wilt and other soil pathogens. Other mulches have been exposed to suppress nematodes. In Michigan, for example, some potato growers report that two years of radish improve potato production & lowers pest control costs. Pest-fighting cover crop systems help minimize pesticide use, and as a result, cut costs & reduce your chemical exposure.
This biodiversity is the main part of attracting a wide variety of insects to plot. By planting cover crops rather than leaving bare earth, you will bring more species of insect to the site. Some insects will predate on others & so prevent populations booming which may impact upon your crop yield. Attracting insects also increases the number of pollinators on your site, helping propagate garden plants.
Some of the risks involved after planting:
Planting a cover crop does involve some risks & potential drawbacks. Proper planning & management of a cover crop can help minimize or eliminate risks, leading to a successful payback.
- Fields with heavy plant residues are more susceptible to increases in populations of soil insects such as cutworms, armyworms, and slugs. A process of control may be needed prior to planting a new crop. Proper pest scouting & treatment, if needed, can reduce the risk of damage by pests.
- The choice of the cover crop must be made with existing weed, disease, nematodes, and other soil problems in mind. Growing the wrong cover crop with inadequate rotations may generate a problem with diseases. The cover crop can increase the occurrence of a disease in the subsequent crop if it happens to be a host for the organism that causes the disease. For example, the use of a brassica cover crop such as a forage turnip can harbor insects & diseases for a brassica crop like broccoli.
- The cost of establishing & maintaining a cover crop may outweigh some of the benefits. The added cost of seed, planting, disking & incorporating the cover crop, and the possibility of planting delays, may make cover crops unfeasible for some farmers.
Maximum yield explains:
Cover crops are mainly used to prevent and manage soil erosion. As the number and density of cover crops increase, the speed of flowing water is reduced & the soil stays intact. Cover crops hold the position and increase the porosity of the soil & thus enrich the soil for a few more years.
Cover crops increase the fertility of the soil and are commonly known as green manure. They are highly useful in increasing nitrogen content, a primary plant nutrient. Having more crops planted in the soil means more organic matter, which directly contributes to the quality of the soil and produces healthier & better food.
Cover crops also help manage water and moisture levels in the soil and give tough competition to the unwanted weeds that grow in the soil. Some cover crops of little value can be used as baits to trick and distract pests of the better, more valuable crops. When used in this way, cover crops must be considered companion plants.
Read: Growing Cowpeas.