Cover Crops: Types And Benefits To Use In Agriculture

Planting cover crops is a common and rewarding farming practice that was applied as far back as in the Roman Empire. Since then, the method has been widely used in agriculture, bringing a lot of good. Farmers reap a plethora of cover crop benefits that fit versatile objectives, both in the short-term and long-term perspective.

Cover crops help prevent soil erosion, regulate moisture, attract pollinators, assist in weed and pest management, serve as mulch and the source of green manure and organic matter, and are used for grazing or forage. Depending on the types of cover crops, they add or uptake nitrogen.

What Are Cover Crops?

As the name hints, these are plants to cover soils for certain reasons. Unlike primary species, they support secondary farmer’s needs rather than are grown for trade or human consumption. They improve soil health, boost yields, and feed the cattle. However, it does not mean that these plants are some exclusive species. In alternative situations, they serve as cash cultures, and you can find them on the plate as well (for example, buckwheat or corn). The difference is that in the case of fall cover crops, these species are used as grasses.

Farmers plant them in different seasons, either fall or late spring/summer, uniformly or between rows. Some are winter-killed, and some require removal and residue management. They also suggest one species at a time or their mixtures. The latter method is reported to bring more prolific results. Common cover crops are legumes, grasses (forage grains), brassicas, turnips, radishes, etc.

This practice is strongly welcomed in crop rotation, no-till, and organic farming. Smart farming online tools assist in making knowledgeable decisions.

Types Of Cover Crops

There are three main categories, depending on their properties and options for use: grasses, legumes, and broadleaf non-legumes. In most cases, they combine several functions at a time, like preventing erosion, improving soil quality, serving for grazing, among others.

• Grasses are annual cereals like buckwheat, rye, wheat, corn, barley, oats, etc. They grow relatively fast and leave easily managed residues. Their fibrous threadlike root systems are strong and protect from erosion. In respect to nutrients, they accumulate soil nitrogen from the symbiosis with Azospirillum, yet do not possess the property to fix atmospheric nitrogen.

• Legumes enjoy the fame for nitrogen enrichment, as nitrogen-fixing cover crops. Their vigorous taproot system aids in tacking undesired undersurface compaction when plants grow big. Also, the bigger the plant is, the more nitrogen^{Cover Crops: Cover Crop Types. Ministry of Agriculture, Food and Rural Affairs. omafra.gov.on.ca} it can fix. Examples of legumes are crimson and white clover, cowpeas, alfalfa, hairy vetch, fava beans.
• Broadleaf non-legumes absorb soil nitrogen, hold the soil in place, and make green manure. They don’t require extra termination typically dying in the severe winter weather. However, non-legumes used as fall cover crops should be treated before seed settlement for weed control considerations. This type includes brassicas, forage radishes, turnips, marigold, mustards, and others.

Cover Crops By Season

Time to plant introduces another classification. Respectfully, agriculturalists distinguish fall, winter, spring, and summer types of cover crops. All of them have certain specifics in management, advantages and disadvantages.

Winter Cover Crops

These are mainly cereals planted after fall harvests of cash cultures. Their purpose is to serve as a natural ground “shield” until spring sows, not to bring yields. Basic requirements for their growth are enough warmth in the fall and sufficient moisture in the spring. They prevent soil erosion, combat weeds, conserve moisture, reduce leakage of nutrients but consume them as well. Also, their seeds require additional costs, may be hard to terminate, cause allelopathic effects, and interfere with primary culture development. Vegetation cover protects from diseases and pathogens, yet may produce quite the opposite results as well.

When planting cover agricultural species for winter, farmers should consider their resistance to frosts. Winter-hardy plants survive the harsh cold weather, while winter-killed ones are sensitive to considerable temperature drops and die during winter.

Summer Cover Crops

As the name suggests, this type grows in summer in-between primary species rotations. This practice is applied to defeat weeds, erosion, and adjust the earth for the next crop. Summer or spring cover crops also serve as fodder for livestock.

They prevent soil from quick drying with their roots compared to bare soils under the sunrays. Nevertheless, seeds may establish poorly in summer due to droughts and heat, induce nitrogen deficiency (unless these are legumes), require extra residue management, or longer time to decompose than expected, thus postponing the time for planting fall primary species.

As appears, the right time and correctly chosen agricultural cultures are the major keys to success, as benefits may easily turn into drawbacks when things go wrong. This is where EOSDA Crop Monitoring can help farmers to face the challenge, using historical data to elaborate productivity maps. Via comparative analysis, you can choose the optimal time and agricultural species.

Cover Crops For Grazing

Farm owners can ripe additional benefits with cover crops for grazing cattle. Such species possess general advantages and are used as animal food as well. Furthermore, grazing cover crops enable farmers to create a natural outdoor environment for breeding, which is important in organic agriculture. Grazing also provides animal manure on pastures, saves expenses on livestock fodder, and facilitates removal before primary culture planting. This practice is especially rewarding in late fall, winter, and early spring due to a lack of fresh and juicy vegetation cover.

Typical cover crops for grazing are cereals and legumes like ryegrass, wheat, sorghum, millet, oats, triticale, barley, hairy vetch, red and white clover, pennisetum, lablab, Austrian winter pea, cowpea, alfalfa, fava among others.

Benefits Of Cover Crops

Farmers plant cover crops to improve soil for certain reasons.

Soil Health And Fertility

Roots of cover crops help prevent erosion from water and wind. Some species can adjust nutrients to more ingestible forms for other cultures. Planting cover crops between rows, farmers get mulch as part of integrated weed management. Furthermore, flowering inter-row species attract pollinators. Shallow and deep-rooted cover crops penetrate soil on alternative levels, tackling compaction, and enhancing aeration.

Nitrogen Enrichment

Its concentration rises with legumes and decreases with non-legumes. Legumes are known as nitrogen producing cover crops. Nevertheless, they do not catch and convert gaseous molecular nitrogen from the air by themselves.

Cover crops that fix nitrogen are symbiotic with the process mediators on their roots – the soil-dwelling rhizobia bacteria^{Nitrogen Fixation by Legumes. Department of Extension Plant Sciences, New Mexico State University. 2015} (formerly classified as agrobacterium). In their turn, the bacteria get carbohydrates from the legumes. The nutrient mostly releases when nitrogen-fixing cover crops or the bacteria die and decompose. Rhizobium also decreases root diseases in plants, but the group representative Rhizobium radiobacter induces infections in humans.

Another biological alternative to convert atmospheric nitrogen into soil one is performed by the non-symbiotic cyanobacteria family. Otherwise, nitrogen is reduced to plant-ingestible forms industrially in the process of chemical synthesis.

Moisture Control

Cover crops can uptake excessive water after winter rainfall, enhance water infiltration (as well as soil aeration) with their roots, and retain moisture for the subsequent cash plants.

EOSDA Crop Monitoring enables farmers to check soil moisture on two levels: on the upper surface (5 cm) and the root zone.

Selecting And Managing Cover Crops

The choice of what culture to plant depends on its type and sequence. For example, legumes are beneficial for subsequent cash species for nitrogen supplies. Correspondingly, farmers should not seed them when nitrogen levels saturate.

A study calculated that nitrogen uptake in maize silage increased after Austrian winter peas and decreased after rye as much as 40 kg/ha in both cases^{Kaye, Jason et al. Managing nitrogen through cover crop species selection in the U.S. mid-Atlantic. PloS one vol. 14,4 e0215448. 12 Apr. 2019, doi:10.1371/journal.pone.0215448}, compared to fallow.

Another aspect to consider is the time required for proper cover plant decomposition. For example, buckwheat residue composts faster than barley or sorghum.

Cover Crops Management With EOSDA Crop Monitoring

The all-in-one software by EOSDA provides a wide spectrum of vegetation indices that draw a comprehensive picture of plant development. For example, NDVI helps to check the general state of vegetation and distinguish the most critical areas (to spot the urge in irrigation or fertilizers, for example). MSAVI allows controlling seedlings as it is not prone to the soil background. NDRE monitors nitrogen content via chlorophyll activity and aids in fertilizer applications as well as detects plant degradation.

EOSDA Crop Monitoring uses historical data on vegetation to elaborate productivity maps that allow agro specialists to reduce seeding and fertilizing costs. Retrieving information on crop phenological stages, farm owners can schedule field activities as certain operations like spraying and fertilizing must take place in a certain growth stage.

Past weather records give an opportunity to precipitate severe winters or summers. Weather forecasts enable farmers to efficiently schedule field activities like herbicide termination since some herbicides require dry weather, while others need rainfall to react.

Thus, the tool helps agriculturalists decide when to plant cover crops, how to treat them, and when to terminate them as well as record field operations with the activity log. Farmers can monitor the overall process of plant development, density, and health. Credible information promotes smart agro decisions and the team will assist in the software implementations.