Integrating Cover Crops in South Carolina Agroecosystems

When planning to integrate cover crops into an agroecosystem, farms and producers should consider a few different factors. This article discusses these factors, including desired benefits, timing of cover crops, soil and climate, and planting and termination methods. Specific sources for finding information are also provided to aid farmers and producers in making management decisions.

Why Integrate Cover Crops into a Rotation?

Cover crops (CCs) are crops planted to cover the soil and are typically planted between cash crop production cycles.¹ Cover crops are not harvested for yield but instead are left in the field.¹ Cover crops are gaining interest as a management practice to improve soil health and the overall agroecosystem.^2,3 In South Carolina specifically, soil erosion is one of the major concerns of agroecosystems.² Raindrops dislodge soil and transport soil particles to

Figure 1. Cover crops suppress weeds in a soybean field in Spartanburg County, South Carolina. Plot (a) is soybean planted after cover crop with visible residue, and Plot (b) is no cover crop before soybean leads to pigweed infestation. Plots (a) and (b) are directly next to each other in the same field. Photo credit Payton Davis.

surface waterways.⁴ The transported soil can cause sedimentation in surface waters, increasing nutrients and potentially other chemicals attached to the soil particles.⁵ Live canopy and residues of CCs can reduce rainfall droplet impact, helping to keep soil particles in place and thus reducing erosion and subsequent sedimentation.^{3, 6}

Other on-farm benefits from CCs include reducing nutrient losses,⁶ increasing availability of nutrients such as carbon and nitrogen,⁷ increasing soil microbial activity,⁶ enhancing carbon sequestration,⁸ suppressing weeds (figure 1),⁶ reducing soil compaction,⁸ and aiding in pest management.⁸ Additionally, CCs may reduce crop production costs and increase return on investment.^8,9

Groups of Cover Crops

Cover crops are commonly grouped by plant type. This method has three groups: legumes, grasses/grains, and brassicas. The three CC groups have different main benefits associated with them:

Legumes

Specific plants of the Fabaceae family have a symbiotic relationship with a specialized bacteria that transform atmospheric nitrogen into ammonia (a plant-available form of nitrogen).^10,11 The result is a plant that has a high nitrogen content that is then recycled back into the soil when the plant dies and begins to decompose, offering nitrogen to the subsequent crop.¹²

Grasses and grains

Known for dense rooting systems^13,14 and providing dense canopy coverage throughout the growing season, grasses and grains are also great for building up soil organic matter.^14,15 Increasing soil organic matter can increase moisture holding capacity,¹⁶ improve soil structure for plants to live in,^17,18 act as a nutrient storehouse,^17,18 and increase the microbial community.¹⁷ Certain grasses and grains have thin yet strong roots that can penetrate dense soils,¹⁹ like the many clayey subsoils found in South Carolina. The fibrous roots of grasses and some grains can access nutrients (especially phosphorus) deeper in the subsoils.¹³ When the CCs die, the nutrients are recycled back into the soil for subsequent crops to utilize.²⁰

Brassicas

Similar to grasses and grains, brassicas such as turnip (Brassica rapa), radish (Raphanus sativus), and canola (Brassica napus) can scavenge nitrogen.^11,21 These CCs have deep taproots that can reach nitrogen deep in the soil.²¹ The taproots of these plants also aid in reducing soil compaction and improving water and air movement as the roots create biopores when they decompose.²² Additionally, brassicas can function as trap crops, which can help reduce the presence of pests in the cash crop field.²³ Trap crops work by attracting pests and keeping the pests away from the cash crop.²⁴ For example, black mustard will attract the southern stick bug (Nezara viridula L.) away from corn, reducing kernel injury.²⁵ It is also important to note that CCs can also harbor pests that may interfere with and affect the subsequent cash crop.²⁶

Many brassicas, such as mustards (Brassica juncea), contain high levels of compounds called glucosinolates that naturally suppress soil pests,²⁷ soil-borne pathogens,²⁸ and diseases when released during the biofumigation process.²⁸ Biofumigation refers to growing brassica plants with high levels of glucosinolates, cutting the plants, and incorporating the biomass into the soil.²⁹ Decomposing plants release the biofumigant compounds, helping to suppress soil pathogens and diseases.²⁹ However, it is important to note that biofumigation is not always effective and is influenced by many variables, including the age of the plant, incorporation of the plant into the soil, soil moisture, and pest pressure.²⁷ The released biofumigant compounds are short-lived within the soil, inhibiting the growth of soil pests for about two weeks.²⁹

• Another way to group CCs is by their primary purpose.¹⁵ This method has four main groups: Catch crops, green manures, smother crops, and biofumigant crops.
• Catch crops: Catch crops are CCs that can efficiently scavenge and cycle nutrients, thus reducing nitrogen leaching.¹⁵ Examples include cereal rye (Secale cereale) and oats (Avena sativa).
• Green manures: Green manures are CCs that are excellent at providing nutrients, such as legumes.³⁰ Legumes create symbiotic relationships with bacteria in the root zone to fix atmospheric nitrogen to plant available forms.³⁰
• Smother crops: Smother crops are CCs that grow fast and shade out and out-compete weeds within a field.¹⁵
• Biofumigant crops: Biofumigant crops are CCs, such as brassicas, that release biofumigant compounds into the soil. These compounds can prevent weeds from germinating, emerging, and growing.¹⁵ Biofumigant compounds can also suppress microbial pathogens.²⁸

Many CCs fit into more than one group, as CCs can offer benefits in multiple ways. Refer to The Southern Cover Crop Council’s Cover Crop Resource Guide³¹ <https://southerncovercrops.org/cover-crop-resource-guide/row-crops/> to find commonly used CCs in South Carolina and their benefits.

Considerations

Improper selection and management of CCs can negatively impact cash crop production.⁸ To have a successful CC establishment and maximize the benefits of CCs within a field, the following variables are important to consider:

Desired benefits – One or More?

Identifying your desired benefit(s) is a crucial step when considering CCs. Common desired benefits from South Carolina farmers are preventing erosion, increasing soil fertility, alleviating soil compaction, suppressing pests, and suppressing weeds.

Preventing soil erosion

Cover crops can protect soil and reduce the risk of soil loss from water and wind erosion.⁶ Cover crops cover the soil (as live canopy and residues), limiting the soil’s exposure to wind and rain. Acting as a protective barrier from rain, CCs reduce the velocity of the raindrops that reach the soil. At a slower velocity, there is less force to dislodge soil particles, thereby less soil lost via water erosion. Additionally, the roots of CCs help to anchor the soil, reducing soil loss from wind erosion.⁶ When selecting CCs to prevent soil erosion, choose CCs that produce high biomass,⁶ have fast germination rates,⁶ have fine-branched roots.³² Examples include annual ryegrass (Lolium multiflorum), wheat (Triticum aestivum), barley (Hordeum vulgare), triticale (Secale cereale × Triticum aestivum) and oats.¹⁵ When soil erosion is a concern, planting a CC mixture is encouraged as CC mixtures can produce more canopy and greater biomass.³³

Increasing soil fertility

Cover crops can increase soil fertility through nutrient cycling of nitrogen and phosphorous for subsequent cash crops to utilize. Some studies show that CCs enhance soil microorganism populations within the soil as CCs are a carbon source and provide energy for microorganisms.³⁴ This includes microorganisms such as arbuscular mycorrhizal fungi, which are known to form a mutualistic relationship with plant roots, aiding in phosphorous cycling.³⁴ Additionally, CCs such as buckwheat can release acids into the soil, making phosphorous more soluble and thus easier for plants to uptake.³⁵

Legumes are essential CCs to boost plant-available nitrogen in the soil.¹⁵ Legumes can provide between 50 and 150 pounds of nitrogen per acre.³⁶ To achieve maximum nitrogen fixation, allow legumes to grow to reach the early flowering stage.¹⁵ Choosing species that can produce large amounts of biomass will also aid in reaching maximum levels of nitrogen fixation.¹⁵ Such species include hairy vetch (Vicia villosa), crimson clover (Trifolium incarnatum), red clover, and Austrian winter peas (Pisum sativum).¹⁵

Non-legume CCs cannot fix nitrogen.⁸ Grasses, in particular, can have the opposite effect and may tie up nitrogen within the soil, reducing the amount of nitrogen available to the subsequent cash crop.¹⁵ To prevent nitrogen tie-up when using grass CCs, grass CCs need to be terminated before maturity.¹⁵ If terminated early, grasses can aid in catching and cycling nutrients such as carbon.^15,19

Grasses, legumes, and brassicas can all be used as a “Catch crop” to reduce nitrate leaching.¹⁹ Catch crops take up nutrients, such as nitrogen, calcium and potassium,³⁵ that may be left over from the previous cash crop growing season that would otherwise be lost via erosion or deep percolation into the subsoil.³⁷ Cover crops also take up and use water, reducing the amount of water within the soil that is able to leach nitrate.³⁷ When the CCs are terminated and left in the field, nutrients, including nitrogen, phosphorous, and potassium are released to become available to the subsequent crop as the CCs decompose.³⁷ Termination timing is crucial to ensure optimal nutrient release rate and availability to the cash crop.³⁴ See the “Termination” section below for more information on termination methods and timing.

Alleviating Soil compaction

Soil compaction is a common problem on intensely cultivated lands.³⁸ When a field is plowed year after year, a compacted layer can develop right below the depth at which the soil was plowed.³⁹ Compacted soil is more dense with less pore space due to management activities that have rearranged soil particles and destroyed the soil aggregate structure.³⁸ For example, as heavy equipment is driven over a field, the soil particles are pushed closer together due to the weight of the equipment, reducing the space between soil particles and aggregates. Compacted soils can restrict water and air movement at the soil surface and within the soil,³⁸ resulting in increased runoff and erosion.⁴⁰ Compacted soils can also restrict crop root growth.⁴¹ With restricted root growth, the crops may have limited access to water and nutrients, resulting in reduced growth and yields.⁴¹

Some CC species can help alleviate compacted soil. The CC’s root architecture influences its ability to reduce soil compaction.¹⁹ Grasses have very fine, extensive root systems that are well-suited for reducing shallow compacted soils.¹⁹ Whereas CCs such as forage radish,⁴² and sunn hemp (Crotalaria juncea) ⁴⁰ can reduce deep compaction due to their durable tap roots.¹⁹ For example, tap-rooted CCs, including forage radish and canola, show benefits to growing maize in compacted soils.⁴¹ The tap roots of such plants can penetrate compacted subsoils, and when the plant is terminated and the roots decompose, the root channels, also known as bio-pores,²² can be used by subsequent cash crop roots to access water, nutrients, and air in the compacted subsoils.^41,22 Forage radish and canola can increase air permeability in compacted clayey soils.³⁸ See the “Soils and Climate” section for more information on tillage radish performance in South Carolina.

Suppressing pests

Different CCs can suppress a variety of pests. Both living CCs and CC residues in the field can provide a habitat for natural enemies and predators of pests.⁴³ The predators can interrupt pest and disease life cycles,^8,19 which can decrease the need for insecticides.⁴³ In a cotton field in Georgia, growing crimson clover and cereal rye as CCs and keeping the residues in the field after chemical termination reduced the number of thrip infestations.⁴³ Additionally, cereal rye can reduce boll injury on cotton from stink bugs and harbor higher densities of natural enemies than fallow fields.⁴³ Cover crops and CC residues can also interfere with a pest’s ability to reproduce and survive within a field by changing the host environment, including the olfactory and visual characteristics of the field.⁴⁴

As mentioned previously, brassica CCs release compounds that can suppress soil-borne pests within the soil due to their biofumigant properties.⁴⁵ As plants containing these compounds start to decompose, the compounds are released into the soil, helping to suppress soil pests, including fungi, nematodes, and weeds.⁴⁵

Suppressing weeds

While some CCs can control weeds through biofumigant properties, other CCs aid in weed suppression by out-competing weeds for resources such as water, sunlight, and nutrients.^6,8,19,46 When live CCs cover the soil surface, the CCs are exposed to and absorb red light, thereby reducing the amount of red light exposure available to weed seeds.⁴⁶ This decreases seed germination of the weeds within the soil.⁴⁶ Cover crop residues can also make nutrients unavailable to weeds as the CC residues can influence and change the nutrient cycle.⁶ A meta-analysis of 46 field studies revealed that using CCs for early-season weed suppression is comparable to management systems that use chemical and mechanical methods to control weeds.⁴⁷

Many studies have found a negative relationship between CC biomass and weed biomass.^46,48,49 Therefore, when selecting CCs to suppress weeds, choose CCs that establish quickly²⁶ and produce a high amount of biomass.⁴⁸ In other words, the higher the CC biomass, the greater the weed suppression. For example, increasing CC biomass up to 4126 lbs. acre^-1 suppressed weeds by almost 100% in a field where CCs were integrated into an oat and corn rotation.⁴⁸ Some studies have demonstrated that planting a CC mixture is more effective than planting one CC species for weed control.⁵⁰ Biomass is the driving factor in weed suppression.⁴⁸ Studies find that cereal rye is a CC that is very effective at suppressing weeds due to its fast establishment and high biomass.^48,51 However, it is important to note that there is such a thing as too much biomass. When CCs produce too much biomass, it can make it difficult to control, often adding cost to the additional termination methods that may need to be implemented to successfully terminate the CC.¹⁹ Snapp et al. (2005) suggest CCs above 30 cm in height produce too much biomass.¹⁹

Carbon/Nitrogen ratio

The carbon-to-nitrogen (C:N) ratio of CCs is another crucial consideration when selecting CCs. The C:N ratio directly influences the rate of CC decomposition and the subsequent release of nutrients from the CC residues.⁵² Cover crops with high C:N ratios (25:1 and higher) decompose slowly.⁵³ This slow decomposition rate can temporarily reduce the available nitrogen within the soil as the nitrogen is immobilized.⁵⁴ Immobilization occurs when microbes use available nitrogen in the soil to break down carbon-rich residues, making the nitrogen temporarily unavailable to the plants. In contrast, CCs with lower C:N ratios decompose faster. As the CC residues break down, the nitrogen is mineralized, meaning it becomes plant available.⁵⁴ Most legumes such as clovers, vetches and peas have a low C:N ratio, often below 20:1.⁵⁵ This makes legumes ideal for providing readily available nitrogen to the subsequent cash crop. On the other hand, most grains, with the exception of oats, have high C:N ratios.⁵⁵ Most grains’ high-carbon residues can help build soil organic matter but may require additional nitrogen inputs to prevent immobilization.

Timing

South Carolina has a temperate climate that is suitable for both winter and summer CCs.⁵⁶ It is necessary to understand the seasonality of the CC growth as different CCs grow and survive during different seasons.⁵⁷ For example, growing a summer CC that winter kills, such as sunflower (Helianthus annuus), may not be the best fit when trying to keep a field covered during the winter season. For more information on summer and winter CC species, visit The Southern Cover Crop Council Cover Crop Information Sheets³¹ <https://southerncovercrops.org/cover-crop-information-sheets/> and South Carolinas NRCS Cover Crop Guide⁵⁸ <https://richlandcountysc.gov/Portals/0/Departments/Conservation/DistrictDocs/EPW%20SC_CoverCrop_Species_Guide_9_1_2016.pdf>.

See tables 1 and 2 for CC options for summer and winter covers in South Carolina. Differences in climate across South Carolina mean there are different ideal planting times. Plant summer CCs between April 15 – June 1 in the Coastal Plain, May 1- June 15 in Piedmont, and May 15- June 15 in the Mountains.⁵⁸ Ideal planting dates for winter covers are split by type of cover: Plant grasses/grains and legumes between September 1- October 15 in the Coastal Plain, August 25 – October 1 in Piedmont, and July 25- September 15 in the Mountains.⁵⁸ Plant brassicas approximately two weeks earlier. Plant winter mixtures in the middle of the range between grasses/grains and legumes.⁵⁸

There are three primary methods to time CC planting within your crop rotation to achieve different goals:¹⁵

1. Use an entire growing season to grow a CC.¹⁵
2. Plant CCs between harvest and planting times of cash crops.¹⁵
3. Plant CCs into established cash crops, also known as interseeding.¹⁵

Use an entire growing season to grow CCs when a field has low fertility and or has been susceptible to erosion. This strategy helps build and accumulate organic matter within the field when no cash crops are planted that year.¹⁵ The most common time to plant CCs is between cash crop harvest and planting. Planting CCs during this period protects the soil from erosion and helps build organic matter before cash crop planting. Depending on what cash crop is grown, summer or winter CCs are suitable. In South Carolina, where the climate is mild, farmers can plant CCs right after harvesting cash crops. However, in other climatic zones across the United States where the winter is more extreme, there is a very short growing period for CCs, and CC establishment can be difficult. In these areas, farmers use interseeding techniques to plant CCs in fields where the cash crops are already established and growing.¹⁵ By interseeding CCs, farmers can establish a successful CC that otherwise would have been difficult.¹⁵ In South Carolina, studies show successful interseeding in corn without reducing corn performance.⁵⁹

The timing of termination is also a crucial management decision when using CCs.⁶⁰ Early termination of CCs can limit soil health benefits.⁶⁰ Ideally, CCs should be terminated late enough to produce a sufficient amount of biomass but early enough to prevent soil from drying out.⁶⁰ For example, in Alabama, a month’s delay in terminating rye and wheat CCs significantly increased biomass production.⁶¹ The increased biomass production can lead to greater carbon sources,⁶² enhanced soil microbial activity,⁶² reduced weeds,⁶³ and increased soil organic matter.⁶⁴ When the CCs are terminated, the CC residues help to reduce evaporation, keeping moisture in the soil.⁶⁵ However, terminating CCs too late may compromise soil moisture since actively growing CCs continue to use water from the soil.⁶⁰ Additionally, late CC termination in the southeast may interfere with cash crop planting and establishment due to the increased biomass.⁶⁰ For more information on termination timing, please visit Management Practices Affecting the Nutrient Provision Capacity of Cover Crops⁵⁵ <https://lgpress.clemson.edu/publication/management-practices-affecting-the-nutrient-provision-capacity-of-cover-crops/>.

Table 1. Common summer cover crops in the Southern United States suitable for South Carolina:

Table 2. Common winter cover crops in the Southern United States suitable for South Carolina:

Cover Crop Mixtures

Recently, interest has grown in using CC mixtures where multiple CC species are planted.⁶⁶ The driving force behind this practice lies in the fact that no single CC can provide all the benefits discussed.⁶⁶ For example, grasses such as cereal rye are great at adding biomass but lack the ability to fix nitrogen as legumes can. Therefore, depending on the desired benefits, a farmer may want to plant a CC mixture to enhance multi-functionality and offer a combination of benefits to a field.⁶⁶ When planting a CC mixture, keeping the seeding rate of aggressive growing species, such as grasses, at a low rate is crucial.⁶⁷ Less aggressive growing CCs such as oat, red clover (Trifolium pratense), forage radish and canola are typically kept at their monoculture seeding rates when included in a CC mixture.⁶⁸Doing so will help to prevent one species from becoming dominant, allowing other species in the mixture to grow and provide additional benefits.⁶⁷ However, it is important to acknowledge that CC mixtures do not always perform better than monocultures and can pose different challenges and concerns.⁶⁹ For example, establishing and terminating CC mixtures can be challenging as different species can finish their life cycle at different times.⁷⁰

Soils and Climate

Soil type and climatic factors influence CC performance.⁶ Therefore, tailor the CC selection to the field’s specific soil and climate conditions to ensure successful establishment and to maximize intended benefits. For instance, radish tap roots can help alleviate soil compaction.⁷¹ However, in South Carolina, the subsoils can be so dense that radish taproots are unable to penetrate the subsoil. Instead, they grow secondary roots that wrap around the primary tap root (figure 2).

Figure 2. Tillage radish pushes up out of the soil after reaching the clayey subsoil (a), tillage radish shows root deflection (b) (the pictures are not the same specimen). Images taken after cash crop desiccation. Keys provided as scale. Photo credit Calum Henderson.

To determine the soil composition and climatic type of a specific agricultural area, please use the USDA-NRCS Web Soil Survey (websoilsurvey.sc.egov.usda.gov). For more information on how to use the Web Soil Survey website, please refer to Native Plant Selection For Out-Of-Play Areas of South Carolina Golf Courses⁷² <https://lgpress.clemson.edu/publication/native-plant-selection-for-out-of-play-areas-of-south-carolina-golf-courses/>. The Web Soil Survey website provides information on climatic variables including the mean annual precipitation, mean annual air temperature, and the frost-free period. The Web Soil Survey also provides information on the soil composition, including the soil texture, drainage class, and available water supply.

Planting methods

There are many ways to plant CCs. Two common methods of planting CCs in South Carolina include drill seeding and broadcasting.^73,74 Each method has its own advantages and disadvantages.

Broadcast

Broadcast seeding refers to randomly spreading seeds over the seed bed manually or mechanically.⁷⁵ Tractor-mounted, PTO-driven cyclone spreaders broadcast seeds mechanically.⁷⁵

Advantages:

1. Less labor intensive as more area can be covered in less time compared to drill seeding.⁷⁴
2. Can allow farmers to plant CCs earlier than the alternative method of drilling.⁷³ As an interseeding practice, farmers may broadcast CCs while the cash crop is still in the field.⁷³

Disadvantages:

• Broadcasting can lead to uneven seed distribution.^74,75 Heavier seeds will fall closer to the broadcaster, while smaller/lighter seeds will land further away.
• Broadcasting depends on soil moisture for seed-to-soil contact which is essential for CC emergence. A dry field without cultivation practices may delay CC emergence.⁷⁴
• Broadcasting requires a higher seeding rate than drilling, increasing the cost of CC seeds.^73,74

Drill

Drill seeding refers to planting seeds at a controlled rate using a set of disks to cut an opening in the soil. Subsequently, the seeds are deposited into the soil opening, and the closing wheels pass over to cover and secure the seeds.⁷⁵

Advantage:

• Planting and covering the seeds in the soil helps to guarantee seed-to-soil contact, leading to a higher emergence and establishment rate of CCs compared to broadcasting.⁷⁴
• Lower seeding rates compared to broadcasting.⁷⁶
• Cover crops emerge earlier.⁷⁶

Disadvantages:

• Increased cost due to increased labor hours required for drill operations.⁷⁴ Drilling takes longer to complete compared to broadcasting.¹¹
• Time constraints as drilling cannot be accomplished if the soil conditions are too wet.⁷⁴ If the soil conditions are too wet, the farmer risks increasing soil compaction.⁷⁴

The average price of drilling CCs is $16.15/ per acre, while the average cost of broadcasting CCs is $12.40/per acre.^73,77 For more information on drill seeding, please refer to Grain Drills and Planters⁷⁸ <https://southerncovercrops.org/wp-content/uploads/2018/10/grain-drills-planters-2016.pdf>.

Termination

Cover crop termination is important as inadequately terminated CCs can reduce cash crop yields.^79,80,81 Cover crops are typically terminated in one of three ways: chemical methods, mechanical methods, or through winter kill.⁸² Farmers can use more than one termination technique at a time. For example, it is a common method to supplement mechanical termination with a herbicide to terminate CCs.⁸³ The method used to terminate CCs will depend on the CC species and the growth stage of the CC.⁸²

Chemical

Terminating CCs through chemical means is the most practiced termination method and involves spraying CCs with a herbicide.^82,84 This can occur before or after cash crop planting.⁸² The herbicide(s) used to terminate the CCs will depend on the CC species. For example, when terminating red clover, glyphosate alone may not be effective, and therefore, dicamba may also be used.⁸⁵ For more information on what herbicides are most effective for specific CCs, visit Termination with Herbicides⁸⁵ <https://southerncovercrops.org/cover-crop-resource-guide/row-crops/coastal-plain/terminating-cover-crops/how-should-i-terminate-my-cover-crop/termination-with-herbicides/#:~:text=The%20use%20of%20selective%20herbicides,control%20of%20legume%20cover%20crops>.

Mechanical

Mechanical termination stops CC growth by rolling, rolling-crimping, roll-chopping, undercutting, or mowing.⁸² When using mechanical methods, it is important to pay close attention to the growth stage of the CC. Improper timing may require the addition of an herbicide to terminate the CC effectively. Additionally, some CCs, such as clovers and canola, are difficult to kill through mechanical methods and may require multiple passes or herbicides.⁸⁶ For more information on mechanical termination, visit Termination with Rolling and Crimping⁸⁶ <https://southerncovercrops.org/cover-crop-resource-guide/row-crops/coastal-plain/terminating-cover-crops/how-should-i-terminate-my-cover-crop/termination-with-rolling-and-crimping/> and Managing Cover Crops Profitably³⁵ <https://www.sare.org/wp-content/uploads/Managing-Cover-Crops-Profitably.pdf>.

Winter Kill

Winter kill allows frost or freezing conditions to terminate the CCs.⁸² Some cool season CCs such as oats, radishes, and other brassicas ⁸⁷ are not as winter hardy and most summer CCs reliably frost kill. Winter kill depends on temperature conditions.⁸² For example, in some regions of SC, such as the Southern Coastal Plains, the temperature may not get low enough for a long enough duration for winter kill to be an effective or manageable option.⁸⁷ Please refer to the Southern Cover Crop Council guides for winterkill as an option in the area of interest⁸⁷ <https://southerncovercrops.org/cover-crop-resource-guide/row-crops/mountains-ridge-valley-piedmont/terminating-cover-crops/how-should-i-terminate-my-cover-crop/winter-or-frost-kill/>.

Cost Incentives

A few cost incentive programs are available in South Carolina for using CCs. One of the major programs is the Environmental Quality Incentives Program (EQIP) offered by the Natural Resource Conservation Service (NRCS). The EQIP program provides technical and financial assistance to farmers and landowners when conservation practices, such as cover cropping, are adopted to help tackle environmental concerns.⁸⁸ Environmental concerns of interest include soil health, soil erosion, air quality, water quality and reliance to extreme weather events.⁸⁸ The amount EQIP will pay a farmer or landowner per acre that is cover cropped varies but typically ranges between $34-$75.⁸⁹ The EQIP program for providing cost incentives for adopting CCs generally last three years.⁸⁹ For more information on the EQIP program, please visit The Environmental Quality Incentives Program⁸⁸ <https://www.nrcs.usda.gov/programs-initiatives/eqip-environmental-quality-incentives>.

Another cost incentive program to be aware of is the Conservation Stewardship Program (CSP), also offered by NRCS. Similar to the EQIP program, the CSP program offers technical and financial assistance when conservation practices are adopted.⁹⁰ The main difference between the two incentive programs is that CSP is geared more toward long-term goals, as CSP contracts usually last 5 years and cover the farmer’s entire operation.⁹⁰ With the CSP program, farmers must demonstrate that they have previously been implementing conservation practices but are ready to enhance and improve their efforts and/or add additional conservation practices to their operation.⁹⁰ For more information on the CSP program, please visit The Conservation Stewardship Program⁹⁰ <https://www.nrcs.usda.gov/programs-initiatives/csp-conservation-stewardship-program>.

Resource availability

Knowing what resources are available is essential to consider when using CCs. The Southern Cover Crops Council has an easy-to-use tool to determine a specific agricultural area’s soil composition and climate type. The tool can be accessed here: <https://covercrop-selector.org/>. This tool can help identify proper CC selection for the given field, CC growing window, and desired benefits. To find information on seed sources, please visit Seed Sources <https://southerncovercrops.org/cover-crop-resource-guide/seed-sources/> and Mixon Seed Service <https://mixonseed.com/cover-crops/>. For general information on CCs, please visit Cover Crops for Sustainable Crop Rotations <https://www.sare.org/resources/cover-crops/>.

Summary

Cover crops can provide numerous in-field benefits as well as ecosystem benefits when integrated effectively. To ensure proper integration of CCs, consider several factors: the intended benefits, the growing period for CCs, the soil and climate conditions of the field, and the method of planting and terminating the CC. Consulting resources, including nonprofit organizations like the Southern Cover Crop Council and Southern SARE, as well as NRCS and Extension Service personnel, can assist in addressing the considerations and making informed management decisions regarding CCs.

References Cited

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