Winter Cover Crops: Enhancing Soil Health and Management

Typically grown during the winter months to cover bare soil and stubble, preventing soil erosion, cover crops play an essential role in enriching the soil and improving soil structure on arable land.

Our guide below outlines how to effectively use cover crops for winter soil enrichment across arable systems.

Why use cover crops?

Using cover crops offers a range of advantages to your soil, especially during the harsh winter months. These include:

• Soil fertility: Many cover crops, especially legumes, can fix nitrogen from the atmosphere into the ground, enriching the soil.
• Erosion prevention: Cover crops form a protective barrier, minimising the impacts of rain and wind on exposed soils.
• Weed suppression: A dense cover crop mix can inhibit the growth of unwanted weeds.
• Improved soil structure: The root systems of cover crops can break up compacted soil layers and improve water infiltration.
• Organic matter: As cover crops decay, they contribute organic matter to the soil, improving its fertility.

Choosing the right cover crop

Depending on your goals and the specific needs of your soil, the selection of the right cover crop is crucial.

These commonly used cover crops can provide particular soil benefits.

Legumes:

• Hairy Vetch: This is an excellent nitrogen fixer and can survive cold winters.
• Field Peas: These also fix nitrogen and do well in cooler temperatures.
• Clovers (crimson, red, and white): They fix nitrogen and can be incorporated into the soil in spring.

Non-Legumes:

• Rye (Cereal Rye): It’s an aggressive grower, can suppress weeds, and its deep roots help in soil loosening.
• Oats: They winter-kill in colder climates but can provide good biomass.
• Winter Wheat: This can survive many winters and is known for its dense root system.

Planting cover crops

To maximise the benefits of your chosen cover crops, planting techniques should be carefully considered.

Each stage of the planting process makes a contribution to the success and performance of your cover crops, so a well thought-out planting plan is essential.

1. Preparing the land: Before planting, it’s crucial to remove previous crops and weeds from the field to prevent diseases and pests from lingering.

It’s also beneficial to test the soil to determine its pH and nutrient content, which can help in selecting the most beneficial cover crops and determining if soil amendments are necessary.

Depending on the farming approach, some farmers may lightly till the soil to create a smooth seedbed, improving seed-to-soil contact, while others may opt for no-till systems to help preserve soil structure.

1. Sowing: When it comes to sowing, broadcasting seeds helps to cover large areas quickly, while drilling them instead can offer more precise spacing and depth.

Precision drilling is advantageous for grasses such as cereal rye and winter wheat, which have smaller seeds. Whereas legumes like hairy vetch and field seeds have larger seeds so need to be sown at depth.

1. Watering: During the initial weeks post-sowing, it’s essential to monitor the soil’s moisture levels, adjusting watering practices based on both rainfall and the soil’s conditions to ensure the young plants thrive.

Managing cover crops

Once established, cover crops require careful management to ensure they fulfil their intended roles without becoming a nuisance.

• Mowing: If your cover crop begins to flower and you want to prevent it from seeding, mow it.

Mowing not only prevents unwanted seeding but also helps in returning organic matter back to the soil, as the mowed plants decompose.

• Mixtures: Instead of relying on a single type of cover crop, consider planting a diverse mixture of both legumes and non-legumes.

This multi-species approach offers several advantages. Including legumes, such as clover, have the unique ability to fix atmospheric nitrogen, thereby enriching the soil.

Non-legumes, on the other hand, like rye or oats, can contribute to improved soil structure by reducing soil compaction and enhancing water infiltration.

• Avoiding Pests: Some cover crops can attract pests or host specific diseases. Rotate your cover crops periodically to avoid buildup and disrupt the life cycle of pests and diseases.

Terminating cover crops

As winter ends and you prepare for the next planting season, it’s essential to know how to effectively terminate or incorporate your cover crops.

1. Winter-kill: Some cover crops, such as oats, are not frost-hardy and naturally die off during severe winter conditions. This natural process is referred to as winter-kill.

When spring arrives, these crops have already begun to decompose, making the fields easier to manage.

The dead vegetation from these crops serves as a protective mulch on the soil surface, reducing erosion and helping retain moisture.

1. Mowing or crimping: For more resilient cover crops that survive the winter months, mowing is an effective method for termination.

Mowing cuts down the crops, but for a more lasting effect, a roller crimper can be used. This tool crimps or crushes the stems of the cover crops, hindering their ability to regrow.

1. Tilling: Tilling or ploughing under the cover crops is a traditional method to incorporate them into the soil.

This allows for faster decomposition of the plant material, which in turn releases the stored nutrients back into the soil.

This can be particularly beneficial for enriching the soil in preparation for the subsequent planting season. Do this a few weeks before planting your primary crop.

1. Herbicides: In situations where mechanical methods might be ineffective, impractical, or time-consuming, the application of specific herbicides can provide a solution.

Conclusion

In conclusion, cover crops are an indispensable tool for sustainable agriculture, ensuring the soil remains healthy and productive in between cash crops.

By embracing cover crop benefits and optimal management techniques, farmers can greatly improve the quality of their soil and primary crops yields.