Catch crops and cover crops guide

In recent years, we have seen renewed interest in the use of catch crops in Ireland. Also known as cover crops or green manure, catch crops have a role to play in the regulatory requirements for green cover under the Agri-Climate Rural Environment Scheme (ACRES) rules.

The increased interest is driven by farmers’ desire to use them to improve crop productivity and soil structure. There are different options available in terms of the species or mixtures that can be used as catch crops.

In this guide, we aim to explain the requirements under ACRES and examine the benefits of growing catch crops. We also explore the suitability of various ACRES cover crops and mixture options for different requirements.

Contents

1. The benefits of catch crops
2. ACRES scheme options
3. Catch crop mixtures
4. Catch crops examples
5. Management of catch crops

The benefits of catch crops

Catch crops are planted to reduce nutrient leaching from the soil following the main crop. The crop then scavenges available nitrogen and other nutrients.

Cover crops are grown to provide “green” cover to the soil. Cover crops will help prevent soil erosion while also suppressing weeds. Some cover crops can also reduce the incidence of pests and diseases.

Green manure crops are those that are sown into the soil to improve and condition it, while also releasing nutrients. In this guide, we will refer to all of these as catch crops.

Why grow catch crops?

• To comply with ACRES scheme
• Prevent nutrient leaching
• Encourage nitrogen fixation
• Reduce soil erosion
• Produce forage for livestock
• Soil conditioning
• Improve soil organic matter
• Improve drainage
• Control pests and diseases
• Control nematodes

ACRES scheme options

Catch crops are an important part of both the ACRES scheme – please click on the link for further information.

Catch crop requirements

The objective within ACRES is ‘to establish a catch crop that will reduce nutrient leaching and help prevent soil erosion in the autumn/winter period’.

• Establish the catch crop using non-inversion cultivation methods (no ploughing).
• The crop must be sown before 15th September each year using certified seed.
• The catch crop must remain in situ from the date of sowing to 1st January annually.
  
  • After January 1st, light grazing or incorporation is permitted.
  • Do not graze where soil erosion is a risk, intensive strip grazing/ zero grazing is not permitted.
  • If grazing, there must be an adequate lie-back area always accessible to livestock, in accordance with GAEC 6 Conditionality Rule.
• When sowing the catch crop, under sowing or sowing of a grass crop is not permitted.
• A main cereal crop may not be under sown with a catch crop species. The seed mix must comprise at least two species using the monoculture seed rates from the prescribed list:
  
  • There is no maximum in terms of the number of species that can be used, but at least 100% of a full sowing rate must be reached.
  • You must not have any more than one species at 60% of a full sowing rate in the mix.

The following is the list of prescribed catch crops and cover crops permitted in the ACRES scheme and the sowing rates.

Catch crop mixtures

Regardless of whether or not you are participating in the ACRES scheme, catch crops offer multiple benefits to improve soil condition in arable situations.

At Germinal, we have designed a range of catch and cover crop mixtures to comply with ACRES rules, while also bringing multiple benefits to your soil.

When sowing catch or cover crops, it is important to remember:

• Sow as early as possible (prior to 15 September for ACRES scheme requirements)
• Ensure you select from the list of prescribed crops
• If you have a brassica in your arable rotation (e.g. oilseed rape), do not use a mixture containing a brassica
• Do not allow crops to set seed (weeds in future crops)

We recommend you select one of our SoilBooster mixtures when sowing your crop.

Soil Booster Graze (2 ha pack)

16 kg: 8.00kg forage rape; 8.00kg leafy turnip

Soil Booster Graze will rapidly establish green cover while reducing nutrient leaching and condition the soil by improving drainage, aeration, and reducing erosion.

Provides a valuable high-energy feed for winter growth with cattle or sheep.

Key benefits

• Rapid growth
• Soil conditioning
• Improves soil structure
• Reduces nutrient leaching
• Suppress weeds
• Suitable for grazing after 1 January

Soil Booster Gold (1ha pack)

2.00kg: Tillage radish; 1.00kg forage rape; 2.00kg: mustard; 2.00kg linseed; 2.00kg phacelia; 4.00kg vetch; 2.00kg crimson clover

Soil Booster Gold is a catch crop mixture offering a wide variety of benefits due to the diverse nature of the species included.

It will aid in water infiltration helping drainage along with suppressing weeds due to the potential to produce a large amount of biomass in a short window.

Key benefits

• Nitrogen fixing
• Organic matter
• Suppress weeds
• Reduce nutrient leaching
• Biomass production
• Soil conditioning
• Improved drainage
• Diverse mixture of species

Soil Booster Non-Brassica Grazer (0.5ha pack, OSR friendly)

4.00kg: Vetch; 0.60kg phacelia; 3.25kg crimson clover; 11.65kg forage rye

Soil Booster Non-Brassica Grazer is a grazing option where oilseed rape is included in the rotation, providing rapidly growing cover that can fix nitrogen. It is also suited where the risk of clubroot is of concern.

Key benefits

• Nitrogen fixing
• Can be grazed
• Suppress weeds
• Suits rotations with oilseed rape
• Reduced nutrient leaching
• Nutrient scavenging

Soil Booster Pro (1ha pack, OSR friendly)

16.8 kg: 12.00kg vetch; 4.80kg phacelia

Soil Booster Pro is a quick-establishing mixture that will produce a canopy and outcompete weeds. Vetch will fix nitrogen and, with good frost tolerance, will maintain a canopy over winter.

Phacelia has both a fibrous root system and a taproot that will improve soil structure. An ideal option where oilseed rape is in the rotation.

Key benefits

• Fast establishment
• Nitrogen fixing
• Improves soil structure
• Suited to rotations containing oilseed rape
• Suppress weeds

Catch crops straights

Cover crops bring a range of benefits to the soil and subsequent crop. Choosing the ideal species to meet your requirements will unlock the most benefits for your farming system.

The following range of cover crops will achieve various degrees of biomass accumulation while also bringing additional benefits:

• Reduced nutrient loss
• Improving soil structure
• Prevention of soil erosion
• Improving organic matter
• Reduced disease, pests and weeds
• N fixation and a potential forage source

Our cover crop mixtures are designed specifically for Irish farm situations. Coming up is a summary of the key benefits for each species, including details on frost tolerance, disease and pest resistance, and ability to
produce biomass.

Forage rape

This can be grazed after 1 December as a forage for cattle or sheep. Rapid growing ability with good winter hardiness, Forage rape is a high-energy feed for grazing ruminants.

• Sowing rate: 8kg/ha
• Frost tolerance: Good
• Biomass: Good
• Pests and diseases: Generally, not a problem, but clubroot could become an issue if brassicas are used as a cover crop over a period of years

Tillage radish

A deep-rooting plant that extracts nutrients from down in the profile and helps open channels in the soil for subsequent crops. Tillage radish improves water movement and drainage and increases airflow through the soil.

• Sowing rate: 10kg/ha
• Frost tolerance: Poor – frost will help decay tillage radish and thus avoid the requirement for chemical spray
• Biomass: Will generate large biomass quickly
• Pests and diseases: Generally, not a problem, but clubroot could become an issue if brassicas are used as a cover crop over a period of years

Mustard

Mustard is a rapidly growing annual that will help reduce nitrogen leaching and suppress weeds.

• Sowing rate: white - 15kg/ha; brown 7kg/ha
• Frost tolerance: Low, but this helps in its incorporation as it will be largely diminished over
• the winter
• Biomass: Good
• Pests and diseases: Generally, not a problem, but clubroot might become an issue if brassicas are used as a cover crop over a period of years

Leafy turnip

Leafy turnip is a member of the brassica family with high early vigour. Their deep rooting will help condition the soil and relocate nutrients from the subsoil to the top. It will also help reduce nitrogen leaching.

• Sowing rate: 8kg/ha
• Frost tolerance: Good
• Biomass: Yields of 3-5 t DM, suitable as a forage crop
• Pests and diseases: Generally, not a problem for a leafy turnip, but clubroot could become an issue if brassica is used as a cover crop over a period of years

Oats and Black oats

Oats and black oats can provide cover over the winter to help reduce soil erosion due to good tillering capacity. Oats have poor winter tolerance and are easily killed and worked back into the soil. Useful for weed suppression and as a nurse crop with hairy vetch.

• Sowing rate: oats - 100kg/ha; black oats - 60kg/ha
• Frost tolerance: Poor
• Biomass: Reasonable
• Pests and diseases: Generally, not a problem

Peas

Peas have good nitrogen fixation abilities and can be sown as a nitrogen-fixing crop in an area declared as an EFA. Generally, peas are not suited for sowing after a main cereal crop as it is too late in the season for them to establish.

• Sowing rate: 20kg/ha
• Frost tolerance: Poor
• Biomass: Good if sown early in the season
• Pests and diseases: Generally, not a problem

Beans

Beans, like peas, have excellent nitrogen fixation abilities and can be sown as a nitrogen-fixing crop in an area declared as an EFA. Beans are not suited for sowing after the main cereal crop as it will be too late in the season for them to establish.

• Sowing rate: 140kg/ha
• Frost tolerance: Poor
• Biomass: Good if sown early in the season
• Pests and diseases: Generally, not a problem

Hairy vetch

Hairy vetch, a forage legume also known as Winter vetch, has superior winter hardiness over Common vetch and is very suitable for sowing as a cover crop due to its ability to fix nitrogen at lower temperatures than many other legumes.

This can also be used as arable silage with grass or as a whole crop mix combined with cereals. Vetch will help increase the protein content in the mix.

• Sowing rate: 30kg/ha
• Frost tolerance: Good winter hardiness
• Biomass: Rapidly produces a large biomass
• Pests and diseases: Generally, not a problem

Common vetch

Common vetch is suitable for sowing as a cover crop because of its ability to fix nitrogen and suppress weeds due to its ability to rapidly form a canopy.

• Sowing rate: 30kg/ha
• Frost tolerance: Good winter hardiness
• Biomass: Rapidly produces a large biomass
• Pests and diseases: Generally, not a problem

Forage rye

Extensive and deep rooting, forage rye is excellent for soil conditioning. Effective at reducing nitrogen leaching and soil erosion over the winter.

Forage rye is also suitable for grazing in early spring. It provides a flexible sowing option after maize/cereals and can be grazed or zero grazed.

• Sowing rate: 150kg/ha
• Frost tolerance: Good winter hardiness
• Biomass: Good
• Pests and diseases: Monitor at establishment for leatherjackets, slugs and frit-fly. Generally, not a problem once established

Crimson clover

Clovers have excellent capability to fix nitrogen at soil temperatures above 8°C but are less effective over the winter period.

Crimson clover is suited to earlier sowing in July/August to maximise warmer temperatures. Quicker to establish than longer-term clovers. Ideal for usage as green manure for soil improvement.

• Sowing rate: 15kg/ha
• Frost tolerance: Good
• Biomass: Good
• Pests and diseases: Monitor at establishment for leatherjackets, slugs and frit-fly. Generally, not a problem once established

Berseem clover

This short-term annual legume is referred to as Egyptian clover. It can establish quickly and produce biomass when sown at suitable temperatures.

Berseem clover can be used as soil-improving green manure. Some work has shown that it can be used as a companion crop in oilseed rape.

• Sowing rate: 15kg/ha
• Frost tolerance: Sensitive to Frost
• Biomass: High biomass potential
• Pests and diseases: Generally, not a problem

Red clover

Red clover is primarily used in grass and forage mixtures but can also be sown as a cover crop.

This winter hardy crop offers several benefits, including fixing nitrogen to meet the needs of the following crop, protecting soil from erosion over winter, improving water infiltration and alleviating compaction as red clover produces a deep taproot.

When destroyed, it’s an excellent green manure. Red clover also attracts beneficial insects while growing.

• Sowing rate: 20kg/ha
• Frost tolerance: Good
• Biomass: Good if sown early in the season
• Pests and diseases: Root rot and fungal diseases if sown in soil with inadequate drainage

Squarrosa clover

This annual clover can withstand temperatures of -10°C at its rosette stage. Squarrosa clover grows upright with a thin taproot and many branches. It can produce a lot of organic matter and is good for soil structure.

• Sowing rate: 15kg/ha
• Frost tolerance: Very winter-hardy
• Biomass: High biomass potential
• Pests and diseases: Generally, not a problem

Balansa clover

This is an annual clover noted for its winter hardiness when compared to other annual species such as Egyptian and Persian clovers.

Balansa clover can establish quickly and produce biomass when sown in suitable warm conditions, much like the other annual clovers. Balansa clover has unique top growth along with a large taproot, making it a species option worth looking at.

• Sowing rate: 15kg/ha
• Frost tolerance: Very winter hardy
• Biomass: High biomass potential
• Pests and diseases: Generally, not a problem

Phacelia

Phacelia is a rapidly growing crop, which will reduce nitrogen leaching and suppress weeds, with a beneficial root structure.

• Sowing rate: 8kg/ha
• Frost tolerance: Poor
• Biomass: Lower biomass than many other cover crops, but it works extremely well as part of a mixture and the recommendation would be to sow it with other crops
• Pests and diseases: Generally, not a problem

Buckwheat

Establishing quickly and helping suppress weeds, buckwheat is a fast-growing crop which will help reduce nitrogen losses.

Buckwheat is good to scavenge phosphate in the soil, which it can make available for subsequent crops after incorporation.

• Sowing rate: 50kg/ha
• Frost tolerance: Poor
• Biomass: Good
• Pests and diseases: Generally, not a problem

Austrian Winter Pea

Peas have good nitrogen fixation abilities and can be sown as a cover crop after a main cereal crop, but need to be sown as early as possible post-harvest to maximise growing temperatures.

Austrian Winter peas are a species that can withstand lower temperatures and produce more biomass over winter.

• Sowing rate: 80kg/ha
• Frost tolerance: Good
• Biomass: Good if sown early in the season
• Pests and diseases: Generally, not a problem

Linseed

Linseed is a thin upright plant that establishes easily, developing a deep fibrous root that has the ability to condition soil to depth.

• Sowing rate: 30kg/ha
• Frost tolerance: Poor but will stand through winter
• Biomass: Lower biomass than other cover crops
• Pests and diseases: Generally, not a problem

Safflower (not ACRES approved)

Safflower belongs to the family Compositae and is widely grown as a catch crop and green manure across Europe. It can establish quite quickly and has an extensive rooting structure, penetrating up to 2.5 m of soil depth. The main advantage of safflower is its drought resistance and rapid growth once sown.

Sowing rate: 3kg/ha

Frost tolerance: Poor

Biomass: Lower biomass than many other cover crops, but it works well as part of a mixture and the recommendation would be to sow it with other cover crops.

Pests and diseases: Generally, not a problem

Sunflower

Sunflowers have a robust root system enabling them to scavenge nutrients and are also good for mycorrhizal fungi growth in the soil.

They are best sown early after harvest, developing a deep taproot which helps them penetrate layers within the soil and alleviate compaction. The sunflower produces a beautiful flower, attracting pollinators and supporting biodiversity.

Sowing rate: 20kg/ha

Frost tolerance: Good

Biomass: Good if sown early in the season

Pests and diseases: Generally not a problem as a cover crop

Smart Radish

A new radish bred in New Zealand specifically for the cover crop and soil health market. Smart Radish® is the first true cover crop radish designed for nutrient scavenging.

It produces a strong taproot to break compaction and a mass of lateral roots to take up nutrients, while also offering clubroot resistance and bio-fumigant properties.

Sowing rate: 4-6 kg/ha

Frost tolerance: Poor. Frost helps decay tillage radish and thus avoids the requirement for chemical spray

Biomass: Generates biomass quickly

Pests and diseases: This radish is clubroot-resistant and suitable for all mixtures

Management of catch crops

Rapid establishment of catch crops following harvest will ensure there is adequate moisture for germination before stubbles dry out from lack of cropping cover.

When to sow

Spring or autumn are the best times to grow catch crops. In autumn, the earlier they can be established the better, to make use of longer days and warmer ground temperatures. Every day counts once the cereal crop is harvested.

How to sow a catch crop

Drilling a catch crop as soon as possible after the cereal harvest keeps the soil active all the time. The leaching of nitrogen is minimised and the organic matter that will be incorporated into the upper soil is maximised. Crops can be drilled directly into stubble or broadcast onto cultivated ground.

Since all mixes contain a combination of small and big seeds, a sowing depth of 1.5-3 cm is recommended. Rolling is important to ensure good soil-to-seed contact and help maintain soil moisture for germination and growth.

Fertiliser

Farmyard manure/compound fertiliser could be applied prior to cultivation/drilling to provide the growing plants’ basic nutrients. This will maximise growth and subsequent biomass for grazing or cover for overwintered crops.

Nutrients applied will be taken up by the growing catch crop and released upon breakdown in the spring to the following cash crop. Where sown as a Greening requirement, minimal fertiliser if any is recommended.

However, if intending to graze the crop, applications of nitrogen and phosphate are essential to increase yield.

Incorporation of crops

Generally, temperatures over winter in Ireland are not low enough to kill the crop, so it is recommended to burn them off with herbicide or cut with a flail mower.

Incorporation can then be done by ploughing or rotavating. After burning off, the catch crop can be incorporated by discing and the cash crop can be drilled in.

Find the best catch and cover crops for your system

You can ask your local seed merchant for Germinal's catch crop varieties and mixtures. Or feel free to speak with one of our forage crop experts to discuss your requirements.

Niall Laffan, Area Sales Manager, South/Southwest

T: 085 841 6477

E: [email protected]

Diarmuid Murphy, Area Sales Manager, Southeast/Midlands/West

T: 085 747 3865

E: [email protected]

Claire Bailey Archibald, Area Sales Manager, Northeast

T: 087 470 6908

E: [email protected]