It’s a difficult season for tillage farmers. Weather has not played ball and has impacted crop yields. Grain prices are also back significantly, so finances are a worry for many.

Cover crops become a difficult decision for some then. If you are using cover crops as a measure in the Agri-Climate Rural Environment Scheme (ACRES), then you have to plant them, but if you are doing it voluntarily the decision becomes more difficult in a year where finances are tight.

The long-term benefits of cover crops need to be considered. There may be a patch of land that struggled this season as it held water.

Maybe it was compacted and would benefit from a tap root to break up the ground. In the short term they will cover the soil and take up nutrients, which may otherwise be lost to water.

If you are planting cover crops, you need to get the best out of them. Cover crops should ideally be planted after winter barley or oats to get them into the ground early and off to a good start.

Phacelia has small roots and can help make the soil crumbly. Its pictured at the Seedtech open day.

A day in July is worth a week in August and a month in September when it comes to growing cover crops.

The earlier you plant them the more the crop should grow meaning more forage for grazing animals, or organic matter for the soil, bigger roots, more nutrient uptake, as well as a good habitat for beneficial insects.

The do’s and don’ts of cover crops

Do

  • Plant early.
  • Choose a variety that suits your farm.
  • Choose a competitively priced seed mix.
  • Use Department of Agriculture labelled seed with a HVS sticker.
  • Make sure your seed meets ACRES specifications.
  • Apply buffers and lie-backs where grazing is going to be carried out.

    • Don’t

  • Use imported seed which has not been tested for grass weeds.
  • Grow Brassica cover crops where there is oilseed rape in the rotation.
  • Cultivate and plant cover crops in wet conditions.
  • Plant a 14-way mix of seeds if you’re new to cover crops, start small.
  • Graze before 1 January if you are in ACRES.

    • Grazing cover crops

    Remember last year saw new rules brought in for farmers grazing cover crops. Good agricultural and environmental conditions GAEC 4 under the Common Agricultural Policy (CAP) seeks to protect soil quality. Farmers are struggling to see the logic behind these rules. They are making it difficult for livestock and tillage farmers to work together to graze these crops while showing little evidence of benefit to soil or water quality.

    Forage rape has a deep tap root which can help to break compacted soil. It can also produce large amounts of forage for grazing.

    The benefits of tillage and livestock farmers working together to recycle nutrients and improve soil health seem to be somewhat lost in the rules.

    However, they still have to be complied with.

    You must:

  • Leave a 3m buffer around the perimeter of the field. This should be cultivated, but not planted.
  • The 3m uncultivated buffer at a watercourse should be extended by 1m, which can be cultivated to generate volunteers.
  • The watercourse should be fenced to 1.5m where the farm’s stocking rate is over 170kg N/ha.
  • 30% of the area for grazing should be a lie-back of either grass or cultivated stubbles.

    • Seed mixes

    Under ACRES requirements, farmers must plant by 15 September and plant at least two species from the list in table 1. The minimum seed rate must be adhered to for at least two species.

    The minimum seed rate is the lower rate for each species outlined in the table. For any other species the grower can use the rate they deem appropriate.

    Leafy turnip has a good tap root and is ideal for grazing.

    Many merchants and co-ops will have premixed bags of cover crop seeds. Some of these will be suitable for grazing, others will be aimed at improving soil health.

    Club root

    If you are growing oilseed rape, you only grow it once every five or six years in the same field. This is to reduce the risk of disease and club root in particular. Club root affects Brassica crops. Therefore, it can also affect and be carried by catch crops like forage rape, tillage radish and mustard.

    Vegetables like cabbage and Brussel sprouts can also be affected and weeds like charlock and shepherd’s purse. Volunteer rape will also carry the disease.

    In recent years, incidences of club root have become more common and some of these cases are linked to Brassica catch crops being grown in fields between oilseed rape crops.

    For that reason, you should avoid Brassica plants in your catch crop mix where you are growing oilseed rape. This should help to reduce the risk of clubroot in crops.

    A mix of cover crops including phacelia, forage rape, vetch, tillage radish, leafy turnip and forage rape.

    Plants affected by clubroot will struggle to grow, as their root will not make its way down into the soil like other plants and can be swollen. There will be fewer fine roots on the plant and the roots can look distorted.

    Labelled seed

    When planting cover crops, there is a big risk of importing a weed problem onto your farm. Most of the seed is imported. For this reason, it is essential that you purchase the highest standard seed possible.

    The Irish Seed Trade Association (ISTA) has implemented a higher voluntary standard for cover crop seed. Members of the Association have voluntarily decided they want to test their cover crop seed for grass weeds and label it so that farmers will know it has been tested for blackgrass, wild oats and sterile brome.

    This seed will carry the Department’s green label with the mixture outlined on it and will also have an ISTA sticker to say that it has been tested for grass weeds.

    Purchasing seed which has been tested for weeds is a must and a simple way of reducing grass weed risks on your farm.

    You can see the sticker in Figure 1.

    Figure 1. The ISTA higher voluntary standard label and stickers for cover crop seed.