Cover crops: the dos and the don’ts

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.

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

Don’t

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.

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:

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.

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.

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.