Cover Crops & Companion Crops

Cover Crops & Companion Crops

‘Cover Crops & Companion Crops –  My Top Ten Tips’

by Thomas Fouhy

  1. Select fast growing cover crops for Autumn planting which tend to trap more available N and other nutrients. (Varieties such as Oats, Black Oats , Rye, Triticale, Westerwolds Rye Grass are suitable).
  2. Nitrogen fixing crops such as clovers, vetches, legumes work better as companion crops as they are planted in the correct growing season where Nitrogen fixation can take place when soil temperatures are above 12 degrees C.
  3. Use Brassicas only in a cover crop mix because they are a non-mycorrhizal host, as a monocrop they can depress soil microbiology.
  4. Try to avoid planting the same variety in a cover crop as the following cash crop as this can lead to disease issues.
  5. Never plant a companion crop that will compete with the cash crop for sunlight and nutrients.
  6. Terminate cover crops properly as they may become a weed in the following cash crop .
  7. Apply farmyard manure to cover crops in the Autumn as they will make the Nutrients more available in the Spring to the following cash crop.
  8. The more diverse the cover crop and companion crop mix is the greater the potential to mine and cycle nutrients for the following cash crop .
  9. Sow Autumn Green cover as soon as possible , to avail of warm soils and warm day time temperatures (i.e. late August, early September).
  10. Each action on its own will achieve benefits across the rotation but the combination of cover crops and companion crops together can have dramatic effects on the cash crops in the rotation.

 About Thomas Fouhy

Thomas is an organic, min-till, stockless, arable farmer with 84 acres in north Co. Cork. Apart from the many trees and hedgerows on his land, he proactively farms all available ground. Nature takes advantage of how well he manages the delicate balance of building and maintaining soil health. Thomas crops on a 10-year flexible rotation that includes speciality crops like grain-lupins, linseed, lentils, sunflowers, as well as the standard grain crops. He has 10 acres of just flowers! He demonstrates the breadth of largely unexplored crops we can produce in Ireland and highlights our potential to produce our own protein crops, reducing our reliance on imported soy. The soil is never bare for long, crops are under-sown with red clover, and diverse winter cover-crop mixes fill the gaps between the cash crops. Many of the cash-crops and the cover-crops are flowering, providing great seasonal diversity for pollinators. Thomas’s farming is truly productive, profitable, and works in sync with nature – a real symbiosis. He is a shining example of how innovative and cutting edge organic arable farming can be. Thomas tells a story of how a hedgehog followed by her prickle of hoglets nonchalantly rambled past him on his farm lane one day – then he knew he must be doing something right!  More information on Thomas’s farm here.  Ambassador since 2020

‘Cover Crops’

by Andrew Bergin

 Cover crops (also called catch crops or green manures) are sown in the intervals between cash crops to provide ground cover, to capture soil nutrients and to improve soil characteristics. They may be grazed but are primarily grown to improve soil and do this in a number of ways:

Harvest Sunlight – green cover crops are photosynthesising and this free energy is wasted without a crop to capture it.

Keep Soil Alive – the cover crops support a lot of creatures. Certain fungi and bacteria will consume the crop when it dies and others work with it while it is alive. The microbes in turn support tiers of other creatures, right up to the worms and the birds who consume them. All of them can benefit subsequent cash crops. Pollinators also benefit form late flowers in autumn and early ones in spring.

Protect Soil from Weather – the canopy of the cover crop reduces the compaction that rain falling on bare ground can cause. It reduces the amount of soil washed away after heavy rain, and the loss of the nutrients with it. Cover crops can keep ground warmer, allowing it to wake up earlier in the spring.

Improve Soil Structure – the variety of roots in cover crops helps to break up compaction and create channels for air, water and even worms to circulate. Root exudates improve the soil structure and help to build stable organic matter.

Diversity – cover crops offer a chance to grow a wide variety of plants together in soils that normally host only one species at time. The synergy of this community of plants accelerates all the other benefits of covers.

Grazing – grazing covers can help to recoup the cost of establishment and the cycling of nutrients through livestock can benefit the soil. On the other hand, some of the nutrients leave the field on four hooves and you need to keep an eye on the damage that those hooves can do to your precious soil.

Practical Tips

Sow early – “A day in July is worth a week in August is worth the whole of September.”

Seed choice – the more plant families included the better – cereals, grasses, legumes, brassicas, chenopods, etc. Lots of premixes are available. Keep an eye on clashes with cash crops in the rotation.

Cost – start small, simple and cheap. But anything is better than nothing.

Feed – covers can be a great place to apply organic manures. They will give extra growth in the cover and remain in the field in an ideal, insoluble but plant-available, form.

About Andrew Bergin

Andrew Bergin farms 320 acres of tillage. He has been practicing no-till cereals for a good number of years, while managing the soil in a way to promote high levels of biological benefits. Andrew sows cover crops, and is constantly trailing on farm what species work best for his soil and rotation. This is an integral part that has allowed Andrew prosper in this system that benefit both the environment and the farmer.  His approach is to improve the soil structure and the microflora and insect populations in the soil.  Crops include spring and winter cereals, oil seed rape and peas.  Integrated crop management is practiced to minimise the use of sprays – no insecticides have been used in the last 5 years.  Pollinator strips, 6 – 10 meters wide are in place around most of the tillage fields margins, attracting large numbers of insects and birds.  In addition, a number of fields margins and other areas, which were difficult to cultivate for tillage crops, have been planted with trees – oak, beech, birch, holly, hazel, pheasant berry etc. Andrew’s farm is moving away from excessive inputs and looking bring new ideas and knowledge as well as a positive focus to a type of farming generally considered less environmentally friendly. “It is important to get involved in and look at local research so we can each discover what is best for our own soils, not what chemical is best to throw on it.”  More information and a short film on Andrew’s farm here.  Ambassador since 2020


Go to our main Groundtips page to see what other subject areas have been covered by our network of farmers, bringing their tips and advice to you straight from their farms.



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