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

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

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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