Cover crops may be at the height of arable farming fashion right now but growers in the north of England and Scotland have been warned they should not blindly follow the crowd without having clear reasons.
Like many growers, Richard Reed, host of the AHDB Berwick-upon-Tweed monitor farm, is asking whether cover crops can help him improve his soil health.
To find out he drilled trials of four different cover crop mixes, but in Northumberland a tight window for fitting a cover crop into the rotation can impact on future cropping choice.
Mr Reed said: “I’ve learned so far that cover crops can be expensive to grow and timeliness is key. Where we are up north the window is tighter.
“We need to focus on what we can grow well to make sure we do achieve something at the end of it.”
Cover crops uncovered
The cover crop trial mixes were:
- Vetch (60%), red clover (20%) and Egyptian clover (20%), costing £80/ha. The clover had all been lost to slugs.
- Black oats and vetch, costing £39/ha. The black oats were grown to see if blackgrass could be suppressed through allelopathy (the biological phenomenon where one plant inhibits the growth of another).
- Black oats and berseem clover. Again, the clover had been lost to slugs.
- Oil and tillage radish, European oats, phacelia and forage rye, costing £37.85/ha.
Dr Liz Stockdale of Newcastle University has been working with Mr Reed and AHDB on the project and said growing cover crops in the North should be done after thinking about the subsequent cash crop.
She advises Northern growers to not be swayed by what other growers are doing and instead focus on what works best for them.
“Don’t rush into cover crops because everyone else is thinking about them. It’s important to think about what benefit you want from them,” she warns.
Predominantly cover crops are being thought of as a soil improving measure, but they can also be used for weed control.
“Keeping crops growing over the winter is a good thing for soil health, biology and structure and to minimise run-off and soil erosion.
“But how you make that work effectively depends absolutely on your own system – your soil types, the nutrient balance, the cropping system into which you’re incorporating the cover crops.”
She adds that growers should consider how they will destroy the crop and whether it would be possible to travel across the land and the right times if necessary.
“Here in Berwick, the wheat harvest doesn’t often finish until the start of September, so cover crops can’t be established until after that,” said Dr Stockdale.
“We’ve seen here that the grass-based cereals and rye-type cover crops establish much more quickly and deliver a much better cover than legumes.
“So in the north of England we might focus on these cover crops, whereas in the south of England legumes and other crops might be suitable.”