When looking at the practicalities of growing cover crops around the Scottish Borders, farmers were this week advised to carefully consider drilling dates and the amount of time the crop would have to get established.
Speaking at a monitor farm meeting in Northumberland, Dr Liz Stockdale of Newcastle University said that there was a tight window for fitting a cover crop into the rotation – a fact which had a major impact on the choice of crops.
“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,” she told the event organised by the Agriculture and Horticulture Development Board (AHDB).
“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 this far north we might focus on these cover crops, whereas in the south of England legumes and other crops might be suitable.”
Stockdale also said that with most cover crops in the ground between September and March, the opportunity for fixing nitrogen was limited.
“Beware of people who say that cover crops can fix nitrogen. Especially this far north, there’s not the sunshine to do this. To fix nitrogen in the soil, the bacteria need sugar from photosynthesis and this mostly happens in May and June.”
She said the key question to ask was whether it was worth the hassle of growing cover crops.
“It’s really difficult to balance everything. We need to focus on the whole rotation, and to make cover crops work on a site-by-site basis,” she concluded.