Sowing a cover crop mixture from a range of seeds such as mustard, radish, vetch clover, forage oat or rye post-harvest can protect bare soil from erosion, prevent loss of nutrients through leaching and have beneficial effects on soil structure and soil life. They can be used by farmers to meet their greening requirements under the Basic Payment Scheme.
With so many positive benefits to the soil and the wider environment its little wonder the practice is being taken up by increasing numbers of farmers south of the border, but are they appropriate for Scottish conditions?
There are a number of factors that Scottish farmers need to consider before diving into post-harvest cover crops:
- Timing - Ideally a cover crop needs to be sown in August which means following oilseed rape, winter barley and on occasion after spring barley.
- Delayed harvest - small seeds will struggle to establish and grow when sown after the 2nd week of September resulting in all of the cost and few of the benefits. If you are further north, e.g. Aberdeenshire or the field is at altitude or north-facing you need to be two weeks earlier. If delayed, sow a mixture of larger seeds such as triticale, barley, oats or rye to ensure you get establishment and cop cover.
- Nutrition - Crops will produce more biomass above and below the ground the more fertile the site. If the site has a low nutrient status consider applying a fertiliser or organic manure such as slurry, digestate or muck.
- Rotation factors - Mustard will establish quickly, but it will also increase the incidence of root disease Clubroot, so needs to be excluded if brassica crops are grown in the rotation.
- Pests - Slugs can be a real problem and can wipe out emerging seedlings and continue to graze on established plants.
Cover crops can and are being grown by farmers in Scotland and consideration of the above will help to reduce the risks and ensure a successful crop.
This article from Farming for a Better Climate was funded by the Scottish Government as part of Scotland’s Farm Advisory Service and first published in the Farming Scotland Magazine during August 2018.
Scotland's Farm Advisory Service has a useful Cover Crop Information Note looking at many of the common cover crops found within mixes often used on farms.