The incorporation of clover into existing grass swards can result in improvements in animal performance, profitability and reduced greenhouse gases (GHG) – all drivers for long-term sustainability.
Ruth Ruddell, a technologist at the College of Agriculture, Food and Rural Enterprise (CAFRE), said: “If you’ve been considering including clover but not yet got round to it, then now is the latest suitable time for stitching-in to ensure establishment for next year. Stitching in provides a low-cost method to add clover into existing swards.”
Clover brings a variety of benefits as it fixes nitrogen from the atmosphere and so greatly reduces the quantity of inorganic nitrogen uses.
Therefore, the process saves money while maintaining production levels and reducing the farm carbon footprint.
As clover covers build through the next years growing season, it helps maximise time at grass by extending the grazing season at the backend of the year.
In addition, biodiversity is enhanced by provision of a nectar source for bees many species of which are threatened in the UK and Ireland.
Pollinators are important to farmers who grow insect-pollinated crops which are important to our economy and to the health of our environment.
For the best success, you should select a field that has adequate drainage and minimal soil compaction. All swards benefit from having soil pH, P and K status at optimum levels however legumes are especially sensitive to lower levels.
Carry out a soil analysis if you have not recently. Use lime to correct your pH, with a target range of pH 6.3 – 6.5 as this is very important for the maintenance of clover.
Ruth Ruddell continued: “The following actions will provide the best change of a successful establishment when stitching-in white clover – good contact between soil and the seed to make a ‘hit’ and allow germination; moist soil conditions; light reaching the clover seed and seedlings; tight grazing to prevent shading out; and well-established seedlings so they can survive the winter.”
Selecting clover variety
When selecting your clover variety refer to the recommended grass and clover lists 2020/21, available from the British Grassland Society here.
If selecting white clover, then consider suitability by leaf size. Smaller leaf varieties are generally lower-yielding but more persistent, their stolons are close to the ground so they are recommended for sheep farms because they can survive the selective grazing of sheep.
Medium and large leaf varieties are more suitable for both grazing cattle and silage production. Cattle and dairy cows are less selective and graze less close to the ground than sheep.
Medium and large leaf varieties are able to establish in these longer swards provided careful grazing management is followed after stitching-in.
The management of the sward pre and post-sowing is key to success. This is important because clover seedlings become established in short open patches in the sward.
It is important that the sward is short from a cut of silage or tight grazing prior to stitching-in as this will allow good contact with the soil and light to reach the newly germinated seedlings.
A variety of methods can be used each with their own pros and cons, use whatever is most suitable to your farm. Stitching-in can be done by slot seeding/direct drilling or broadcasting following scarification.
Broadcasting can be done using a standard fertiliser spreader or other specialised broadcasting equipment such as an airseeder. Sowing rate is generally 4kg/ha or 1.5kg/acre but if you are topping up a sward that already has some clover then this can be reduced to 2.5kg/ha or 1kg/acre.
Use a mixing agent such as dry sand, granulated lime or if there is a soil requirement then sulphate of potash, mix half the required seed and spread. Then mix the remaining half and spread in the opposite direction, this is to ensure good coverage.
Ruddell concluded: “It cannot be emphasised enough just how important it is to ensure the field is regularly and tightly grazed to 4cm.”
“Continue this until the field is closed for winter and avoid very heavy grass cover. This is to prevent tall grass shading out the clover and allow the required light to promote stolon growth.”
“Clover stolons will spread much greater distances once they have light reaching them. Good establishment will reduce competition from other plants.”