Reseeding – can you afford to ignore your grassland?
Kieran Mailey, Beef & Sheep Development Branch, CAFRE
After a severe winter and a late spring, grass growth and grass covers are well below the normal levels for the time of year. It is worthwhile taking time to walk the grassland on farm and assess the quality of swards. Older swards with low perennial ryegrass content (less than 30 percent content) will be unproductive over the grazing season and will benefit from reseeding this spring.
Younger swards that were fertilized in March have responded well to the cold spring compared to older permanent swards. Young swards are also showing less signs of frost damage and as a result less dead material at the base of the sward.
The County Down and South Armagh Clover group got to see at first hand the benefit of new swards over old swards, when they met recently at the monitor farm of John Milligan, Castlewellan. The focus of the evening was to discuss grazing management for this year and the reseeding options for both a grazing sward and silage sward.
As part of the clover monitor programme, the group meet three to four times per year on the monitor farm. The purpose of the first meeting in May this year was to look at the success of different reseeding techniques and the subsequent management to maintain the clover and new grass varieties on beef and sheep farms. There was a lot of discussion generated on the evening on managing spring grass, as well as points to consider when reseeding.
There is little point in reseeding a field if it is not going to be managed properly. A new sward will quickly deteriorate due to a number of management factors such as:
- Over grazing – allowing weed grasses (meadow grass, bents and Yorkshire fog) to enter the sward again.
- Undergrazed – if not grazed out, or topped, at the end of each rotation will cause the grass to become stemmy and rejected by grazing stock. Grass will be slow to tiller out and clover will be difficult to establish.
- Heavy / late silage cuts – slows regrowth, removes high levels of soil nutrients and leaves the sward open.
- Low soil fertility / pH – low phosphate (P) and potash (K) levels will reduce grass yields. A low pH reduces the availability of soil nutrients, both in the soil and those applied as fertiliser. Clover swards are difficult to establish if fertility and pH is low.
Reseeding offers an opportunity to introduce clover into the sward. Clover can increase livestock performance by 10 percent in cattle and 25 percent in sheep. It is also higher in protein and trace elements such as Selenium and Magnesium than ryegrass.
The key points to establish a reseed, especially with clover, is to have a firm seed bed and ensure that there is good soil-seed contact and ensure the seed is not sown too deep (half inch deal) . Also, soil testing is crucial, as a pH of 6.0+ and P and K index of 2+ is recommended.
Management post-reseeding is also important; the sward should receive a maximum of 50 KG/ha Nitrogen (N) (40 units/acre) in a season, which can be applied through slurry or bagged fertiliser. All nitrogen should be sowed by May, as clover growth generally occurs over June and July when grass growth is declining. Sowing N late in the season will cause the grass to out compete the clover and thin it out in the sward.
Likewise, grazing down to 4cm in each grazing rotation until late May is vital to allow the clover plant the opportunity to spread. It also allows light into the plant and cuts down competition from ryegrass.
If weeds are a problem use a clover safe spray such as Alistell or Squire. Only spray when the clover plant has developed all three leaves. Grazing weanlings or sheep will encourage clover spread, as will regular topping of the sward. Top the sward down to two inches for best results.
May is an ideal time for reseeding as the sward will establish quickly however weeds can be more of a problem than in the Autumn.. Autumn time is also suitable, but due to shorter days and cooler temperatures, some reseeds may not be well established before the winter period sets in. As a result clover reseeds should be completed by mid August.
Reseeding and good grassland management are essential in beef and sheep production as grazed grass is still the cheapest feed available. A well managed sward can have an energy value of 12 Mj ME/KG and a protein value of 20 percent. For more information on reseeding, or on joining a clover monitor group, contact your local beef and sheep advisor.
Members of the Co Down and South Armagh Monitor Group discuss grass covers on the monitor farm of John Milligan at Castlewellan
