28 March 1997


Have you got the right mix for your grass reseed? Jessica Buss finds out how to go about choosing the right mixture

GRASS variety choice will vary depending on the use of the sward, but select new varieties and they will outperform those in the sward to be replaced.

That is because recommended variety yields have steadily increased at 0.5%/year, claims Jim McVittie, of the National Institute of Agricultural Botany, Cambridge. Replacing 10-year-old pasture should give you 5% more grass, he says.

New varieties are also much more persistent, and whereas Italian ryegrasses lasted only one year 20 years ago, they are now good for two and often for three years, adds Dr McVittie.

When putting down a sward to last for a few years, he advises sowing the best varieties available now to avoid falling behind in terms of potential yield.

However, with over 70 recommended varieties on the NIAB list, choosing the right ones is complicated, he admits. Many good mixtures are available or can be made for specific use.

"But beware of cheaper mixes that may contain non recommended varieties," says Dr McVittie, who points out that the cost of seed is a small part of the total reseeding cost.

"Grass is an important crop, so pay a fair price for good varieties." Cheap mixes may, however, be useful for catch cropping.

"When choosing a mix consider what you are going to do with it and how long it will be down," he says.

"For a predominantly cutting short-term ley, sow Italian ryegrass that will give high yields of silage for one or two years. Include hybrids and intermediate perennial ryegrasses for longer-term cutting leys. And although tetraploids may give higher silage yields and are more winter hardy, they are too wet for swards intended for hay so use more diploids."

For a pure grazing ley, that must produce high quality grass for stock throughout the grazing season, choose tetraploid perennial ryegrasses – these are more palatable for dairy cattle, he says. Dairy cattle will also benefit from later varieties for their higher digestibility will increase intakes, and can help increase milk production from forage, adds Dr McVittie.

"For longer-term dairy swards use intermediate and late perennial ryegrasses with high digestibility and a lot of tetraploids," he says. "Early perennials may be too early for dairy cattle, producing grass before they can get out."

These early growing perennials are suitable in seed mixes for sheep grazing, for they provide grass around lambing time. But to ensure growth throughout the season he also advises including intermediate and late ryegrasses in these swards – although sheep can graze away tetraploids when grazing hard. However, the mix of early to late varieties will make it difficult to make high quality silage from the sward because of the different heading dates, he warns.

When you have decided if the sward will be for silage, grazing or a mixture of the two and the length it will be down, Dr McVittie advises speaking to a good merchant.

"Look for a merchant who is a member of the NIAB grass seed levy scheme supporting the recommended list trials," he says. "These merchants have detailed up-to-date information on varieties."

The varieties recommended will vary depending on the situation. To check the varieties included in a mix use the NIAB grass variety leaflet produced for farmers which highlights variety strengths and weaknesses, advises Dr McVittie. &#42

Beware of cheap grass seed mixes

that may contain non recommended varieties, says Jim McVittie. There are 70 recommended varieties on offer.


&#8226 Decide on length of ley.

&#8226 Consider use – grazing, cutting, sheep, cattle.

&#8226 Find a merchant in the grass seed levy scheme.

&#8226 Avoid cheap non-recommended varieties.