17 July 1998

Think now about best mix for needs

Grass is an expensive crop, so achieving good

establishment is crucial. In this special feature, edited by

Emma Penny, we look at variety choice, pest and weed

control, and why tramlines are a good idea in grass

AMPLE forage stocks and grazing create an ideal opportunity for reseeding swards which will produce higher grass yields next year.

Jim McVittie, forage specialist at NIAB, Cambridge, says producers should take the opportunity to take some grass out of production now and create higher yielding swards that will help cut production costs in the future. Despite current low prices for milk and meat, producers should take a longer term view and invest in grass, our cheapest feed, he adds.

A reseed will allow newer, higher yielding, varieties to be sown. The recommended grass variety list trials show an improvement in crop yield of 0.5% a year. That is why only 10 of 52 perennial ryegrass varieties on the recommended list are over eight years old, he says.

Variety list trials show that in a normal season the average dry matter yield of a first year ley is 15.2t/ha(6.2t/acre), 25% higher than a second year ley at 12.2t/ha(4.9t/acre), but you have lost some yield when new seeds are establishing, he explains. However in a drought year the benefit of a new ley is greater, with a 50% higher yield, 12.3t/ha (5 t/acre), than a second year ley at 8.1t/ha (3.3t/acre).

"Reseeding advantages are greater in conditions when grass is in short supply. These results offer a good reason for having some new grass around the farm," says Dr McVittie.

Also improvements in grass types and increasing diversity of individual varieties may see changes to the way components of seed mixtures are selected.

According to Dr McVittie it is unlikely that the number of varieties in a mix will change as this would increase cost and be too complex. However, mixes could become more adventurous exploiting seasonal growth and enhancing the productive life of swards.

"Hybrids could be included in an Italian mix to lengthen sward life or a perennial mix to increase first and second year yields," says Dr McVittie.

The best hybrid variety yields just 3-4% less than the best Italian variety over two years, but could continue to yield well in a third and possibly fourth year, he says. Hybrids could help achieve good first cut silage yields which, together with their ground covering ability and improved digestibility, makes them better suited to grazing than Italian ryegrass.

"To ensure the right mix is selected for a field, producers must approach the seed merchant with details of sward use and the weaknesses of grass production on the farm."

For example, grass supply may be adequate but grass quality may be restricting stock performance, or the grazing season may be too short. According to Dr McVittie merchants have detailed information on varieties, meaning they can to select a mix that will meet the given requirements.

"Many producers buy seed on price, however seed is a small part of the cost of reseeding with other costs more difficult to identify, and they should be prepared to invest more; grass seed is cheaper than maize seed which is bought each year," adds Dr McVittie.

Jessica Buss

VARIETY CHOICE

VARIETY CHOICE

lMore adventurous mixes.

&#8226 Hybrid longevity benefits.

&#8226 Speak to seed merchant.