12 June 1998

More clover & pastures new is RACsheep plan

Increased production of

grass and clover is the aim

of one Glos flock being used

to demonstrate best

grassland practice for

lowland sheep units.

Sue Rider reports

PASTURE renovation and increased reliance on clover is the two-pronged approach to boosting sheep production off forage at the Royal Agricultural Colleges Harnhill Manor Farm, Cirencester, Glos.

Its 750 March/April lambing ewes, run on 50ha (124 acres) of permanent grass and 30ha (74 acres) of short-term leys, is demonstrating best grassland practice for lowland flocks as part of the grassland demonstration programme "Grassland Management: Practice into profit", run in association with FW and funded by MAFF, Milk Development Council, MLC, British Seed Houses, and Barclays Bank.

At a farm walk for the Cotswold Sheep Group, shepherd Justin Morson explained that much of the forage area is permanent pasture, and, because it is rented annually, it has been difficult to improve productivity.

"We have grazed the pastures with sheep for the past 10 years," he explains. Ewes, and their lambs, are stocked at nine a hectare (3.5-4 ewes and lambs an acre), and set-stocked in groups which rotate around the fields.

Slot seeding clover – levels were low in the permanent pasture – and ryegrasses into swards was tried in one field last autumn to boost productivity. Some 7ha (17 acres) of permanent pasture was sprayed with Dart at 1 litre/ha (0.4 litres/acre) before seeding on Sept 24 with ryegrass and white clover (see panel). To avoid Frit fly damage, the sward was sprayed with 1.67 litres/ha (0.7 litres/acre) of Dursban 4 on Oct 25.

But, as grassland lecturer Gerry Lane explained, the slot seeding has not been very successful.

"There is not as much of the new grass and clover as expected, perhaps because we went in too late. Or it just could be that renovation by slot seeding is slightly overplayed," said Mr Lane. He felt oversowing by broadcasting could work as well – without the hassle or the cost of slot seeding – and plans to try it this year.

Shorter-term grass/clover leys grown as part of an organic cereal rotation are the more productive pastures on the farm, providing both silage for winter feeding and aftermath grazing for store lamb grazing and finishing.

Most of the organic leys are established by undersowing in winter cereals, explained Mr Lane. One field, direct sown last September, includes the tetraploid hybrid ryegrass Dalita, sown at 22kg/ha (9kg/acre) and the red clover Merviot, at 9.8kg/ha (4kg/acre). "The seed rate for the ryegrass is slightly lower than usual and for the clover slightly higher to ensure the clover has chance to establish," he said.

"As a tetraploid the ryegrass has a high sugar content, and is less aggressive than the diploids, making it a good companion grass for clover. And being a hybrid it should be more persistent than an Italian. Most hybirds last for about two years but newer varieties, such as AberExcel, will last even longer.

"The ley was drilled into a reasonable seed-bed and both the ryegrass and red clover established well, although we have had to graze the sward this spring to take out the weeds."

A longer-term ley undersown in April 1993 will provide a large first cut of silage – about 13-14t/ha (5-5.6t/acre) – and valuable aftermath grazing for the lambs after weaning. It also includes hybrids for persistency, and tetraploids for compatibility with clover.

"The blend of large and small-leaved clovers should ensure the mix survives grazing and cutting regimes, with smaller leaved varieties such as S184 for grazing and the larger leaved Alice for cutting," said Mr Lane. Cocksfoot was also included for its drought tolerance.

"When you sow a ley with Cocksfoot, a later heading variety such as Mobite is best, otherwise it will come into ear before the ryegrass is ready for cutting, and it will lower the D value of the rest of the sward."

Mr Lane estimated that 30-40% of this sward was clover. That would be contributing a lot of nitrogen – 150-200kg/ha (120-160 units/acre) – worth £60/ha (£24/acre) in saved bag fertiliser. "This is a saving conventional farmers could make just as easily and more could introduce clover to save costs."

Annual fertiliser use on the non-organic grassland on the farm is about 150kg/ha (120 units/acre), with 50kg/ha (40 units/acre) N applied as solid ammonium nitrate on Mar 16, another dressing applied in early May, and further dressings applied monthly.

To reduce the need for regular fertiliser applications, and achieve more even grass growth throughout the season, 187kg/ha (150 units/acre) Chafer N39 plus the nitrification inhibitor Didin has been applied to one 5ha (12-acre) field. The Didin ensures nitrogen is released gradually over the season.

"It is an excellent system for sheep production. We only need to fertilise once and get a continuous supply of grazing. It costs about £13/ha. But this is more than offset by not having to spread fertiliser three or four times a year," he said.

GRASS MANAGEMENT

&#8226 Pasture renovation by slot seeding.

&#8226 Clover leys for silage and grazing.

&#8226 Slow release nitrogen to cut costs.