21 July 1995

Basic ingredient must be good, says silage master

Productive grass swards are the cornerstone of one Co Durham farming business. But it is top-quality grass silage and not grazed grass that it seeks. Sue Rider reports

DON Wilkinson takes black-and-white bulls to 600kg on a 16-month silage beef system with help from his wife Julie and son-in-law John.

Stocking comprises 500 bulls at various stages of rearing from calves to finished animals. Grass silage is the basis of the mainly home-grown complete diet-fed ration.

That Mr Wilkinson is one of the countrys best silage-makers is not in doubt. He has won the British Grassland Societys national silage competition twice and this years first-cut, which analysed at 74 D-value, 11.9 MJ/kg DM ME, 9.9 MJ/kg DM FME, 17.3% crude protein, pH 5, and 4% ammonia N, is a tribute to his skills.

But he is the first to admit that high yields of nutritious grass silage depend on productive grassland.

Half his 130ha (320-acre) Newton Ketton Farm, Brafferton, Darlington, is down to grass. The rest is in winter wheat and winter barley, grown in a rotation of three years grass, two years wheat and one year barley.

The winter barley has been grown in the past to allow an early start to autumn reseeding. But it is less productive than wheat on the farms heavy clay soil and this year Mr Wilkinson will grow just grass and wheat.

He plans to secure an early start by harvesting some of the wheat as whole-crop next summer, using arable area aid to offset the variable costs of growing the forage.

His grass mixture is based on intermediate perennial ryegrasses without clover (see panel). He used to grow earlier perennial varieties, and Italian. These produced an excellent first-cut but went to seed and proved tricky to manage in mid- and late season. This was unacceptable for someone who aims to take at least four cuts of silage.

Clover is excluded from the mixture because it does not thrive under the high nitrogen cutting regime Mr Wilkinson prefers.

Seed-bed preparation is crucial to achieve that all-important firm, level base. At Newton Ketton that involves ploughing and several passes with a power harrow and flat roller to break down and consolidate the soil. The extra cultivation needed on the heavy land can be a disadvantage because it encourages moisture loss.

Mr Wilkinson aims for a "nutty" rather than fine seedbed. "Fine seedbeds on our heavy soil would cap after heavy rain, making it difficult for young seeds to push through," he said.

During final cultivations a 0:20:32 compound is applied at two bags/acre.

Most of the fym is spread on the arable land after ploughing and only goes on before an autumn reseed when time allows.

Conventional drill

Grass is sown using a conventional grain air drill, which Mr Wilkinson said gave better establishment than broadcasting. Seed is placed at a 10mm-20mm (0.4in-0.8in) depth so it is in contact with soil moisture and drilled at a rate of 37kg/ha (15kg/acre).

"This seed rate is higher than average but with three-year silaging leys we rely on plant population rather than tillering," he said. "It is also worth remembering that our grass seed mixture contains tetraploid and hybrid seeds which are larger than the diploids."

The added advantage of drilling the grass seed is that it allows the creation of tramlines in the crop, just as with cereals. These are used to make it easy to apply fertiliser accurately. "They take the guesswork out of fertilising," added Mr Wilkinson.

In late autumn sheep are brought in to keep the sward tidy and weed free and they stay until Christmas.

Fertiliser is applied in early spring ready for first cut in early May. Using the formula of two units/day from time of application to time of cutting, Mr Wilkinson applies 150kg N/ha (120 units N/acre) of a 27:5:5 urea-based blend in split applications in late February and early April.

"We calculate what the crop needs and apply that amount so there is little nitrogen residue left at the end of the season," he said. "But the crop doesnt go short of nitrogen." This ensures the crop is still growing vigorously at cutting and produces a quicker regrowth.

He allows six weeks growth between first and second cut and applies a 25:0:16 K-nitro compound at 94kg/ha (75 units/acre) of nitrogen after each cut.

Second cut yield

This years second cut yielded 10t/ha (4t/acre) at 50% dry matter. Mr Wilkinson stressed this was not wilted silage that was left to sweat in heavy swaths. The cut grass is spread out over the ground and raked back into swaths an hour or two before the forager picks it up.

Silage is stored in two earth-walled clamps, fed out using a shear-grab to keep the clamp face tidy and offered with ground wheat as a complete diet feed to animals over nine months. Younger stock also receive fishmeal as an extra protein source although Mr Wilkinson questions whether this policy is still necessary given the high protein value of his high dry-matter silage.

He puts the total cost of reseeding, including cultivations and seed, at £222/ha (£90/acre) or £74/ha (£30/acre) a year for the three-year ley. He estimates that his grass silage costs, spread over the four cuts, comprise £74/ha (£30/acre) for reseeding, £173/ha (£70/acre) for fertiliser, and £247/ha (£100/acre) for harvesting, leaving a total cost of £494/ha (£200/acre). With yields of 5t dry matter an acre, the cost is £40/t dry matter.

Don Wilkinson (left) and son-in-law John Bainbridge treat grass like an arable crop to maximise production.There is no clover in the mixture.