11 April 1997

Lucerne insurance

In our new series on forage legumes, Jonathan Riley finds out how lucerne allows one Cheshire milk producer to sustain milk yields despite poor summer grass growth

LUCERNE enables Nantwich-based milk producer Richard Ratcliffe to sustain his 125 milkers 9800 litres a cow average despite poor summer grass growth.

At his 80ha (200-acre) Hill Farm annual rainfall is only 635mm (25in) and the light, sandy loam soil on sandstone bedrock limits grass growth to two periods a year between March and June and between August and December.

"In mid-summer, grass growth ceases and so we switch to feeding stubble turnips and lucerne, which consistently yields 5t/acre dry matter, even in years like last year when rainfall was only 12.5in," he explains.

"This consistency provides us with an insurance, making lucerne an excellent crop for us to grow. But unlike lucerne, grown in the south, where warmer, sunnier weather raises protein levels to 25%, proteins recorded in Cheshire are similar to that of grazed grass at 16% to 18%."

Digestibility at about 70 D is also equivalent to young grass, but, unlike grass, as lucerne matures digestibility is sustained longer.

The diet is, therefore, similar to the grazed grass and concentrates ration that the cows receive in the early summer, ensuring little change in the milk composition and yield despite the lack of grass.

Lucerne silage is fed at about 6kg a head along with 4kg of concentrates plus stubble turnips.

The first of four cuts of lucerne is taken at the end of May but Mr Ratcliffe explains that the date of silaging is not as important, as it is with grass silage because digestibility does not fall as quickly.

But it is vital to ensure the crop is harvested when the weather is dry because the crop needs to have a high dry matter % for a good fermentation. At Hill Farm the crop is wilted for three days before baling.

"Choosing a variety with good standing ability reduces lodging and improves the dry matter of the crop.

"This also makes harvesting easier and limits handling, which reduces the amount of leaf loss, an important factor in maintaining the nutritional value of the crop," he says.

Though no nitrogen is needed, 502kg/ha (4cwt/acre) of 0:10:30 is applied in January. Lime should also be applied to produce a pH of 6.5.

"We monitor soil pH closely and apply 1.5t/acre when pH falls to 6.3, which means we are liming every other year," says Mr Ratcliffe

Muriate of potash is also applied after the first three cuts of lucerne at 125kg/ha (1cwt/acre). The fourth cut is taken in mid-October after the first frost, which renders the plant dormant until the next year.

Weed control can then take place in late December-January with an application of paraquat, which burns off all green matter in the field without killing the deep rooting lucerne plant.

"Weed control is vital because the lucerne plant is very susceptible to the effects of competition. This is particularly so when establishing the crop, and an application of Roundup to destroy perennial weeds should be made in the autumn," explains Mr Ratcliffe.

But he recommends that the first step in establishing a good crop is to choose a well drained, subsoiled site to encourage root growth.

Ideally, the ground should be ploughed in December and left until mid March when a firm, fine and level seed-bed should be created.

At Hill Farm, lucerne was drilled after a first cut of grass silage taken in the first week of June to maximise the yield of dry matter from the field.

"After the seed-bed is prepared cultivations can be used to control the first flush of weeds before 22lb/acre of lucerne seed is drilled," says Mr Ratcliffe.

He advises drilling when wet weather is forecast so the crop emerges rapidly ahead of weeds.


&#8226 Choose a well drained site.

&#8226 Produce a fine, firm and level seed-bed.

&#8226 Control weeds carefully.

Lucerne is an insurance against summer drought for Richard Ratcliffe.


&#8226 Choose a well drained site.

&#8226 Produce a fine, firm and level seed-bed.

&#8226 Control weeds carefully.