31 May 1996

Savings on fertiliser…

SUMMER-sown white clover could help to reduce reliance on costly nitrogen fertiliser, according to Dyfed-based Genus consultant John Griffiths. He suggested white clover can be slot seeded into existing pasture after first- or second-cut or with a grass reseed before September.

July and August were the best months for establishing clover provided there was sufficient moisture and an open grass sward. After August temperatures may fall below the 8C (46F) needed for good germination. Grass was more tolerant, however, needing a temperature of only 5C (41F) to grow.

"A grass/clover mix survives short-term drought better than grass," he said. "And improved varieties developed in the UK have greater persistence than some imported types.

"White clover varieties are classified according to leaf size and the choice should be appropriate to the intended management."

For dairy cows he advised mixing medium and large leafed clover so that it could be suitable for cutting and grazing.

"However, clover is best used in grazing swards because it is difficult and expensive to control dock weeds in fields with clover."

For reseeding pasture Mr Griffiths advised drilling 4kg/ha (3.5lb/acre) of white clover with 25kg/ha (22lb/acre) of intermediate and late perennial ryegrasses.

To ensure good establishment when seeding in clover after silage dont apply nitrogen fertiliser, he warned. But before sowing ensure soil has a pH of 5.8 and that it was kept at 6 to 6.5. Adequate phosphate is also needed and phosphate and potash levels should be maintained at index 2.

"Aim for a clover content of 35-40% in the sward," he says. This will reduce the nitrogen fertiliser needed. But early nitrogen can be applied to grass that begins growing two weeks before the clover. That is providing pasture is grazed before the clover starts growing to avoid crop competition, adds Mr Griffiths.