5 September 1997


SET-ASIDE field margins sown to relatively cheap grass mixtures and managed to offer twin habitats are bringing more wildlife onto land at ADAS Boxworth, according to team manager James Clarke.

Now in their third year, the margins are at least 20m (66ft) wide and mostly on the north and east sides of hedges and woods where crop performance tends to be lower than elsewhere. "Yields in the first 10m are often 1t/ha less," explains Mr Clarke.

About two-thirds of the farms original 15% set-aside requirement was established as field boundaries. "In other words we had about 10% as margins, and under the voluntary arrangements we have left it at that."

Detailed monitoring of the developing fauna and flora shows the verges are well used by birds and small mammals.

Mowing policy

Key to encouraging wildlife is the mowing policy, he believes. This involves cutting the main area nearest the hedge or wood just once a year in late summer. A 3-5m (10-16ft) wide strip nearer the crop is trimmed more often.

Rotavating a 1m (3ft) wide band next to the crop helps stop grass weeds encroaching into the cropped area.

ADAS has tested four types of grass mixtures for the margin cover. Seed costs vary considerably. The simplest and cheapest at about £15/ha (£6/acre) is based on ryegrass with some crested dogstail and sweet meadow grass.

Another, mainly fine-leaved fescues, cost £70/ha (£28/acre). "And if you add wild flowers you can easily spend £300/ha."

Much the best though seems to be one including cocksfoot and timothy with some ryegrass and fescues at only £17/ha (£7/acre). The tussocky sward it produces provides plenty of cover and suppresses many weed species including sterile brome and thistles, explains Mr Clarke. &#42


&#8226 20m+ grass strip near woods and hedges.

&#8226 Mow once a year near wood/hedge.

&#8226 3-5m near crop mown more often.

&#8226 1m cultivated strip nearest crop.

&#8226 £15/ha grass seed cost.

&#8226 Big wildlife benefits.