28 March 1997

Trailing shoe keeps sward cleaner

By Sue Rider

LESS sward contamination and better nitrogen use are promised by a slurry spreading technique to make its debut at Muck 97.

Known as the trailing shoe, the device places slurry on the surface beneath the growing crop, explains ADAS soil scientist Ken Smith.

"By running under the sward the shoe cut surface contamination of plants, one of the disadvantages of broadcast or band application," says Mr Smith, who will be demonstrating models of three surface placement techniques – shallow injection, trailing hose and the trailing shoe – at the event.

"The trailing shoe reduces sward contamination compared with the hose and, because the slurry is under crop canopy, smell is reduced as is crop scorch and ammonia emissions," he says.

MAFF-funded work by ADAS and the Institute of Grassland and Environmental Research has compared the levels of ammonia emissions from surface broadcast slurry with that applied using shallow injection or the trailing shoe. Two years results have shown that 42% of the ammonium N applied was lost using conventional surface broadcasting, 27% lost using the trailing hose, 26% the trailing shoe and 21% with shallow injection.

"We are trying to find out how to reduce ammonia emissions, which is not only important environmentally but should help farmers recycle manures more efficiently, conserving more nitrogen which would then be available for crop use," he says.

The shoe substantially reduces emissions compared with broadcasting, and is nearly as good as shallow injection. The advantage of the shoe over shallow injection, however, is that capital and running costs should be lower, as the wearing parts of the machine are not cutting through the soil.

And not having to penetrate the soil surface, the shoe is likely to be more successful on stony soils, he says. &#42

Trailing shoe system is designed to place slurry on the soil surface, beneath the growing crop.