11 April 1997

Urea N lost in the dry

UREA-BASED fertilisers should not be spread on dry ground until wet weather is forecast, warns ADAS consultant Brian Chambers.

He explains that 20% of nitrogen can be lost to the air from urea-based fertilisers spread on to thin crops of grass during dry weather.

"These losses can occur even when there is a frost on the ground but the process is more rapid in warm weather," says Mr Chambers. "The moisture in slurry is not sufficient to prevent ammonia loss from occurring," he adds.

"Losses from thicker crops are lower but without rain, slurry will coat grass leaves, and animals wont graze."

But for ammonium nitrate fertilisers losses are small and Mr Chambers advises their application even on to dry ground. &#42