29 October 1999

Soil tests are vital after strob use

STROBILURIN use last season means soil mineral nitrogen testing will be vital next spring, delegates at the first HGCA Agronomy Roadshow at Wye, Kent heard on Tuesday.

"If you are not already doing soil mineral nitrogen tests then you must seriously think about it following strobilurin-treated cereals," ADASs Bill Clark told delegates.

ADAS work shows 80-100kg/ha (64-80units/acre) less nitrogen is available to crops grown after strobilurin treated cereals than those after a triazole treated crop. Larger root bulk and higher volumes of chopped straw are thought to lock up the nitrogen. This years high yields could exacerbate the effect.

However, autumn nitrogen application was ruled out. "There is no suggestion of strobilurin treatment affecting autumn establishment."

Nitrogen requirements in the strobilurin treated crops itself is unchanged or only very slightly higher, he added.