25 February 2000

Plenty of soil nitrogen for most wheats

SOIL mineral nitrogen tests suggest there is no need to rush in with top-dressings.

But mixed results mean assumptions about individual fields could be dangerous, say experts.

"Comparing the average across the UK there is about 50% more nitrogen available in the soil now than at this time last year," says Kemira agronomist George Fisher.

But that average hides regional variations. "In the East Anglian and Lincs bread basket the average is up 65%."

For most wheat growers that means there is plenty of time to assess tiller counts and crop condition and no urgency to apply first top-dressings.

But wet weather has left mineral Ns very low in north-east Scotland. "Nitrogen levels are where they were last year – 33-34kg/ha from a 0-60cm profile."

Across England, Terra reports N levels similar to this stage last year in a 0-90cm profile, but with marked variations. "The average across 14 sites is 74.8kg/ha, but the range is 19.5-130kg/ha," says the firms Richard Martin.

The low result, off Lincs brash, suggests thin wheat on that land needs nitrogen now. But the high figure, from Northants heavyland with a history of sewage sludge use, should prompt different tactics, he says. "Growers can afford to hold back on fertile sites."

Dr Fisher advises giving first wheats priority when sampling and assessing each soil type separately. ADASs Peter Dampney echoes that.

"Target where high nitrogen levels are expected – after a history of manures, grassland or other high nitrogen residue crops." &#42

SOIL MINERAL N

&#8226 Mixed reports on soil nitrogen.

&#8226 No N urgency for most cereals.

&#8226 NE Scotland very low N levels.

&#8226 Back to normal on most farms.