Experts doubt nitrogen savings

Agronomists are sceptical that substantial nitrogen savings are on the cards – even after the driest winter since 1975/76.

The ADAS view, backed by soil sampling, is that unusually low over-winter leaching has left higher than normal levels of nitrogen in many fields.

Most of central and eastern England had less than 150mm of excess winter rainfall, the majority less than 75mm and some areas had as little as 25mm.

Reports from around the country suggest soil mineral Ns are normal to above normal, says senior research soil scientist Peter Dampney.

Indeed one maltster is said to be concerned that farmers may overdo nitrogen inputs and risk producing excessively high grain N contents.

Recognising uncertainty among growers about the requirements to comply with NVZ rules, the EA has issued specific guidelines, notes Mr Dampney.

But despite apparently higher than normal soil N supplies, Dalgety’s Mike Jeffes expects them to make only a minor difference to fertiliser practice on the firm’s Throws Farm, Essex.

“For the first time in six years’ sampling we have N-min levels of over 100kg/ha.”

But with the optimum N input for 13% protein Malacca wheat ranging from 36kg/ha last year to 340kg/ha in 2004, he questions the value of relying too much on post-winter soil levels to drive applications.

“I might take a little bit off the first dressing.

But you don’t know how much of the soil N will be taken up, and there can be big errors associated with the tests.”