Cereals 2009: Nitrogen rates for winter barley

Today’s high-yielding winter barley varieties need more nitrogen than DEFRA’s RB209 recommends – and they probably require some of it earlier than it’s normally applied, according to GrowHow.

Whether the results of the company’s two year’s of trials with ADAS would be reflected in the revised RB209 remained to be seen, said the firm’s Allison Grundy.

“We arranged the trials to encourage more people back into winter barley. A lot of rotations are getting very tight with people just growing wheat and oilseed rape.”

The work, at High Mowthorpe and Rosemaund in 2007 & 2008, examined the effects of five rates of nitrogen (60, 120, 180, 240 and 300kg/ha) on two-row Saffron and six-row Pelican, Miss Grundy explained.

“We were surprised to find that the rates in the current RB209 weren’t really enough.” At High Mowthorpe in particular, where the soil nitrogen supply was low – just 36kg/ha in February – and the crop contained only 7kg/ha, the yields continued to respond even at the highest rate.

That meant that the economic optimum was between 252 and 305kg/ha at a breakeven ratio of 3:1 and 194-232kg/ha at 12:1.

Overall the work suggested that for each tonne of yield above 7t/ha the crops required an extra 20-30kg/ha.ENDS 275 WORDS

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