5 May 1995

Compounds can give a kick start to swards

By Jeremy Hunt

COOL dry conditions of recent weeks, which have pegged grass growth in many areas, have highlighted the "kick start" qualities of nitrogen and phosphate when present in a water soluble form in a compound fertiliser.

Trials under way at Michael Taylors Russell Farm, Burton-in-Kendal, Cumbria, show clear benefits of compound over blends with taller and denser sward heights on both grazing and silage ground.

Both grazing and silage land were set-aside for the trial which set out to compare sward height and mineral content of grass receiving N and P compound against straight N fertiliser applied at the same level of nitrogen.

Kemira Fertilisers, which organised the trial, split a 1994 autumn re-seed into three sections applying Nitraprill to two and the N and P compound to the third.

The compound was applied at 2.5 bags an acre (68 units N + 25 units P); the Nitraprill went on at 2 bags an acre (68 units N). There were two application dates – Feb 27 and Apr 10.

Yield assessment, using the New Zealand Falling Plate method to measure sward height and density, estimated a grass yield from the compound treatment at 5.15t an acre of fresh grass from measurements taken on Apr19. That compares with an average 3.8t from the two straight N applications.

"The figures suggest an extra cost of around £8 an acre for the compound but that is set against a yield benefit, as estimated at the mid-April growth stage, of 1.5t of fresh material," said George Mackenzie of Kemira.

"Our research confirms findings from trials carried out by the Scottish Agricultural Colleges. Particularly in a cold spring like this one there is a marked advantage in growth from using a compound fertiliser instead of straight N."

Mr Mackenzie said the water soluble nature of the N as ammonium nitrate and the P as ammonium phosphate increased the efficiency of the nitrogen and achieved improved uptake.

The "yield benefit" from the compound application had even surprised Kemira staff considering the fertility of the field via the soil analysis: pH 6.0, P 2, K 3 and Mg 2.