11 December 1998

Check on nutrients

THE true cost to a dairy farmer of a tonne of nitrogen fertiliser could be £300 rather than the quoted price of £100 because only a third of the input is recovered in output.

The figures were given at the British Grassland Society winter meeting in Peebles last week by Alex Sinclair from SAC. He urged farmers to use soil nutrient budgets and measure inputs against outputs.

"Although the Ythan catchment area in Aberdeenshire was not given nitrogen vulnerable status, the inquiry gave us government funds to gather data which has proved highly valuable and points to the merits of nutrient budgets," said Dr Sinclair.

The data showed that cereal farms were most efficient at turning 67% of nitrogen inputs into outputs, followed by lowground cattle and sheep at 61%, general cropping at 59%, and pig farms at 52%. But dairy farm efficiency was only 34%, and LFA beef and sheep units came lowest of all at 23%, he told delegates.

"Farm gate nutrient budgeting has shown that there is scope for reducing fertiliser costs and there is more scope on some farm types than others," said Dr Sinclair.

"We need to raise the awareness of nutrient budgeting. The benefits are reduced fertiliser bills and greater access to quality assurance schemes which will increasingly demand traceability right down to the amount of fertiliser used in both grain and livestock systems," he added.

However, there would be increased costs in both recording and improved storage and handling systems for farm manures. Research at SAC had shown that, on economic grounds, neither an increased slurry store nor injection rather than surface spreading could be justified in terms of savings in fertiliser costs.