OPTIMISING output from each field is the farming philosophy applied on 163ha (403-acre) Manor Farm at Eddlesthorpe, an all arable unit on the edge of the Yorkshire Wolds near Malton.
Managed by crop input distributor Independent Agriculture, the farms policy on nitrogen use is determined by readings of soil nitrate levels gathered at regular intervals using the Solomon system.
Reflectometer readings of soil water samples drawn from suction lysimeters every 10 days give a clear picture of soil nitrogen reserves and enable bag nitrogen to be applied when it is needed by the crop.
"Using the system does not necessarily lead to savings," says IAs Chris Rigley. "But it does ensure nitrogen is available in the required quantity when it is needed to optimise output."
Typical nitrogen use is 170-175kg/ha (136-140 units/acre) for winter wheat and 200kg/ha (160 units/acre) on oilseed rape, split into three applications. Smaller quantities applied more frequently would be ludicrous, says Mr Rigley.
The Solomon system is having important environmental effects by avoiding leaching of excess nitrogen into ponds and water courses, he adds.
Both are regularly tested and the highest nitrate reading recorded from drainage water has been 40ppm against a drinking water limit of 50ppm.
Having created 3m and 6m buffer zones under the Countryside Stewardship scheme care is taken not to spin nitrogen on to headlands and into hedge bottoms.
Precision use of fertiliser is easy if you know the nitrogen content of soil water, says Chris Rigely, farm manager for Independent Agriculture at Eddlethorpe, Yorks.
• Manages 163ha farm on Yorks Wolds for Independent Agriculture.
• Soil nitrogen test kit used to optimise fertiliser use.
• Water checks show minimal leaching or run-off.