Phosphate use has fallen to its lowest level in almost 40 years, with just 57% of arable crops receiving the nutrient in 2006, figures from the British Survey of Fertiliser Practice show.

The average application rate on winter wheat was just 31kg/ha, says Yara’s Mike Tucker, and potash use averaged just 41kg/ha. A typical crop, where straw is removed, takes off 73kg/ha and 100kg/ha of phosphate and potash respectively, he adds.

“Evidence suggests that many farms are putting their crops at risk of deficiency. Where soil reserves are clearly being mined, it is essential to use soil analysis to ensure that critical levels are not breached.”