LEVELS OF potash in UK soils are continuing to fall, according to latest fertiliser usage figures – a trend dating back to 1993.

The Agricultural Industries Confederation‘s Survey of Fertiliser Practice, compares fertiliser usage against the requirements for various crops – taking into account crop type, area and yield.

Reducing fertiliser inputs to cut costs is a major factor in the decline, but this could have implications for future yields and farm profitability, warned Mike Armstrong of the Potash Development Association (PDA).

In recent years growers have tried to make cost savings by omitting potash from their fertiliser policy, he said.

“If the soil index for potash is sufficiently high (index 3 and above) this is a sensible option.

“But evidence suggests that this practice is being carried out on fields with low K reserves, where crop yields will suffer if potash is not applied at the correct level.”

Sometimes the decision to omit potash is taken on fields where soil analyses have not even been done, he added.

Farmers should soil sample their fields and apply potash fertiliser based on this analysis and crop offtake, Mr Armstrong said.

Up to a third of UK arable land has low levels of potash, he believes.

“Fertiliser manufacturers will need to rethink their products, as there is a need for less phosphate and more potash,” he concluded.