App boasts easier P and K fertiliser rate calculations

A smartphone app is set to make it easier to calculate potash and phosphate fertiliser rates in different fields, thereby avoiding yield losses through deficiency.

Developed by the Potash Development Association (PDA), the PK Kalculator App first calculates P and K offtakes by most UK crops at harvest.

“Users simply enter the crop details and yield, click calculate and the app shows the offtake,” says the PDA.

See also: 7 essential arable farming apps
These quantities are often termed “maintenance dressings”, and usually provide the recommendation for fertiliser use when soil indices are at target level.


Farmers can make savings if the soil index is above the target level, cutting back on rates or by taking a P and K holiday.

However, if soil indices are below target, the second part of the app calculates how much nutrient is needed to correct the deficiency.

“Often the amount needed is more than that can reasonably be applied in one season,” says the association.

Therefore, the app asks users what timescale (how many years) they wish to rectify the soil deficiency and the calculator comes up with a plan.

The app is available for both Apple and Android smartphones and tablets.

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