P & K Calculator

p&kcalculatorThe P & K calculator is an online calculator for estimating P and K fertilizer requirements for grassland and crops.

It is available online, or via the iOS and Android Smart Phone Apps.

It requires details of crop yield, grassland stocking rate, concentrate feed usage, soil test results, and slurry application to estimate chemical fertilizer P and K requirements.

All calculations are consistent with Best Practice Recommendations from Teagasc.



The P and K Calculator was developed by the Fertilizer Association of Ireland in Association with Teagasc and K+S UK & Eire Ltd.

K + S Teagasc


This P and K calculator tool provides general guidelines for crop offtake and/or general agronomic advice for P and K application to grassland and arable crops in Ireland.

For more detailed information, see Teagasc Nutrient Advice.

The guidelines included for crop requirement and organic fertilizer value may result in recommendations that exceed the maximum N and P allowances on the farm.

Fertilizer usage must be in compliance with Nitrates Regulations and other nutrient management legislation. This may constrain the rates of N and P fertilizer that are permissible relative to the guidelines shown by this tool.

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