Simple Nitrogen Spreading Calculator

Do not leave any fields blank (if ‘none’ put ‘0’).

‘Total N/ha’ is the relevant number for the NVZ ‘Field Limit’ calculation: this works in terms of total N. The field limit only applies to organic manures, so don’t include any manufactured fertiliser in that calculation.

‘Crop available N/ha’ is the relevant number for any RB209 recommendations, as well as the N-Max calculation and any ‘low input’ Countryside Stewardship schemes (and similar): these work in terms of kg of N from manufactured fertiliser and kg of crop available N from organic manures.

All calculations are made according to DEFRA’s ‘NVZ guidance blank completion data tables‘ or else the ‘typical’ values as stated in the AHDB’s ‘Nutrient Management Guide (RB209)‘, correct as of 16/9/2025.

All calculations are really only rough estimates, even when based on the official values. Crop availability in particular is an estimate that has a significant margin for error: these results should be understood as an approximation only.