This one we're genuinely excited about. Our new Fertiliser & Nutrient Calculator is live — and unlike every calculator of ours so far, it doesn't just follow the AHDB Nutrient Management Guide (RB209). It sends your field's details to AHDB's own RB209 calculation engine and shows you what comes back. The numbers on your screen are AHDB's numbers, not our reading of their tables.
What you put in, what you get out
You tell it the things you know off the top of your head: crop and end use, soil type, what grew there last year, your postcode (it looks up your average rainfall itself, from AHDB's own dataset), and whether you're in an NVZ — that's enough to get going. If you have a recent soil analysis, add the pH and your P, K and Mg indices and the recommendations sharpen accordingly.
Out comes the full nutrient plan for the crop: nitrogen, phosphate, potash, magnesium, sodium, sulphur and lime, each with the soil index it was based on — plus the RB209 advice notes that go with your situation, the same ones an adviser would point you to in the Guide.
No soil analysis? Still works
Here's the bit we like most: leave the analysis fields empty and the engine falls back to RB209's field assessment method — estimating your soil nitrogen supply from the previous crop, soil type and rainfall. That's exactly what the Guide tells you to do when you don't have a measurement. (It also politely declines to guess a lime rate without a measured pH, which is the right answer — for lime from a pH result, our Lime Requirement Calculator has you covered in ten seconds.)
Honest small print
Three things, said plainly, the way we try to say everything:
- It's a planning aid, not advice. The tool shows what the RB209 methodology recommends for the details you enter. Nutrient plans, NVZ compliance and product choice belong with a FACTS qualified adviser who knows your farm.
- Current scope is arable, England & Wales, one crop a year. Grassland is planned; Scotland depends on our licence with AHDB growing.
- It's free, and stays free for as long as our AHDB API access does. We're a zero-budget initiative on a trial licence; if the terms ever change, we'll say so on the tool page rather than quietly adding a paywall.
Where it fits
This is the eleventh free tool on the site, and it slots into a workflow with the others: check your fields from orbit with the NDVI viewer, work out the requirement here, and if you're liming, price the material with the lime calculator. All free, none of them need an account, and the ones that save records do it only if you want them to.
Try it, and tell us what it gets right and wrong — there's a star rating at the bottom of the page now, and we read it.
Sources
Recommendations are calculated by the AHDB RB209 Web API and reproduced with attribution. UKPAI is not affiliated with AHDB; we're a licensed API user.