Third tool in the Farming section, this one for working out fertiliser.
Most fertiliser calculators online are built for the American system, where phosphorus and potassium are quoted as oxides, P2O5 and K2O. South Africa labels everything in elemental form, plain N, P and K, and the oxide numbers are bigger for the same amount of actual nutrient. So if you take an international recommendation, or use one of those overseas calculators, and apply it here as if the numbers were the same, you quietly over-apply your P and K and waste money. This tool works in elemental N, P and K throughout, and there is a toggle to convert an oxide recommendation across properly if that is what you have.
Two things it does. The first tab is the straightforward one, pick your product, put in your area and rate and bag size, and it gives you the bags to buy, the total kilograms and the cost, plus what that actually feeds into the soil in kilograms of N, P and K. The second tab checks a plan against a soil test, you enter your target per hectare and add the products you are thinking of using, and it tells you whether the plan meets, falls short of, or overshoots each nutrient.
The number I think earns its keep is cost per kilogram of nutrient. Two bags at the same price are not equal value if one is half filler. Urea at 46 percent nitrogen versus LAN at 28 percent is the obvious one, on cost per kilogram of nitrogen urea usually works out a good bit cheaper even when the bag costs more, and the tool shows that gap straight away.
One thing it deliberately does not do is tell you how much to apply. The right rate depends on your soil, your crop and your yield goal, which is what a soil test is for, so the tool turns a rate you already have into bags and cost rather than inventing a recommendation. The reference prices are the bulk commodity figures from SA Grain for July 2026, retail bags cost more, so there is a field to type in your own quote.
If you buy fertiliser, I would value a sanity check. Do the grades and nutrient contents match what is on the bags you actually buy, and is the cost per kilogram of nutrient landing where you would expect against your own quotes. Happy to add grades or fix numbers if anyone spots something off.