Fertilizer NPK
Blend two grades to hit a target N-P-K ratio and total nutrient mass.
How to use this tool
Work out how to mix two off-the-shelf fertilizer grades to deliver a target amount of nutrients. Enter the two grades and what you need, and it gives the kilograms of each to combine.
What to enter
- Grade A / Grade B: the analysis printed on each bag as N-P₂O₅-K₂O percentages, e.g. urea is 46-0-0, muriate of potash (MOP) is 0-0-60.
- Target: the nutrient mass you want to deliver, in kg of N, P₂O₅ and K₂O.
Reading the result
You get the kilograms of each grade to blend, the total mass, the resulting N-P-K analysis, and the nutrients actually delivered. If two grades can't hit the target exactly (it would need a negative amount), the nearest workable blend is shown instead.
Worked example
To deliver 20 kg N and 20 kg K₂O from urea (46-0-0) and MOP (0-0-60), blend ≈ 43.48 kg urea with ≈ 33.33 kg MOP, 76.81 kg total.
Blend
The two figures are the kilograms of each grade to weigh out; the total and its N-P-K analysis describe the finished mix, and "delivers" confirms the nutrient mass it supplies. Two grades can independently hit only two nutrient targets, if the exact target would need a negative amount, the closest non-negative blend is shown instead.
Two-grade blending
Fertilizer grades are labelled N-P-K as percent of total weight (P as P₂O₅, K as K₂O by convention). To hit a target nutrient mass, this tool solves how many kg of each of two grades to combine. It reports the resulting N, P₂O₅ and K₂O delivered and the analysis of the final blend. If the target can't be met by these two grades, the nearest feasible blend is shown.
Sources
- IFA fertilizer handbook; standard agronomy blending (mass-balance on N, P₂O₅, K₂O).