Monopotassium phosphate MKP on 20 m² — 384.6 g for 10 g/m² of P₂O₅
To put 10 g/m² of P₂O₅ on 20 m² with Monopotassium phosphate MKP, spread 384.6 g — that is 19.23 g per m². At 52% content it is simply the 200 g of nutrient you need divided by that figure.
Fertilizer to spread
Urea is only 46% nitrogen, so putting 10 g of N down means spreading 10 ÷ 0.46 = 21.74 g of urea. Multiply instead and you get 4.6 g, a number that looks plausible enough to pass unnoticed. Whenever the content is below 100%, the fertilizer weight is always larger than the nutrient weight — that is the fastest check that you have the division the right way round.
- P₂O₅ 5 g/m² · 9.62 g/m²192.3 g
- P₂O₅ 10 g/m² · 19.23 g/m²384.6 g
- P₂O₅ 15 g/m² · 28.85 g/m²576.9 g
- P₂O₅ 20 g/m² · 38.46 g/m²769.2 g
Comes along with it
Matching 10 g/m² of N with a 21-17-17 puts the fertilizer at 47.62 g/m², and those 47.62 g carry 8.1 g of P₂O₅ and 8.1 g of K₂O with them. You do not get to choose: once the fertilizer weight is fixed, the other two are dragged along in proportion to their content. That is why one compound bag rarely hits all three targets. The order of work is to match one, then top up or accept the surplus with straight fertilizers.
- K₂O 34% · 6.54 g/m²130.8 gK 108.5 g
- Fertilizer
- Monopotassium phosphate MKP (0-52-34)
- Area
- 20 m²
- Nutrient matched
- P₂O₅
- Content
- 52%
- Nutrient needed
- 200 g
- Per m²
- 19.23 g
Nearby cells
Same fertilizer, other areas
Same area, other fertilizers
Worth knowing
- Fertilizer to spread = nutrient needed ÷ (content ÷ 100). It is a division, never a multiplication.
- Nutrient needed = area × target rate, so twice the area means twice the fertilizer.
- A fertilizer with half the content takes twice as much for the same nutrient — inverse proportion.
- With a compound, matching one nutrient drags the other two in at their content ratio.
Common questions
Q. How much Monopotassium phosphate MKP goes on 20 m²?
At 10 g/m² of P₂O₅, 384.6 g — that is 19.23 g per m². It is the 200 g of nutrient needed divided by the 52% content.
Q. If I double the target, do I double the fertilizer?
Yes. Target and fertilizer weight are directly proportional — 5 g/m² takes 192.3 g and 20 g/m² takes 769.2 g. Area behaves the same way: twice the area, twice the fertilizer.
Q. What else goes in along with it?
Matching P₂O₅ to the target also puts in K₂O 130.8 g. That is not a choice — those amounts are dragged in at their content ratio.