Skip to content
ENExplore Calculators

Fertiliser Dose Per Acre Calculator

Work out fertiliser dose per acre instantly with clear inputs, formula shown and shareable results.

About Fertiliser Dose Per Acre Calculator

Recommendations are written as kilograms of N, P2O5 and K2O per hectare, but fertiliser is bought as products. DAP carries 46% P2O5 and 18% N, so it is sized on the phosphate need first and the nitrogen it supplies is deducted before the urea (46% N) balance is worked out. Potash comes from MOP at 60% K2O.

Formula

Product from nutrient

DAP = P2O5 need / 0.46; urea = (N need - 0.18 x DAP) / 0.46; MOP = K2O need / 0.60

Worked example

With the default values below, Fertiliser Dose Per Acre Calculator returns Urea Required of 419.66. Change any input above and every figure here is recalculated in your browser.

Inputs used

Areaminimum 0.01 ha
2 ha
Nitrogen Recommendationminimum 0 kg N/ha
120 kg N/ha
Phosphate Recommendationminimum 0 kg P2O5/ha
60 kg P2O5/ha
Potash Recommendationminimum 0 kg K2O/ha
40 kg K2O/ha

Results

Urea Required
419.66
DAP Required
260.87
Muriate Of Potash Required
133.33
Total Nutrient Applied
440.00

Step by step

  1. 1Values used
  2. 2Product from nutrient
  3. 3Urea Required= 419.66
  4. 4DAP Required= 260.87
  5. 5Muriate Of Potash Required= 133.33
  6. 6Total Nutrient Applied= 440.00

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Follow your state soil-test-based recommendation and label instructions. Over-application of nitrogen and phosphate causes groundwater and surface water pollution and may breach nutrient management rules.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Follow your state soil-test-based recommendation and label instructions. Over-application of nitrogen and phosphate causes groundwater and surface water pollution and may breach nutrient management rules.

Frequently Asked Questions

Why deduct nitrogen supplied by DAP?

DAP is 18% nitrogen. Ignoring it over-applies N, which wastes money, encourages lodging and leaches to groundwater.

Should the whole dose go on at sowing?

Phosphate and potash are usually applied as a basal dose. Nitrogen is normally split — around one third basal and the rest as two top dressings timed to tillering and panicle or flowering stages.

Related Calculators

Fertiliser Dose Per Acre Calculator | Calcrivo