Crop Yield vs. Fertilizer ROI Calculator

Economic optimum nitrogen rate (EONR) and marginal ROI for cereal, oilseed and root crops — models the yield-response curve and stops at the point where the last kg of N no longer pays for itself.

Zero-N baseline yield (t/ha)

Attainable maximum yield (t/ha)

Crop price (€/tonne)

Fertilizer cost (€/kg N)Ammonium nitrate 34.5% N at €430/t ≈ €1.25/kg N.

Response steepness kWheat 0.010–0.014, OSR 0.008, maize 0.007. Higher = faster plateau.

Field area (ha)

Result

Economic optimum N rate (EONR): 204 kg N/ha
Predicted yield at EONR: 9.03 t/ha
Yield gain over baseline: 5.03 t/ha
Extra revenue: €1,106/ha
Fertilizer bill: €255/ha
Net margin from fertilizing: €850/ha
Whole-field margin: €34,015/yr (40 ha)

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