Corn Fertilizer Calculator
Convert N-P-K nutrient recommendations into actual fertilizer products. Calculate urea, DAP, and potash rates per acre and total quantities needed.
Fertilizer Requirement Inputs
N-P-K recommendation per acre
Take multiple samples from different field locations and average them for the most accurate results. Avoid border rows and unusual spots.
All calculations use USDA-standard formulas. No registration required, works on mobile, tablet, and desktop.
What Is a Corn Fertilizer Calculator?
A corn fertilizer calculator converts N-P-K nutrient recommendations into actual fertilizer products and quantities. Whether you soil test through your local coop or use university recommendations, this calculator tells you exactly how much urea, DAP, potash, and other fertilizer products to apply per acre and in total.
Corn is a heavy feeder — a 200 bu/ac crop removes approximately 145 lb N, 60 lb P₂O₅, and 45 lb K₂O per acre. Replacing these nutrients is essential for maintaining soil test levels and sustaining yield. Under-fertilizing reduces yield; over-fertilizing wastes money and risks environmental loss.
This calculator uses common fertilizer grades: urea (46-0-0), DAP (18-46-0), and potash (0-0-60). It also accounts for the small amount of N supplied by DAP, ensuring your total N application is correct.
Common Fertilizer Grades
| Product | Grade (N-P-K) | Best For |
|---|---|---|
| Anhydrous Ammonia | 82-0-0 | Cheapest N source; fall/spring application |
| Urea | 46-0-0 | Dry N for spring or sidedress |
| UAN Solution | 32-0-0 or 28-0-0 | Liquid N for split application |
| Ammonium Sulfate | 21-0-0-24S | N + sulfur; good for no-till |
| DAP (Diammonium Phosphate) | 18-46-0 | P + some N; most common P source |
| MAP (Monoammonium Phosphate) | 11-52-0 | Higher P than DAP; lower N |
| Potash (Muriate of Potash) | 0-0-60 | Standard K source |
| Potassium Magnesium Sulfate | 0-0-22-11Mg-22S | K + Mg + S for deficient soils |
Corn Nutrient Removal Rates
Knowing what your crop removes helps you plan replacement:
Soil Testing: The Foundation of Fertilizer Planning
Don't guess — soil test. Fertilizer recommendations should be based on soil test results, not generic rates. Standard recommendations:
- Test every 2-4 years per field, more often on sandy or high-value ground
- Sample by soil type — don't mix sandy and clay samples
- Take 15-20 cores per 20-acre sample area
- Sample at consistent depth — 6-7 inches for conventional, 3-4 inches for no-till
- Use a reputable lab — university labs are cheapest; private labs often faster
Frequently Asked Questions
Everything you need to know about corn yield calculation
Corn typically needs 150-200 lb N, 60-100 lb P₂O₅, and 40-80 lb K₂O per acre, depending on soil test levels and yield goal. A 200 bu/ac crop removes about 145 lb N, 60 lb P₂O₅, and 45 lb K₂O. Soil testing determines exact replacement needs.
Most corn farmers use a combination: anhydrous ammonia (82-0-0) for cheapest N, DAP (18-46-0) for phosphorus, and potash (0-0-60) for potassium. Urea (46-0-0) or UAN (32-0-0) work for sidedress. Specific blends depend on soil test results.
Corn fertilizer costs $200-300 per acre for typical N-P-K program: 180 lb N at $0.60/lb = $108; 80 lb P₂O₅ at $0.70/lb = $56; 60 lb K₂O at $0.50/lb = $30; plus $20-40 micronutrients and application. Fertilizer is typically 25-30% of total corn production cost.
Phosphorus and potassium can be applied fall or spring before planting. Nitrogen should be split: 30-50% pre-plant (or fall anhydrous with inhibitor) and remainder as sidedress at V3-V8. Avoid fall N on sandy or wet soils to prevent leaching losses.
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