Crop farming · Fertilizer
Fertilizer cost per pound of nutrient.
Enter the analysis and the price per ton to get cost per pound of N, P2O5 or K2O, with a credit for the other nutrients in multi-nutrient products.
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Cost per pound
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How to calculate fertilizer cost per pound of nutrient
Compare fertilizers by the cost of the nutrient, not the cost of a ton of product. Pounds of nutrient per ton = 2,000 × the analysis percent. Cost per pound = price per ton ÷ pounds of nutrient per ton. The analysis on the bag lists percent nitrogen (N), phosphate (P2O5) and potash (K2O). Purdue University Extension (R.L. Nielsen) sets out these steps.
Worked example, single nutrient. Anhydrous ammonia 82-0-0 at $285 per ton holds 2,000 × 0.82 = 1,640 lb of N, so N costs 285 ÷ 1,640 = $0.174 per lb (Purdue: 17 cents). Liquid 28% UAN at $225 per ton holds 560 lb of N, so N costs $0.402 per lb (Purdue: 40 cents).
Worked example, blend. For 10-34-0 at $260 per ton, the P2O5 is 680 lb and N is 200 lb. Purdue values the phosphate at the price of 0-46-0 at $260 per ton, which is about 28 cents per lb. The phosphate credit is 680 × $0.28 = $190.40, leaving $69.60 for the N, or 69.60 ÷ 200 = $0.348 per lb of N (Purdue rounds this to 35 cents). That makes it cheaper N than 28% UAN, but you are also buying phosphorus, so the credit only helps when the crop needs the phosphorus.
The analysis values for urea (46% N) and UAN solutions (28, 30 and 32% N) are described in a Virginia Cooperative Extension fact sheet on nitrogen sources. Enter local prices; the tool contains none. Per-acre cost is cost per lb of nutrient × pounds of that nutrient applied.
Frequently asked questions
How do I calculate the cost per pound of nitrogen in urea?
Urea is 46 percent N, so a short ton holds 920 lb of N. Divide your price per ton by 920. At $600 per ton that is about 65 cents per lb of N.
How do I compare anhydrous ammonia, urea and UAN?
Put each product's price per ton into the tool with its analysis (82-0-0, 46-0-0, 28-0-0) and compare the cost per pound of N. Also weigh application cost, losses and timing, which are not in the price.
How do I price a blend like 10-34-0?
Value the other nutrient at a reference price (Purdue uses the P2O5 price in 0-46-0), subtract it from the product price, and divide what is left by the pounds of the nutrient you want.
Does this work with metric tonnes?
Yes. Choose metric tonne and the tool uses 2,204.6 lb of product per tonne.
Sources
Checked
- Purdue University (R.L. Nielsen): Fertilizer Reckoning for the Mathematically Challenged
- Virginia Cooperative Extension: Nitrogen Fertilizer Sources and Properties
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Not professional advice
Arithmetic only. Fertilizer prices change daily and nutrient recommendations depend on soil tests, crop and local rules. Follow your agronomist, soil test report and any nutrient management regulations. Anhydrous ammonia is hazardous; follow the handling and PPE rules on the label and SDS.