Crop farming · Fertilizer
Fertilizer blend rate and cost.
Enter the pounds of N, P2O5 and K2O per acre you want and the blend analysis. Get the product rate, what each nutrient comes to, and cost per acre and for the field.
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Blend rate and cost
Enter the values.
How much fertilizer blend per acre?
Product needed for one nutrient = pounds of nutrient wanted ÷ the analysis as a decimal. A blend carries all its nutrients in fixed proportions, so the rate that meets the largest requirement is the rate that meets all of them; the others come out equal to or above target. Cost per acre = pounds of product ÷ 2,000 × price per ton. The per-ton arithmetic (pounds of nutrient = 2,000 × analysis percent, then cost = price ÷ pounds) is the Purdue University Extension method.
Worked example. Target 30 lb N, 48 lb P2O5, 48 lb K2O per acre with a 12-24-24 blend at $520 per ton. N needs 30 ÷ 0.12 = 250 lb of product; P2O5 needs 48 ÷ 0.24 = 200 lb; K2O needs 200 lb. N sets the rate, so apply 250 lb per acre. That delivers 30 N, 60 P2O5 and 60 K2O, 12 lb more of each of the last two than wanted. Cost is 250 ÷ 2,000 × $520 = $65 per acre, and 80 acres takes 10 tons for $5,200.
When the blend does not fit. If one nutrient overshoots a lot, that over-application costs money and may exceed a recommendation or a local rule. A different analysis, or a straight-nitrogen product for the nitrogen-heavy part, may match the recommendation better. The cost-per-pound-of-nutrient tool on this site helps you compare them. The tool refuses a blend that has 0 percent of a nutrient you asked for.
Frequently asked questions
How many pounds of 12-24-24 do I need per acre?
Divide each nutrient target by its analysis and use the largest result. For 30-48-48 that is 250 lb, set by N (30 divided by 0.12).
Why does the blend over-apply some nutrients?
A blend has fixed proportions of N, P2O5 and K2O. When the crop's needs are in a different ratio, meeting the biggest need leaves the others over target.
What is the cost of fertilizer per acre?
Product rate in pounds per acre, divided by 2,000, times the price per ton. 250 lb of a $520 per ton blend is $65 per acre.
Where do I get the target pounds per acre?
From a soil test recommendation or a crop plan from your agronomist or extension office. This tool does not recommend rates.
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Not professional advice
Arithmetic only, not a fertilizer recommendation. Rates should come from soil testing and local guidance, and some jurisdictions limit nitrogen and phosphorus application. Follow the product label and handle fertilizer safely.