keep it going in the right direction iggy-I've searched for a comparable fert pricing mechanism a couple times without sucess- however this article-emphasis added- suggests the costs /ton of some major ferts are 300/ton or more-which is about what bingo suggested CWRN's fert was worth-even without further onsite processing-see bingos 9-8-12 post
june 2012 CWRN indicated 200,000 tons of waste byproduct to be processed by the trommel, of which ca 135,000 tons are apparently fert-see my sticky article on trommel calcs at the end
no. 0.548 |
Fertilizer Cost Calculations
by K.A. Barbarick and D.G. Westfall 1 (1/07)
Quick Facts...
- A guaranteed analysis must be given for every fertilizer material sold in Colorado.
- The analysis includes the percentages of nitrogen, phosphorus, potassium and other plant nutrients present in quantities large enough to conform to state law.
- The cost per pound of nutrient is a major criterion in selecting a fertilizer.
The Colorado fertilizer law requires that the guaranteed analysis of every fertilizer material sold in the state be given on the face or display side of the container. The guaranteed analysis provides the percentage of nitrogen (N), available phosphorus (expressed as percent P 2 O 5 ), water soluble potassium (expressed as percent K 2 O) and other nutrients present in quantities that conform to state law.
The Commercial Fertilizer, Soil Conditioner, Plant Amendment and Agricultural Liming Materials Act of 1977 sets minimum nutrient content levels for the guaranteed analysis. Any commercial fertilizer for agricultural use primarily for nitrogen, phosphorous and potassium must contain a minimum total of 20 units of N-P 2 O 5 -K 2 O. For other nutrients, the fertilizer must guarantee the minimum amounts shown in Table 1 in order to be registered for sale in Colorado.
Even though the guaranteed analysis expresses phosphorus and potassium on the oxide basis, these plant nutrients occur in the fertilizer as mixtures of different chemicals. For example, the chemical formula for diammonium phosphate is (NH 4 ) 2 HPO 4 . It has a guaranteed analysis of 18-46-0 expressed as 18 percent N, 46 percent P 2 O 5 and 0 percent K 2 O, but actually contains no P 2 O 5 . The use of the oxide expression for plant nutrient content is a carry-over from early practices when chemists ignited fertilizer samples and weighed the oxides.
If the cost per pound of elemental P or K is desired, then the guarantee must be changed from P 2 O 5 to P and/or K 2 O to K. To find the conversion factor, use the ratio of the molecular weight of (2 x P) and divide by the molecular weight of P 2 O 5 . A similar approach is used for K. No conversion is needed for N since it is already expressed on an elemental basis. These conversions are:
Equation (1): P = P 2 O 5 / 2.29
Equation (2): P 2 O 5 = 2.29 x P
Equation (3): K = K 2 O / 1.21
Equation (4): K 2 O = 1.21 x K
| Table 1: Minimum nutrient concentration standard for fertilizer sold in Colorado. | |
| Element | Percent |
| Calcium (Ca) | 1.00 |
| Magnesium (Mg) | 0.50 |
| Sulfur (S) | 1.00 |
| Boron (B) | 0.02 |
| Copper (Cu) | 0.05 |
| Iron (Fe) | 0.10 |
| Manganese (Mn) | 0.50 |
| Molybdenum (Mo) | 0.0005 |
| Zinc (Zn) | 0.05 |
Single-Nutrient Fertilizers
The calculation of the cost of a pound of a nutrient in a fertilizer that contains a single element fertilizer is relatively simple. The costs in the following examples are for illustration only and do not reflect what the cost should be.
Urea, CO(NH 2 ) 2 , has a guaranteed analysis of 45-0-0 and costs $300 per ton. What is the cost per pound of N?
- First, calculate the pounds of N in the fertilizer:
2,000 lbs fertilizer x 0.45 = 900 lbs N. - Next, calculate the cost per pound of N:
$300 / 900 lbs N = $.33/lb N.
Superphosphate (0-46-0) costs $280 per ton. What is the cost per pound of P 2 O 5 ?
- First, calculate the pounds of P 2 O 5 in the fertilizer:
2,000 lbs fertilizer x 0.46 = 920 lbs. - Next, calculate the cost per pound of P 2 O 5 :
$280 / 920 lbs = $.30/lb P 2 O 5 .
What is the cost per pound of P in the superphosphate example above? There were 920 pounds of P 2 O 5 in one ton of superphosphate. If equation (1) is used, the cost per pound of P can be found.
- First, correct pounds of P 2 O 5 to pounds of P:
Lbs P = 920 / 2.29 = 402 lbs P. - Next, calculate the cost per pound of P:
$280 / 402 lbs P = $0.70/lb P.
Use similar procedures for any fertilizer that contains one plant nutrient.
Mixed Fertilizers
Mixed fertilizers contain more than one nutrient. An example is granulated diammonium phosphate (18-46-0) (DAP).
Assume DAP costs $320/ton. c alculate the cost of the P 2 O 5 in this fertilizer. Assume a cost per pound of N and the cost of the P 2 O 5 can be calculated. Assume the cost of the N is the same as 45-0-0 in the first example,or $.33/lb N. What is the cost of the P 2 O 5 in 18-46-0?
- First, calculate the pounds of N and P 2 O 5 in a ton of fertilizer:
2,000 lbs fertilizer x 0.18 N = 360 lbs N.
2,000 lbs fertilizer x 0.46 P = 920 lbs P 2 O 5 . - Next, calculate the cost of the fertilizer that can be attributed to the N:
$.33/lb N x 360 lbs N = $118.80. - Therefore, the total cost of the P 2 O 5 in the fertilizer is:
$320 - $118.80 = $201.20. - Finally, the cost of the P 2 O 5 is:
$201.20 / 920 lbs = $.22/lb P 2 O 5 .
Compare the cost for P 2 O 5 to other P 2 O 5 sources. Notice that the cost of the P 2 O 5 in 18-46-0 is substantially less than the cost of P 2 O 5 in 0-46-0 in the second example.
