Ohio State University Extension Factsheet

Ohio State University Fact Sheet

Agriculture and Natural Resources

2120 Fyffe Road, Columbus, Ohio 43210-1084


Purchasing Nutrients for Hay and Forage Crops

ANR-7-99

Clif Little
Extension Agent
Agriculture/Natural Resources Agent
Guernsey County

Jeff McCutcheon
Extension Agent
Agriculture/Natural Resources Agent
Perry County

Fertilizer can be a significant out-of-pocket expense in the maintenance of hay and forage crops. Frequently, cost is given as the prime reason why a producer does not fertilize hay and forage crops for maintenance. Producers can save money on fertilizer applications if they compare the total cost of applying different fertilizer blends.

Cost of Applying a Single Nutrient

Economically speaking, all fertilizers are not created equal. Let's say you have decided that this year you want to stockpile a field of tall fescue for winter grazing. You remember a recommendation that you should apply 50 pounds of actual nitrogen per acre. The local fertilizer dealer gives you these prices on three different nitrogen sources:

Urea @ $190/ton
Ammonium Nitrate @ $240/ton
Ammonium Sulfate @ $167/ton

What fertilizer would be the best choice if you wanted to apply 50 pounds of nitrogen per acre? At first glance, you might choose Ammonium Sulfate. The actual value of each as a nitrogen source is quite different, as illustrated in this example:

  1. First, remember that each fertilizer is not 100 percent nitrogen. The percentage of the nutrients in each fertilizer is given in its guaranteed analysis. For example, a fertilizer with the analysis of 10-10-10 contains 10 percent nitrogen, 10 percent phosphate (P2O5), and 10 percent potash (K2O).
    The guaranteed analyses for the three available fertilizers are:

    Urea = 46-0-0
    Ammonium Nitrate = 34-0-0
    Ammonium Sulfate = 21-0-0-2

  2. Calculate the pounds of fertilizer per acre you must use to apply 50 pounds of nitrogen per acre (N/A). To do this, divide the amount of the nutrient wanted by the proportion of that nutrient in the fertilizer used.
    (Nutrient rate per acre ÷ fertilizer nutrient proportion = pounds of fertilizer needed to apply per acre.)

    Urea (46-0-0)
    50 lb. N per A ÷ 0.46/lb. of fertilizer = 109 pounds of fertilizer needed to apply per acre.

    Ammonium Nitrate (34-0-0)
    50 lb. N/A ÷ 0.34/lb. of fertilizer = 147 lb. of fertilizer pe racre to be applied.

    Ammonium Sulfate (21-0-0-2)
    50 lb. N/A ÷ 0.21/lb. of fertilizer = 238 lb. of fertilizer per acre to be applied.

    There is quite a difference in the amount of fertilizer you would need to apply. What does this mean economically?

  3. Calculate the number of acres per ton that each fertilizer will cover.
    (Pounds per ton ÷ pounds of fertilizer per acre = acres per ton.)

    Urea
    2,000 lb. per ton ÷ 109 lb. per acre = number of acres per ton or 18.3 acres per ton.

    Ammonium Nitrate
    2,000 lb./ton ÷ 147 lb. per acre = 13.6 acres per ton.

    Ammonium Sulfate
    2,000 lb./ton ÷ 238 lb. per acre = 8.4 acres per ton.

  4. Calculate the fertilizer cost per acre.
    (Commercial fertilizer cost per ton acres per ton = fertilizer cost per acre.)

    Urea @ $190 per ton
    $190 ÷ 18.3 acres per ton = $10.38 per acre.

    Ammonium Nitrate @ $240/ton
    $240 ÷ 13.6 = $17.65 per acre.

    Ammonium Sulfate @ $167/ton
    $167 ÷ 8.4 = $19.88 per acre.

    But material costs are only part of the total cost of applying the fertilizer.

  5. Calculate the spreading cost. Your cost may vary. This calculation uses a spreading cost of $6.00 per ton, the cost to rent the local spreader.
    (Spreading cost per ton acres per ton = spreading cost per acre.)

    Urea
    $6.00/ton ÷ 18.3 acres/ton = $0.33 spreading cost/acre.

    Ammonium Nitrate
    $6.00 ÷ 13.6 = $0.44 spreading cost/acre.

    Ammonium Sulfate
    $6.00 ÷ 8.4 = $0.71 spreading cost/acre.

  6. Now calculate the total cost for each fertilizer.
    (Fertilizer cost per acre + spreading cost per acre = total cost for each fertilizer per acre.)

    Urea total cost per acre =
    $10.38 fertilizer cost/acre + $0.33 spreading cost/acre =$10.71 per acre.

    Ammonium Nitrate total cost per acre =
    $17.65 fertilizer cost/acre + $0.44 spreading cost/acre =$18.09 per acre.

    Ammonium Sulfate total cost per acre =
    $19.88 fertilizer cost/acre + $0.71 spreading cost/acre =$20.59 per acre.

    If you had 50 acres, then it would cost:
    Urea: $10.71 x 50 = $535.50
    Ammonium Nitrate: $18.09 x 50 = $904.50
    Ammonium Sulfate: $20.59 x 50 = $1,029.50

In this case, urea was actually the best value. This was an example to demonstrate the steps in determining what the total cost of applying a given fertilizer would be. Please remember that applications of urea-based fertilizers in summer may result in significant losses of nitrogen due to volatilization. If one-half inch of rain is not received in three to four days after an application of urea, then volatilization of the urea can be significant. For more information on proper use of nitrogen fertilizers, please refer to Selecting Forms of Nitrogen Fertilizer, Agronomy Fact Sheet 205. Using these steps to compare fertilizer cost may save producers hundreds, if not thousands, of dollars annually. Fertilizing when plants can best utilize nutrients, managing your nitrogen source, and comparing the total cost of fertilizer blends will put more money in your pocket. It should be noted that the calculations presented here do not consider the value of other nutrients available in these fertilizer blends. If you are fertilizing for multiple nutrients, then the same process can be used.

Cost of Mixed Fertilizers

The previous example was for one nutrient, and each of the choices had one nutrient to compare. How can you compare mixed blends of fertilizer? Compare the following different fertilizer sources:

15-15-15 @ $210.72/ton

19-19-19 @ $220.60/ton

What fertilizer would be the best choice?

  1. First calculate the pounds of nutrients in a ton of fertilizer. To do this, add the percentage of nutrients together and multiply a ton by the sum.
    (2,000 lb. per ton x total percent nutrients = pound of nutrients in a ton of fertilizer.)

    15-15-15
    2,000 lb./ton x (0.15 + 0.15 + 0.15) = 900 lb. of nutrients in a ton of 15-15-15.

    19-19-19
    2,000 lb./ton x (0.19 + 0.19 + 0.19) = 1,140 lb. of nutrients in a ton of 19-19-19.

    There is quite a difference in the amount of nutrients you receive per ton of fertilizer. What does this mean economically?

  2. Next calculate the cost per pound of nutrients in each fertilizer. This can be done by dividing the cost per ton of fertilizer by the pounds of nutrients per ton.
    (Cost per ton ÷ pounds of nutrient per ton = cost per pound of nutrient.

    15-15-15
    $210.72 per ton ÷ 900 lb. of nutrient per ton = $0.23 per lb. of nutrient.

    19-19-19
    $220.60/ton ÷ 1,140 lb. of nutrient/ton = $0.19 per lb. of nutrient.

    In this example, 19-19-19 would be the better value. This method works as a basic comparison of multiple nutrient fertilizers, but does not take into account any difference in price between the different nutrients. This method can also be used to compare single nutrient fertilizers.

Calculating Fertilizer Cost Based on Soil-Test Results

Rarely do crops need the three primary nutrients on a one- to-one-to-one basis. It is recommended that a soil-test analysis and possibly a tissue analysis be utilized to determine the crop's needs for nutrients and the rates at which those nutrients should be applied. A soil test is the best way to determine the nutrient needs of a soil. Several laboratories in and around Ohio offer soil-testing services for a nominal fee. Contact your local Extension office for a complete list. Please refer to Bulletin E-2567 or Fact Sheet AGF 206-95 for information on correct sampling procedures.

Soil tests provide information about the nutrient level of the soil and the amounts of lime and fertilizers necessary to achieve a particular yield goal. In addition, educational comments for particular crops are provided on the report form.

What happens after you have taken a soil test and have the results? How do you determine the best fertilizer to apply? Let's look at a soil-test report that came from a field at the Eastern Ohio Resource Development Center (EORDC). This is a field of fescue with a yield goal of three tons per acre. The results say that this year we need to apply:

125 pounds of nitrogen, 50 pounds of phosphate, and 265 pounds of potash per acre.

The results also say that we should split the nitrogen application into a spring and a fall treatment. Since you need to split the nitrogen application, you decide to split the phosphate and potash application as well. Now you will need to apply:

62.5 pounds of nitrogen, 25 pounds of phosphate, and 132.5 pounds of potash per acre in the spring and in the fall. To avoid the potential for grass tetany, you decide to apply the spring application after first cutting.

You call the local fertilizer dealer and get the following prices.

  19-19-19 @ $220.60/ton
Urea 46-0-0 @ $190.00/ton
Triple Super Phosphate 0-46-0 @ $249.90/ton
Potash 0-0-60 @ $187.00/ton
DAP 18-46-0 @ $265.00/ton

What would be the best choice or combination to use?

  1. Since phosphate is the smallest amount we need to apply and we don't want to over apply any nutrient, let's look at it first. We need 25 pounds of phosphate per acre. Three sources are available to supply that amount.

    19-19-19
    0-46-0
    18-46-0

  2. First, calculate how much of each fertilizer is needed to supply 25 pounds of phosphate. To do this, divide the amount of the nutrient wanted by the proportion of that nutrient in the fertilizer used.
    (Nutrient rate per acre ÷ fertilizer nutrient proportion = pounds of fertilizer needed to apply per acre.)

    19-19-19
    25 lb. P205/A ÷ 0.19/lb. of fertilizer = 131.6 lb. of fertilizer per acre.

    0-46-0
    25 lb. P205/A ÷ 0.46/lb. of fertilizer = 54.3 lb. of fertilizer per acre.

    18-46-0
    25 lb. P205/A ÷ 0.46/lb. of fertilizer = 54.3 lb. of fertilizer per acre.

  3. Next calculate how much other nutrients we are supplying with these sources of phosphate. To do this, we multiply the pounds of fertilizer per acre that must be applied by the proportion of the other nutrients in that fertilizer.
    (Pounds of fertilizer that must be applied for correct rate of phosphate x proportion of other nutrients in blend = pounds of other nutrients we are applying.)

    19-19-19
    131.6 lb. x 0.19 (N) = 25 lb. of N applied per acre.
    131.6 lb. x 0.19 (K2O) = 25 lb. of K2O applied per acre.

    0-46-0
    No other nutrients being applied.

    18-46-0
    54.3 lb. x 0.18 (N) = 9.8 lb. of N applied per acre.

  4. Next, calculate the pounds of fertilizer you must use to apply the recommended rate of nitrogen per acre. The single nitrogen source is urea, 46-0-0. Remember to subtract the amount applied from other sources.
    (Nutrient rate per acre - amount from other sources ÷ fertilizer nutrient proportion = pounds of fertilizer you need to apply per acre.)

    19-19-19 + 46-0-0
    62.5 lb. N/A - 25 lb. applied ÷ 0.46/lb. of fertilizer = 81.52 lb. of urea per acre must be applied.

    0-46-0 + 46-0-0
    62.5 lb. N/A ÷ 0.46/lb. of fertilizer = 135.9 lb. of urea needed to apply per acre.

    18-46-0 + 46-0-0
    62.5 lb. N/A - 9.8 lb. applied ÷ 0.46/lb. of fertilizer = 114.6 lb. of urea needed to apply per acre.

  5. Now calculate the pounds of fertilizer you must use to apply the recommended rate of potash per acre. The single potash source is 0-0-60. Remember to subtract the amount applied from other sources.
    (Nutrient rate per acre recommended - amount from other sources ÷ fertilizer nutrient proportion = pounds of fertilizer needed to apply per acre.)

    19-19-19 + 46-0-0 + 0-0-60
    132.5 lb. K/A - 25 lb. applied ÷ 0.60/lb. of fertilizer = 179.2 lb. of potash per acre must be applied.

    0-46-0 + 46-0-0 + 0-0-60
    132.5 lb. K/A ÷ 0.60/lb. of fertilizer = 220.8 lb. of potash needed to apply per acre.

    18-46-0 + 46-0-0 + 0-0-60
    132.5 lb. K/A ÷ 0.60/lb. of fertilizer = 220.8 lb. of potash needed to apply per acre.

  6. Finally, calculate the cost per acre to apply each fertilizer blend. To do this, calculate the sum of the cost per pound of each ingredient multiplied by the pounds needed for that ingredient.
    (Cost for ingredient per ton ÷ 2,000 lb. per ton x number of pounds needed to apply.) Repeat this for each ingredient purchased and total as shown in the example given here.

      19-19-19 @ $220.60/ton
    Urea 46-0-0 @ $190.00/ton
    Triple Super Phosphate 0-46-0 @ $249.90/ton
    Potash 0-0-60 @ $187.00/ton
    DAP 18-46-0 @ $265.00/ton

    19-19-19 + 46-0-0 + 0-0-60
    (($220.60 ÷ 2,000) x 131.6) + (($190 ÷ 2,000) x 81.52) +
    (($187 ÷ 2,000) x 179.2) = $39.50 per acre.

    0-46-0 + 46-0-0 + 0-0-60
    (($249.90 ÷ 2,000) x 54.3) + (($190 ÷ 2,000) x 135.9) +
    (($187 ÷ 2,000) x 220.8) = $40.33 per acre.

    18-46-0 + 46-0-0 + 0-0-60
    (($265 ÷ 2,000) x 54.3) + (($190 ÷ 2,000) x 114.6) +
    (($187 ÷ 2,000) x 220.8) = $38.71 per acre.

    In this example, using a blend of DAP (18-46-0), urea (46-0-0), and potash (0-0-60) was the most economical. Prices listed in this fact sheet were current at the time of writing. Prices of fertilizer will vary. However, you may use the formulas regardless of price change. The calculations presented here do not take into account blending cost. When purchasing fertilizer, consider sources of macronutrients and micronutrients found in common fertilizer materials. Table 1 lists common sources of fertilizers and approximate contents.

    Table 1. Percentage of Fertilizer Nutrients and Content

    Source N P2O5 K2O Secondary & Micronutrients
    With Concentrations Greater Than 1%
    Anhydrous Ammonia
    82.0
    -
    -
    -
    Ammonia Nitrate
    33.5
    -
    -
    Ammonia Sulfate
    21.0
    -
    -
    23.0 S
    Urea
    46.0
    -
    -
    -
    Aqua Ammonia
    20.0-25.0
    -
    -
    -
    Nitrogen Solutions
    20.0-32.0
    -
    -
    -
    Urea Formaldehyde
    38.0
    -
    -
    -
    Calcium Nitrate
    15.5
    -
    -
    19.4 Ca, 1.5 Mg
    Superphosphate
    -
    47.0
    -
    14.0 Ca, 1.4 S
    Ammonia Phosphate
    11.0
    48.0
    0.2
    1.1 Ca, 2.2 S
    Diammonium Phosphate
    18.0
    47.0
    -
    Muriate of Potash
    -
    -
    60.0-62.0
    47 Cl, 1.2 Mg, 18.0 S
    Potassium Magnesium Sulfate
    -
    -
    21.0
    11.0 Mg, 23.0 S
    Potassium Nitrate
    13.0
    -
    44.0
    Ammonium Nitrate-lime
    20.0
    -
    -
    7.3 Ca, 4.4 Mg, 4.0 S
    Magnesium Sulfate
    -
    -
    -
    2.2 Ca, 10.5 Mg, 14.0 S
    Gypsum (Calcium Sulfate)
    -
    -
    0.5
    22.3 Ca, 17.0 S
    Elemental Sulfur
    -
    -
    -
    30.0-99.0 S
    Basic Slag
    -
    8.0-12.0
    29.0 Ca, 3.3 Mg, 21.0 Mn
    Kieserite
    -
    -
    -
    1.5 Ca, 18.2 Mg
    Dolomite
    -
    -
    -
    21.0 Ca, 18.2 Mg
    Limestone (calcitic)
    -
    -
    0.3
    32.0 Ca, 3.0 Mg
    Borax
    -
    -
    -
    11.0 B
    Copper Sulfate
    -
    -
    -
    33.0 Cu, 13.0 S
    Iron Sulfate
    -
    -
    -
    20.0 Fe, 12.0 S
    Manganese Oxide
    -
    -
    -
    41.0-68.0 Mn
    Manganese Sulfate
    -
    -
    -
    23.0-28.0 Mn, 13.0 S
    Zinc Oxide
    -
    -
    -
    50.0-80.0 Zn
    Zinc Sulfate
    -
    -
    -
    12.0-18.0 Zn
    Source: The Fertilizer Handbook, by The Fertilizer Institute, Washington, D.C.

The decision as to what nutrients to purchase for forage crops should be based on soil and possibly tissue tests. Differences in the value of crop nutrients can be extreme. For this reason, we recommend that you purchase the nutrients needed as indicated through proper analysis. Compare each nutrient source for the concentration of nutrients and follow the best management practices associated with the application of nutrients described in OSU Extension Bulletin 609. If planting, the amount of nitrogen supplied by the previous crop should also be considered. Table 2 lists nitrogen credits that should be subtracted from the nitrogen fertilizer recommendation if not previously done by the soil testing laboratory.

Table2. Nitrogen Available from Previous Crop (lb/acre)

Previous Crop N Credits
Corn, Small Grain 0
Soybeans 30
Grass Sod/Pasture 40
Forage Legume  
Avg. Stand (3 plants/ft2) 40 + [20 x (plants/ft2)]
  Max. 140
Source: Extension Bulletin E-2567

For more information on forage fertility or if you have specific questions on testing, contact your local Extension office.

Bibliography

Michigan State University, The Ohio State University, Purdue University. Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat & Alfalfa. Extension Bulletin E-2567.

Potash & Phosphate Institute. 1996. Soil Fertility Manual. Norcross, Georgia.

The Fertilizer Institute. 1983. The Fertilizer Handbook. The Fertilizer Institute, Washington, D.C.

Ohio State University Extension. Ohio Agronomy Guide. Bulletin 472.

Acknowledgments

The authors would like to thank the individuals listed here for reviewing the manuscript: Mark Sulc, OSU Extension Forage Specialist; Hank Bartholomew, Southern Ohio Grazing Coordinator; Ed Vollborn, Leader, Grazing; Jay Johnson, OSU Extension Fertility Specialist; Joy Ann Fischer, Communications and Technology; and Dave Miller, East District Farm Management Specialist. Also, thank you to Carla Wickham, Office Assistant, OSU Extension, Noble County.


Fertilizer Needs Worksheet

Step 1.

Determine fertilizer recommendations based on yield goals and soil test values.

Crop to be grown ______________________________________________

Yield goal ____________________________________________________

Fertilizer recommendations based on soil test.

pH _______________

N ________________ lb./A

P205 ______________ lb./A

K20 _______________ lb./A

It may be necessary to convert Phosphate P205 to elemental P or K20 to elemental K. Work in the same terms as the soil-test results.

P205 x 0.44 = Elemental P

K20 x 0.83 = Elemental K

Step 2.

Select a fertilizer blend or nutrient source.

________ lbs. of fertilizer to spread =

____________lb. of nutrient recommended by soil test

  ____________percentage of nutrient in source
(decimal form)

Example: 0-46-0 source we are comparing

_____________________ =
(lb. of fertilizer to spread)

__25 lb. P205 recommended by our soil test__
0.46 (percentage of P205 in our selected blend)

   
  pounds to apply per acre = 54.3 lb./A

Do the same steps for nitrogen and potash. These steps will tell you how much fertilizer you need.

If you are looking at purchasing nitrogen for a new planting, you need to consider residual nitrogen from the previous crop and past application of manures. Look at Table 2 and deduct the nitrogen credits from the nitrogen recommended on the soil test.

Step 3.

Calculate the tons of fertilizer needed.

___2,000 lb. per ton_____ = # of acres a ton will cover
lb./A to spread from Step 2

Example: From Step 2:

_2,000 lb. per ton_ = 36.8 acres we can cover
54.3 lb./A to apply

If we needed to fertilize 10 acres:

10 acres x 54.3 lb./A = 543 lb. of fertilizer needed.

_____________
(acres to spread)
x ___________________
(lb. of fertilizer per acre)
= Total lb. of fertilizer needed

Do this for each major nutrient needed.


Step 4.

Calculate cost per acre.

_______________
(fertilizer cost/ton)
÷ ________________
(# of acres you can
= fertilizer cost per acre
    spread per ton of
fertilizer, Step 3)
   


Example: 0-46-0 @ $249.90/ton ÷ 36.8 acres per ton  
  $249.90 ÷ 36.8 = $6.79 per acre cost of fertilizer

Step 5.

Calculate the spreading cost per acre.

________________
(Spreading cost/ton)
÷ ___________________________
(# of acres you can spread per ton)
= spreading cost per acre

Example: Spreading cost $6.00/ton

$ 6.00 ÷ 36.8 acres per ton = $0.16 spreading cost per acre


Step 6.

Calculate the total cost of fertilizer per acre.

___________________
(Fertilizer cost per acre)
+ ____________________
(Spreading cost per acre)
= ________________
(Total cost per acre)
Step 4
Step 4

 

*Spreading cost can be significant.


All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.

TDD No. 800-589-8292 (Ohio only) or 614-292-6181



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