- -   AGRICULTURE CORE CURRICULUM  - -


(CLF7000)  Advanced Core Cluster:  PLANT AND SOIL SCIENCE

  (CLF7450)   Unit Title:  ELEMENTS NECESSARY FOR PLANT GROWTH

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  (CLF7454)   Topic:  READING THE             Time         Taught in Year(s) 
                      FERTILIZER LABEL       1 Hour            3 and 4  
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         Topic Objectives:  Upon completion of this lesson the student will 
         be able to:

         Learning Outcome #:

           (H-4)  -  Read the directions on a fertilizer label and 
                     demonstrate proper dilution and application techniques.

           (H-5)  -  Calculate the content of N-P-K in a fertilizer 
                     container from information on the package.

           (H-15) -  Calculate the amount of fertilizer needed for an acre 
                     of crop using a selected nitrogen source.

           (H-4,  -  Calculate the cost per pound of plant nutrient in ton
            5, 15)   of fertilizer.

         Special Materials and Equipment: Sample fertilizer labels.

         References: Interstate Printers and Publishers, Inc.
                     WESTERN FERTILIZER HANDBOOK.
                     pages 83 to 84.

                     Hartman.  PLANT SCIENCE.
                     Pages 205 and 206.

         Evaluation: Quiz by instructor

TOPIC PRESENTATION:  READING THE FERTILIZER LABEL

A.  A fertilizer may contain one or more of the three primary nutrients:
    nitrogen, phosphorus and potassium.

    1.  A container of fertilizer may also contain some secondary or 
        micronutrients.

    2.  A little observation and study will help you understand the meaning 
        of information shown on a fertilizer container (label).

B.  Each bag of commercial fertilizer carries a label stating the analysis 
    of its contents.

    1.  This analysis is represented by three figures:  for examples, 
        21-7-14.  This three number designation is called a "grade".

         a.  The first figure is the percent nitrogen by weight, in this 
             case 21 pounds per 100 pounds of fertilizer.

         b.  The second figure is phosphorus, specifically 7 percent 
             phosphoric acid (P2O5).

         c.  The third figure represents potassium, specifically the 14 
             percent potassium (K2O).

    2.  Another way of viewing the above information is that a ton of 
        21-7-14 fertilizer contains:

        a.  420 pounds of nitrogen.

        b.  140 pounds of phosphorus (P2O5).

        c.  280 pounds of potassium (K2O).

        d.  the total of all nutrients is 840 pounds.

        e.  The remaining 1160 pounds consists of other elements in the 
            formulation.  These include oxygen, sulfur, magnesium, calcium 
            and others. NH4NO3 or ammonium nitrate is o