Plants & Human Affairs (BIOL106)  -  Stephen G. Saupe, Ph.D.; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321; ssaupe@csbsju.edu; http://www.employees.csbsju.edu/ssaupe

Fertilizer Label Analysis

    Fertilizers must adhere to strict labeling guidelines set by the government.  On the fertilizer label provided locate the following:

1. brand name
    

2. the analysis, grade or formula � the three numbers are the percentage by weight of nitrogen, available phosphoric acid and soluble potash)
    

3. manufacturer�s guaranteed minimum analysis
    

4. amount of nitrogen claimed from all sources
    

5. sources of nitrogen
    

6. amount and source of phosphorus claimed
    

7. amount and source of soluble potash claimed
    

8. guaranteed percentages of other plant nutrients (not always listed even though they may be present)
    

9. acidity or alkalinity of the fertilizer (given in pounds of pure limestone, calcium carbonate, required to neutralize one ton of fertilizers)
    

This exercise is adapted from Hershey, D (1990) Sleuthing the nutrients that make your houseplants grow.  Science Activities 27: 17 � 20.

Last updated:  01/11/2005 / � Copyright  by SG Saupe / URL:http://www.employees.csbsju.edu/ssaupe/index.html