ALCA Members PLC Domains Data Standards Map Plan Curriculum Assessment Strategies

This Dirt Really Rocks! Copy

This activity will allow the student to take soil samples and test the sample for its pH. This activity can be as simple as using blue and red litmus paper to test only pH or it can be made more complex by using pHydrion paper, or even N-P-K test kits.

Engaging Questions

  • Do any other students have soil samples that LOOK the same as yours (i.e. color, texture)?  If so, what is their sample's pH?

  • Is your soil sample acidic or basic?

Teacher Goals

  • Soil Testing - Many students have heard about soil testing but may not have a good idea just what it is. This activity will allow the students to bring in soil samples and test the pH of their sample.

Required Resources

  • Indicator Paper

    • Litmus or pHydrion papers can be purchased from science supply houses very cheaply.

  • Soil Test Kit

    • Inexpensive soil test kits may be purchased in a variety of locations to expand this activity.

Optional Resources

  • Inexpensive soil test kits may be purchased in a variety of locations to expand this activity.

Steps

  1. Background

    1. Vinegar Test
    • Pour some vinegar into one of the small containers supplied by your teacher.  
    • Test it with the indicator paper.  
    • Determine the vinegar's pH. (Vinegar is a weak acid and should register as such with your indicator paper.)
    1. Baking Soda Test
    • Dissolve one gram of baking soda in some water.
    • Test it with your indicator paper.  Is this solution an acid or a base?

  2. Soil Collection

    1. Identify a location you want to collect your soil sample and write a brief description of the area around it (e.g., pasture with cattle, under a pin tree, garden).
    2. Gather some soil from your yard, garden, or farmland.  Place about fifty grams into a plastic baggie and seal so it won't spill.  The soil should be collected about 10 centimeters below the surface. 

  3. Design Step

    1. Design the different methods to determine the pH of your soil sample using pH paper.  
    2. Identify one method that would serve as a control.
    3. Use each method to determine pH.
    4. Compare results using different methods.
    5. Make recommendations on best method to determine soil pH.  (NOTE: If teacher has a soil pH meter, it will make this step much easier to draw conclusions.)

Teacher Notes

  • Soil pH can easily be detected by making a solution of soil and distilled water (use distilled water to avoid chemicals found in tapwater skewing your results).  Shake the sample and allow the soil to settle.  The liquid can then be tested using some type of indicator paper.  Use of pHydrion paper will allow a better quantitative result than plain litmus.After students have determined their sample's pH, they can compare locations, soil texture, soil appearance, etc. to see if there is some correlation.

Please enter a Registration Key to continue.