Module 2:  Testing for fertilizer run-off.  Back to the top.

     Introduction:  This experiment is to find out if detectable amounts of nutrients will run-off from various types of soil.  This experiment would be best performed by giving each group a different type of soil to test.  This way the effect soil type has on run-off could be understood.  Hach nitrate and ammonia test kits will also be necessary.  These kits include simple, easy to follow instructions.  Also, the experiment could be performed using the manufacturers recommended amount of fertilizer (milorganite or ammonium nitrate) to see if there is still run-off when following packaging instructions. Click here to access the Data Table for one fertilizer type, or here for comparing chemical to organic fertilizer.

Materials:  For a class of 30, groups of three.  Please adjust according to class size.

1.   20 Plastic planter containers, large cups, or similar container with holes in

      the bottom for drainage.

2. Soil.  Examples include sand, peat moss, topsoil, clay, potting soil,        

      compost, or mixtures of the above.

3. Water.

            4.   Containers to hold the water.

4. Ammonium nitrate and or milorganite fertilizer.

2.      Hach Nitrate and/ or Ammonia kit.

3.      5ml to 10ml pipettes.  Small 10ml graduated cylinders will do if no

            pipettes are available.

Questions to ask, discuss, and record before beginning experiment:

1. What will the Hach kits be used to detect or test for? 
2. Using the directions that come with the kit review how the kits will be used before doing the experiment.
3. What are the properties of the soil to be tested?
4. Develop a hypothesis regarding whether soil type will effect fertilizer run-off. 
5. If using the milorganite and ammonium nitrate fertilizer:  Predict whether the organic or chemical fertilizer will produce the highest amount of run-off.

Procedure: 

1. Obtain two identical containers of soil.  Label one as control and the other as test.  Each group should use a different type of soil.
2. Pour an amount of fertilizer on top of the soil in the test container equal to double the recommended application amount given in the application instructions that come with the fertilizer.
3. Slowly pour water into both the control and test containers until water begins to flow from the bottom of both. 
4. Take a water sample from the drainage of the control and the test.  Label and put aside.
5. After water stops draining from the bottom of the containers slowly add more water until water again drains from the bottom of the containers.
6. Take a water sample from the bottom of each container.
7. After water stops draining from the bottom of both containers, again add water until water starts to flow through the bottom drains again.
8. Take a final (third) water sample. 
9. Test all three sets of samples using the Hach kits for the presence of nitrates or ammonia.

Questions to ask, discuss, and record after experiment:

1.     Discuss what was learned from the experiment.  Did everyone have the same

        results/ observations?  How did you hypothesis compare with the actually result?

2.     What were the characteristics of the soil type that allowed the most nitrate or

        ammonia to leech through?

3.     Prepare a bar graph comparing the type of soil with the amount of nitrate or

        ammonia run-off.

6.   Discuss some ways the experiment could be carried out differently.  For

       example, how could adding water more quickly or slowly affect the results?

       How would mixing various soils, such as sand and peat, affect the run-off of

       each?  How  would changing the experimental parameters affect the results?  For

       example, what if milorganite (organic fertilizer) were compared to ammonium

       nitrate fertilizer (chemical fertilizer)?  Would there be more run-off from

       milorganite or ammonium nitrate?  Try adding the fertilizers to water instead of   

       soil to compare the amount of nitrogen released by chemical fertilizers as

       compared to organic fertilizers.  Then perform the Hach test on the water. 

Data Table for Module 2:  For use with one fertilizer type. 

Data Table for Module 2:  For use with two fertilizer types.