Procedure

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Materials Needed:

  • 1 pair of gloves
  • 1 pair of goggles
  • 1 soil extractor
  • 1 hammer
  • 1 permanent marker
  • 24 labeled plastic bags
  • 1 soil chemical test kit
  • 72 nutrient agar plates for fungi
  • 72 15 mL transformation tubes
  • 1 beaker
  • Rubbing alcohol
  • Distilled water
  • 1 test tube rack
  • Field notebook
  • Pen/pencil
  • 24 pipettes
  • Sterile water

 

Step by Step Instructions to Recreate our Experiment:

1. Find 2 plots of land that are 10m x 10m with minimal plant life. One plot should contain more dead plant material than the other.

  

2. Pick one of the four corners of one plot and label 3 plastic bags with the name of the plot, the name of the corner, and the letter of the sample (e.g. one bag could be labeled "Site 1, Day 1, Northwest Corner, Sample A")

3. Repeat step 2 with the second plot.

  

4. Using a soil cylinder, take three soil samples that are 2.5cm in diameter and 15cm deep from the chosen corner in each site and place each in the corresponding plastic bag. To avoid contamination between samples, bring clean water to rinse the soil cylinder between each sample. Repeat steps 2-4 daily for 4 days. Take samples at the same time each day.

 

5. Perform serial dilutions for each sample. Using a new pipette, add 10 mL of sterile water to a 15 mL transformation tube labeled with 100 and the sample. Repeat this step, adding only 9 mL to an additional tube labeled with 10-1. Finally, add 9 mL to another tube labeled with 10-2.   

 



 
  

    6. Place 1 cc of the soil sample into the tube labaled 100 and shake vigorously.

  

 

 

7. Using a clean transfer pipette, remove 1 mL of the soil and water mixture and place into the tube labeled 10-1. Shake vigorously.

 

 


8. Remove 1 mL of the mixture from the 10-1 tube and place in the 10-2  tube. Shake vigorously.




9. Take 100 μl from each transformation tube and plate on the labeled corresponding nutrient agar plates. Allow to grow for 72 hours. Repeat for all samples. Dilutions should be done at the same time each day. After 72 hours, count plates for yeast and mold. Yeast should appear as small dots, and mold should appear larger and may be fuzzy. Use rubbing alcohol to clean table surface when finished.





10. Perform a soil extraction test for each sample using a soil test kit. Repeat daily for 4 days. Tests should be done at the same time each day

                                  
 

11. Perform a sulfate chemical test for each sample using a soil test kit. Repeat daily for 4 days. Tests should be done at the same time each day.

12. Perform a humus test for each sample using a soil test kit. Repeat daily for 4 days. Tests should be done at the same time each day.

 

   13. Analyze data and draw conclusions.