Part of what I will be doing for this study is a small research study on how pH levels in soil change as the temperature gets gradually cooler in this fall season. This document outlines how I will carry out the experiment in a way that is organized and easy to understand. It will be updated near the end of November once all of my data is collected and analyzed.
Field Study
Experimental Design Diagram
A. Stated Question: How does the acidity of soil change as the temperature ultimately decreases?
B. Hypothesis: If the temperature continues to decrease, then the soil will become less acidic and more basic/alkaline because the ground will gradually begin to harden, causing the soil to lose much of its moisture, which can definitely include acidic material.
C. Data Tables
The Acidity of the Soil Depends on the Decrease in Temperature |
Date | pH of Soil |
Average |
Trial 1 | Trial 2 | Trial 3 |
9/11/11
| 7.0
| 7.0
| 7.0
| 7.0
|
9/28/11
| 7.0
| 7.0
| 7.0
| 7.0
|
10/9/11
| 7.0
| 7.0
| 7.0
| 7.0
|
10/30/11
| 7.5
| 7.5
| 7.5
| 7.5
|
11/20/11
| 7.5
| 7.5
| 7.5
| 7.5
|
11/27/11
| 8.0
| 8.0
| 7.0
| 7.67
|
Date | Temperature Recorded |
9/11/11
| 79º F
|
9/28/11
| 58º F
|
10/9/11
| 77º F
|
10/30/11
| 54º F
|
11/20/11
| 43º F
|
11/27/11
| 38º F
|
D. Controlled Variables:
1. The same general area of ground (to the nearest foot) will be used to test the pH levels.
2. The same method of testing the pH will be used each time, using a soil kit.
3. The same type of soil will be used in each test from the same area (the same consistency of the sand and dirt mixture).
4. After each collection at the field study location, every soil sample will be secured in a zipped plastic bag in order to prevent moisture from escaping.
5. No new soil samples will be taken within a week of the previous tests to ensure accurate results. This will follow the same guidelines of when I will be taking observations at my field.
E. Materials Required:
Plastic zippered bag
Small shovel (if desired; you can use your hands)
Soil Test Kit (to test the pH levels)
F. Step-By-Step Procedure:
Upon each visit to the field, take a small sample of soil from the same area, using a small hand shovel to dig 2-3 cm into the earth past the topsoil.** Fill in a plastic zippered bag.
Once the sample has been collected, use the Soil Test Kit, carefully following the directions listed to test the pH levels in the soil you have collected. (Place the soil in the testing bays and squeeze a couple of drops of the indicator on each sample. Tilt the testing tray downward to let the indicator run down. You should be able to see the color that the indicator has changed. Then, use the key included in the testing kit to determine the pH level). Be sure to do three trials with each sample.
When the results have been received after testing, record them in the table, along with the average of the three trials.
In the next table, record the date and the air temperature at the time of collection.
Follow the above instructions each time you take a new sample of soil. Once the sixth sample has been collected, conclusions will be able to be drawn from the data.
**This step was not followed completely with the first sample collection and may alter data slightly. I will this in mind for data analysis.
G. Graphs of Data
H. Conclusion
a. Does the data support the hypothesis?
Yes, my data supports my hypothesis very well. The acidity decreased over time, just as I had predicted would happen. Looking back on my data, the warmer the temperature was, the higher the acidity was in the soil. The season began quite warm, with a 70º+ visit to start. This visit contained a soil testing that came back with a pH of exactly 7.0, or neutral. Soil acidity was also neutral during the second visit, when the temperature was 58º in the evening. October's visits proved to be very mild in terms of temperature, and the pH levels stayed neutral, which wasn't very surprising to me in my hypothesis. I expected the pH to change once the temperature ultimately changed, and it did not change until my last October visit, which was on October 30. Here, the temperature was 54º F, and the pH level was 7.5, a shift more toward being basic than neutral. Tests came back for the first November visit at a pH of 7.5 as well. At this visit, the temperature had decreased to just 43º F. And on the last visit, at a temperature of 38º F, the pH was determined to be 8.0, even more alkaline than my previous tests, which were at 7.5. All of these numbers mostly supported my hypothesis. I was, however, surprised at first to see that the pH levels stayed at 7.0 for so long; however, once I looked back, I realized that the mild temperatures may have contributed to this. I had expected more variation in temperature earlier in the season, but this fall was quite unusual in terms of its being very unseasonably warmer. I also expected to see some numbers higher than 8.0, maybe closer to 9.0 for pH. Given the weather we experienced, I don't think that the ground had enough time to harden even more than it did, which is why it gave me some different numbers. All in all, the data that I did receive reflected my hypothesis quite well.
b. If you did the experiment again, what changes would you make and why?
First of all, as noted in my explanation above, I would have collected my first sample the same way I collected the rest of the samples. It doesn't appear that it made a huge difference because the numbers stayed at 7.0 for quite a while, yet to be scientifically precise, I should have had a better plan going into it. Another change I would love to make to this experiment if I repeated it would be the addition of snow. In my hypothesis, I mentioned that the ground would eventually get harder, causing the soil to lose some of its moisture. Because I knew this to be true already, I knew that having snow on the ground for a long period of time could possibly have a great influence on my pH levels. Yet, in the crazy weather we experience in this great state, I unfortunately did not have snow on the ground during any of my visits. One last change I would make if I repeated this experiment would be in how I collected the soil samples. For this experiment, my samples were taken very close to the surface. However, I am somewhat convinced that my results could have been different had I dug down a few inches into the soil. Deeper soil would have had more moisture, which could have given me some different results in my pH testing.
