Student Research Reports

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“Why don’t plants seem to grow under black walnut trees (Juglans nigra), but seem to grow under American elm trees (Ulmus americana)?” is the experimental question. This project was done because there were not so many plants growing under black walnut trees. This research is important because this could be a way to help walnut farmers better use the land under their walnut trees and be able to produce a second crop. The hypothesis is the soil under black walnut trees will have a lower pH (more acidic) than soil under American elm trees. This study was conducted by testing the pH of soil from one meter and two meters away from black walnut trees and American elm trees using the GLOBE Program protocol for soil pH testing. The results were very confusing because the difference in pH between black walnut trees and American elm trees was statistically insignificant, indicating the results did not support my hypothesis. Therefore, there must be another variable which accounts for the seemingly lack of plants growing under black walnut trees compared to American elm trees. Even though the data does not support the hypothesis, pH should be able to be eliminated as a potential factor in determining plant growth under these two plant species. As a consequence, other factors such as water use, toxins, or possible symbiotic relationships should be considered for further study.