Figure 1
Average pH
Figure 1: Average pH
Figure 1 depicts the pH of the soil for the two conditions of the rain gardens, new and old. A pH probe was used to gather the pH measurement for the two conditions. Figure 1 depicts the average and standard deviations calculated from the class data resulting from this method for both soil type conditions. An unpaired t-test assuming unequal variance was conducted for this data, resulting in a p-value of 0.42 which is greater than the critical value of 0.05. The critical values gives us a percent chance of seeing these results given the null hypothesis to be true.
Method
To test the pH of the soils, we concocted a mixture of 3 grams of soil and 12 mL of DI water. The DI water was used to dilute the solution. The mixture was then placed in a vortex for 1 minute to thoroughly mix the soil with DI water. We then incubated the sample for 30 min at room temp swirling every 5 min. Once stabilized, we used a pH probe to read the pH of the solution.
Evidence
As seen from this bar graph, there is a higher pH value in the new rain garden than the old one. There is an 8.18 average in the new rain garden and 7.9 in the old one, showing that the pH in the new rain garden is about 0.28 greater. This shows that the pH in the new rain garden is 3.48% greater. We also collected data on the standard deviation which is to provide information on the variance between our data. The standard deviation for the new rain garden was 0.25 and for the old was 0.45. This helped us see that there was less variance between the pH in the new rain garden than the old. To provide a visualization of the standard deviation we use error bars which go along with showing that there is less variance of pH in the new rain garden than the old. To see if there were any significant differences between the pH in the old and new rain garden, we utilized a t-test. The t-test gave us a p-value of 0.42, and any value that is greater than or equal to 0.05 means they are not significantly different.
Conclusion
From the data in the graph, we performed a statistical test to test for differences between the samples. This test was a T-test, and it gave us our p-value, which was 0.42. Since our p-value is above 0.05, this means that the pH values of the old and new rain gardens are not significantly different. This means that these 2 data’s do not unique values. From this value, we are confident in our data and can certainly conclude that the age of rain gardens does not make a big difference in their pH values.
Explanation
pH can be referred to as the Hydrogen ion (H+) activity in a solution at equilibrium. Rainfall may change the pH of soil, but both rain gardens are subject to the same weather conditions in terms of season-to-season fluctuation. “Alterations of the rainfall patterns on a large scale occurring as a consequence of climate change and variability will have an effect on soil pH” (Rengel, Zdenko). Weather has a time scale influence that is much larger than the seasonal changes. The difference between the ages of the rain gardens we are testing is about 12 years, which is not significant enough to be considered a time scale in which larger scale weather patterns influence the pH of the soils. This explains why the pH of the soils of each rain garden is not significantly different. Topography, in large, can also have an influencing factor on pH. Topography is the study of land features and surfaces. Because our rain gardens are only 0.2 miles apart, the land in which they are grounded is not distinct enough for topography to be considered as a factor.