The Effect of Nutrients on the Propagation and Growth of Potamogeton Perfoliatus (Redhead Grass) (page 4)
Statistical Analysis: Did Nutrients Affect Growth?
t=1.66 for df=40
95% Confidence level, 2-tail, t = 2.02
Therefore, must accept Null Hypothesis
There is only a 90% Probability that means are from different populations, that Nitrates contributed to growth.
Problem 1: The Effect of Nutrients
After completing this phase of the experiment, I accept the Null hypothesis.
I was not able to achieve a 95% confidence level, a T value of 2.02; the confidence level achieved was 90%, a T value of 1.66. This is because the standard deviations were very high and the means were not far enough apart for the standard deviations to be insignificant.
Although the bar graph and box-whisker plot both show that the plants with nutrients did grow more the ranges of data show otherwise. The quartiles on the plot were very similar; one was not much lower or higher than the other. Also the standard deviations were high; both were in the thirties. Also this does not show how many zeros or dead plants there were in both sets.
Every week growth was measured in centimeters. In the first trial the planting was not done in accurate grids, thus making it very hard to keep track of plants from week to week. In the second trial, only the tallest shoot was recorded from each plant, this was flawed in that if a plant had six short shoots and another had one slightly longer shoot, there was no proof that the latter was longer, in fact the former would have grown more. In the third trial, if a plant had multiple shoots then all of the shoots were measured and recorded as such.
I thus conclude, from the data that adding nutrients to the sediment does not affect the growth of Potamogeton perfoliatus.
Problem 2: Effect on Water Quality
After completing this phase of the experiment, I accept my hypothesis stating that the addition of nutrients to soil only affects nutrient levels.
The nitrate level increased from 0ppm (parts per million) to 15ppm, in the tank with nutrients added. The tank with out additional nutrients stayed the same (0ppm). This statement held true for both pH (8.8) and salinity (1.0025) as well.
Two tanks were prepared with soil and water. The three tests were done. After two weeks all of the tests were run again.
I thus conclude, that only nitrate levels are affected by the addition of nutrients to the sediment.
Problem 3: Growth Patterns
After completing this phase of the experiment, I reject my hypothesis stating that the growth starts slowly, increases rapidly, and then slows down again. The growth increases very little, 2cm, between the first and second week. Although between weeks two and three the growth increases 10.9 cm. Nowhere in the data do the growth levels even out and climb steadily.
I thus conclude that Potamogeton perfoliatus grows very slowly then the growth increases.
This project was started with a possible future usage in mind. Mr. Lee Karrh introduced me to SAV and nutrients last June. He works for DNR- Department of Natural Resources- and works with the Bay Grasses in Classes program. Its purpose is to have students grow SAV in their classrooms then to transplant them into the Bay. Since the Wild Celery used in the program had always grown well without nutrients none were ever used. Mr. Karrh thought that adding Miracle Grow sticks to the sediment would increase the growth rate, and wanted a project to be done to test this hypothesis.
Therefore, there is the obvious application, use in laboratory grown plants and tests. But also Miracle Grow or a similar substance could be added to the soil of the Chesapeake Bay and its tributaries to increase the growth of beds. This should not happen anytime soon unless the benefits outweigh the disadvantages of adding even more nutrients to the bay.
If this experiment could be done over again, only small corrections would be made. First, this procedure would be followed for more than one trial; most likely three trials would be completed. Second, a more complete sample would be taken; this would include weighing the plants and taking photographs of the trays. Third, I should have made trials two months long each; this was not possible in the amount of time I had. I would also like to be able to count total nitrogen in the tanks because one of the tanks had a lot of algae in the water but the nitrate level was zero, this only means that all of the nitrogen was in the algae and none was in the water. Then in Problem 2 it would have been beneficial if the water quality level had been tested more than once.
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