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The Effects of Soil Type on Bean Germination Mr. Spotts 18 December, 2007 6A C.O.R.E. ABSTRACT This experiment was designed to test the idea that bean seeds might sprout better depending on the type of soil in which they were planted. I hypothesized that the beans would sprout faster in Soil A, which is browner and contains more organic matter. The independent variable in the experiment was soil type, and the dependent variable was the growth of the beans. Variables that were controlled include the amount of light and water the beans received, the type of seeds and the method in which they were planted. Each student in class prepared their planting cup by punching five holes in the bottom and placing a 2 inch by 2 inch piece of paper towel in the inside. One of two types of soil was filled to the blue line, and five pinto bean seeds were place on that. Seeds were covered by 0.25 additional inches of soil and then placed water-filled trays contained in the classroom growth chamber. Results of how many seeds sprouted in each cup and for each treatment as a whole were recorded in the data table at the beginning of class for four class periods. Classroom data was compiled and graphed using Microsoft Excel. The data showed that while a greater number of seeds planted in Soil A sprouted, the percentage of seeds that sprouted in each soil type were very similar. Problems that were encountered included 1) mold growing on the top of the cups that might have prevented additional seeds from sprouting; and 2) some students not planting seeds according to directions. Analysis of the limited data we had led me to the conclusion that the bean seeds did not sprout faster in Soil A compared to Soil B, meaning that my hypothesis was proven wrong. QUESTION The question we attempted to answer by conducting this experiment was “Does the soil type in which bean seeds are planted determine how fast the beans will sprout?” HYPOTHESIS Based on what I knew about soils from the science unit “Solving the Garden Problem”, I thought that the bean seeds would sprout first in Soil A. VARIABLES The independent variable in this experiment was the type of soil used to plant the seeds. The dependent variable was the sprouting of the bean seeds. Variables that were controlled include the amount of light and water the beans received, the type of seeds and the method in which they were planted. INTRODUCTION The first unit covered in 6th grade science class dealt with properties of soil. We examined different soils and learned about soil composition, texture, organic matter and nutrients. Our textbook was set up so we could examine a school garden and identify potential problems as to why the garden wouldn’t grow plants. One possible explanation was that the soil was the wrong type to grown the plants. In the lessons, we learned that there are different types of soil in different areas of the country, and I know that certain crops can only be grown well in certain areas of the country. For example, corn and soybeans are grown in Illinois, while cotton is better grown in Mississippi. This got me to thinking about how soil type might affect whether or not plants would germinate or not. I decided to do this experiment in order to test if one type of soil would be better for growing pinto beans. MATERIALS The materials we included in our experiment included the following: Cup Soil A Water Paper Towel Soil B Growth chamber Pencil or pen Pinto bean seeds Data sheet METHODS Students followed a precise order of steps in order to test their hypotheses. First, each student in class prepared his/her planting cup by punching five holes in the bottom of the cup with a pencil or pen. Next, a 2 inch by 2 inch piece of paper towel was placed inside the cup to act as a wick to get water up into the soil. Then, students put one of two types of soil in their cup up to the pre-marked blue line and lightly packed the soil with their fingers. Five pinto bean seeds were place on the lightly packed soil, and the seeds were then covered by 0.25 additional inches of the same type of soil. After writing their names and soil types on the outside of their cups, students placed their seed cups in water-filled trays contained in the classroom growth chamber. Results of how many seeds sprouted in each cup and for each treatment as a whole (Soil A and Soil B) were recorded in the data table at the beginning of class for four class periods. RESULTS Data on the bean germination was collected four times after the initial planting. Results are shown in both table and graph form below. Class Bean Seed Germination Data Table Sampling Total Sprouts Total Sprouts Date in Soil A Cups in Soil B Cups 19 Nov 07 0 0 22 Nov 07 1 0 23 Nov 07 2 1 27 Nov 07 5 3 29 Nov 07 5 3 Soil Type Vs. Bean Seed Germination 6 Number of Bean Sprouts 5 4 Soil A 3 Soil B 2 1 0 19 Nov 22 Nov 23 Nov 27 Nov 29 Nov Observation Dates CONCLUSIONS The hypothesis in this experiment is that bean seeds will sprout more quickly in Soil Type A. After four series of classroom observations, the data showed that in fact a greater number of seeds planted in Soil A sprouted. On the surface, this would lend support to the hypothesis. However, the percentage of seeds that sprouted in Soil A and Soil B were both very low and ended up being similar. In Soil A, 5 out of 75 seeds germinated, which was only 6.7%. In Soil B, 3 out of 55 seeds germinated, which was only 5.4%. At such low levels of germination, it is impossible to state with confidence that the soil type had any affect on bean seed germination. Possible explanations for the low germination rate are centered on two problems. First, many students noticed a white filamentous mold growing both on bean seeds and on the top of both types of soil in the cups. This could be due to non-sterile conditions in the growth chamber or too much moisture in the general area of the growth chamber. Posters hung to shield the experiment from the other science classes may have acted like a barrier, preventing moisture from spreading out into the science room. Either the mold itself or the humid conditions that led to the mold growth may might have kept other seeds from sprouting. Secondly, some students did not plant their seeds exactly according to directions. This could have introduced other variables into the experiment that kept bean seeds from germinating. Final analysis of the limited data we had led me to the conclusion that the bean seeds did not sprout faster in Soil A compared to Soil B, meaning that my hypothesis was proven wrong. Based on these results, one possible extension of this research would be to conduct the experiment in a less humid environment. Less water could be kept in the trays, and a small fan could be used to blow humid air out of the growth chamber. Additionally, a student could conduct further research on the effects of mold and/or humidity on the germination of bean seed. ACKNOWLEDGEMENTS I would like to extend my appreciation to the sixth grade students at NKO Middles School, without whom this experiment could not have occurred. Secondly, I would like to thank Mr. Hudson who fixed the electrical outlet in the science lab, and Mr. Bly, who provided insight and feedback on the experimental design. Finally, I would like to thank Michael Anthony Booker, my former student at Greenville-Weston High School in Greenville, MS, who convinced me that in order for students to learn about science, they must be involved in doing science. BIBLIOGRAPHY 1. Science Buddies Topic Selection Wizard, Kenneth Lafferty Hess Family Charitable Foundation, http://www.sciencebuddies.org/mentoring/tsw_start.shtml 2. University of California at Berkely, Issues and Earth Science. Berkely: Lab Aids Inc., 2006.
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