hmm…you’ll find out. Mr. Brock I have a question. What are we doing today? What’s ecology? Ecology, right?
Ecology, in my notes on the reading, the definition of ecology is the study of organisms and the relationship with their environment.
Actually soil is very important. You would be amazed at all the significant things it does and what lives in it, like millions of tiny microbes. Ohhhh…lots of things!!! Oh no, I know exactly what’s coming. Let me grab my jacket, we are about to get messy. How can dirt be important…
Exactly where Caroline said, some place messy. Uh-hu! Everyone knows what to do, come on get on the surfboard. Let me guess, in the dirt, with all the worms, and cicadas. Why would we need a coat? I have a question, where are we going?
Well, according to my calculations, using my GPS navigator, we arrreee on the fields.
Ew! What is that!? Oh my! A snake! No…that would be a worm. don’t you mean…in the fields
Ahh! You’ve all turned into great big, ugly, green blobs! Calm down, we’re just bacteria In case you haven’t noticed, you’re one too Now look around you, what do you see?
There’s more of them! And they’re all coming towards us! Why oh why did I come to school today… Calm down and observe the bacteria’s behavior, you would see that they are currently letting out secretions into the soil. Well why would they do that?
I already know which one will work the best, and it has to be the playground wall! Erosion? Uh, oh what’s erosion? That doesn’t sound too good… Well, we would need to construct an experiment to test for the soil structure and the number of bacteria at the different sites. As a base negative control, we will need to also have an area where the land is flat, and at the highest point on campus. To test for how well the erosion prevention methods work, we will also need to test the soil above and below the erosion prevention methods, to compare the difference in bacteria levels. Wow! I saw that on the discovery channel! There are 3 different components in soil: sand, silt, and clay. The perfect type of soil for preventing erosion would have an equal distribution of each component. The clay helps to trap the sand from eroding, and the silt helps to trap all of it. Well in my dictionary it states that the definition of erosion is the “washing away of soil.” Don’t you see the soil? It’s starting to stick together! Well maybe, but we’ll have to do the experiment to know for sure. How would do we figure out which method works the best? Wow, so do the fields stop a lot of erosion? Are there other places at RPCS that prevent erosion? I never see any! Actually, Megan there are other methods that you might not have noticed. Such as, the wall located at the lower school playground, and the woodchips lain down on the trail leading to the backwoods. Good observation Stephanie, the bacteria is letting out secretions which help the soil to stick together, which creates good soil structure, and is useful in preventing erosion. Well it’s hard to tell, in order to really find out, you would also have to test how well the field’s natural erosion prevention method, grass, prevents erosion as well. well its time to test out your hypothesis class, so hop onto my Magic Surfboard and let’s find out.
Oh and by the way, don’t forget that you need to run your tests for two trials, and will need to collect 3 samples of soil at each site. You just need to record the soil structure and test for the bacteria density at each site. Then report back to the lab and we’ll figure out what your results mean. I will leave you with my magic flying surfboard. Yes! We’re us again! Thank goodness! I just need to call my trusty Mexican penguin, Pepito! But how will you get back to class Mr. Brock? Mr. Brock, how are we going to do this?
Ok, lets get started then. Megan, you and I will figure out the soil structure at each site. Stephanie and Meghan, you will cover the bacteria density. It’s mostly silt, that’s why. According to my soil test, there is 68% silt, 28% sand, and 4% clay. Well after taking the average for both trials there are about 11.3 million bacteria per cc. Lets go to some other sites now. Wow! This soil is spongy! Sounds good! So Stephanie, how high is the bacteria level here? Ok!
Hmm…there seems to be a big difference between the number of bacteria at the top of the fields compared to the bottom. Since the bacteria density decreased so much from the top of the field to the bottom, erosion must still be occurring here, and the grass must not be working to prevent soil from eroding. This soil looks a little bit like the soil at the plot near the parking lot. So is this soil good or bad? Ok, then lets head to the playground I need a break! Jump on Well the high field has 47% silt, 33% sand, and 20% clay. The bottom is composed of 50% silt, 35% sand, and 15% clay. Overall I would say that this soil is pretty healthy, the soil is better at the top then the bottom, so erosion could be taking place in-between and causing poorer soil structure. Well, according to my bacteria calculations using my apgar film, there are about 30.5 million bacteria colonies per cc at the top of the fields, and about 18.6 million bacteria colonies per cc at the bottom of the fields. You’re right it is similar, at the top and bottom of the fields the soil is mostly silt, and has similar amounts of sand and clay as the high plot.
Oh this time the bacteria density increased from the high area to the low area! That means that the erosion prevention method, the wall, is working to prevent soil erosion! I don’t see nearly as much bacteria as the other sites. Yes that’s right, now we need to check out our last site, the trail. You are right, there are only about 7.3 million colonies per cc at the high playground. At the low playground there are only about 8.5 million colonies per cc. That’s because this soil has no silt, it is 61% sand and 39% clay. Hmm…overall I would say that the playground has very poor soil, and it could very easily be eroded. There is not an equal distribution of clay, sand and silt. This is strange, at the top of the playground most of it isn’t even soil, its detritus! Detritus is the beginnings of soil. The 23% of it that is soil is silt. Oww! What did I just land on! Eww…the soil at the bottom of the playground is sticking to my shoe! I think that would be a woodchip.
Ahh! Yeah I definitely just got sand in my eyes! Ahh, get it out! Well that would make sense because both the high and low trails have a high amount of sand. The high trail is composed of 48% sand, 35% silt, and 17% clay: which is pretty good. The low trail has 65% sand, 25% silt, and 10% clay: which is not as good as the top of the trail, but is still not terrible. This is good! There is a lot more bacteria at the bottom of the trail then the top of the trail!
To the surfboard! Yes! You’re right! At the top of the trail there are about 9 million bacteria colonies per cc. At the bottom there are about 18.7 million bacteria colonies per cc! That’s a huge increase from top to bottom, so now that we have our data, can we go back to the lab?
But it’s not like we found out anything… Yes! We’re back at last!
Really? Mr. Brock, I’m still confused. Which one prevented the most erosion?
We can combine all of our graphs on bacteria density that we produced at each site to compare which areas had an increase in bacteria density from above the site to below it. Once we have done that, we simply look for the greatest increase. We have to look at the soil structure to tell which soil had the best structure before and after erosion. Lets review our findings.
Here are our bar graphs that show the results. According to our graphs the trail had the largest increase in bacteria from the top to the bottom.
The fields had the best soil structure, but the grass used was the worst method to prevent erosion. The retaining wall built by the playground would have been the best erosion method, but the soil was the least healthy. In the backwoods, the soil was healthy and the method of using woodchips was effective in maintaining the healthy soil with bacteria. So our hypothesis was wrong, the retaining wall at the playground was not the best area equipped for preventing erosion, the trail was because of its woodchips and good soil structure. That was awesome! What are we doing next class Mr. Brock? Wow! There is something up there! What about soil structure?