hmm…you’ll find

out.

Ecology,

right?

What’s ecology?

Mr. Brock I have a

question. What are we doing today?

Ecology, in my notes on the reading, the definition of ecology is the study of organisms and the

relationship with their environment.

Today we are talking about a specific type of ecology, soil ecology.

What’s so important about soil?

Ohhhh…lots of things!!!

How can dirt be

important…

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.

Oh no, I know exactly what’s

coming. Let me grab my jacket, we are

about to get messy.

Why would we need a coat? I have a question, where are we

going?

Exactly where Caroline said,

some place messy.

Let me guess, in the dirt, with all the worms,

and cicadas.

Uh-hu! Everyone knows what to do, come on get on the

surfboard.

1-2-3…IN THE SOIL!!!!!!!!!

Mr. Brock, where are

we?

Well, according to my calculations, using my

GPS navigator, we arrreee on the fields.

don’t you mean…in the fields

Ew! What is that!? Oh my! A snake!

No…that would be a worm.

Now look around you, what do you see?

Ahh! You’ve all turned into great big, ugly,

green blobs!

In case you haven’t noticed,

you’re one too

Calm down, we’re just bacteria

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?

Don’t you see the soil? It’s starting

to stick together!

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.

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.

Erosion? Uh, oh what’s erosion? That doesn’t

sound too good…

Well in my dictionary it states that the definition

of erosion is the “washing away of soil.”

Wow, so do the fields stop

a lot of 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.

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.

How would do we figure out which method

works the best?

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.

I already know which one will work the best, and it has to be

the playground wall!

Well maybe, but we’ll have to do the

experiment to know for sure.

well its time to test out your hypothesis class, so hop onto my Magic Surfboard and let’s

find out.

1-2-3 PARKING LOT!!!!!

Yes! We’re us again! Thank

goodness!

Mr. Brock, how are we going to do

this?

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.

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.

But how will you get back to class Mr.

Brock?

I just need to call my

trusty Mexican penguin, Pepito!

To the Bio Room!

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.

Ok!

Wow! This soil is

spongy!

It’s mostly silt, that’s why.

According to my soil test, there is 68% silt, 28% sand, and 4%

clay.

So Stephanie, how high is the bacteria

level here?

Well after taking the average for both trials there are about 11.3

million bacteria per cc. Lets go to some other sites

now.

Sounds good!

1-2-3 FIELDS!!!!!

This soil looks a little bit like the soil at the plot near the parking lot.

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.

So is this soil good or bad?

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.

Hmm…there seems to be a big

difference between the

number of bacteria at the top of the

fields compared to the bottom. 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.

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.

Ok, then lets head to the

playground I need a break!

Jump on

1-2-3 PLAYGROUND!!!!!!

Oww! What did I just land

on! I think that would be a woodchip.

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.

Eww…the soil at the bottom of the

playground is sticking to my

shoe!

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.

I don’t see nearly as much bacteria as

the other sites.

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.

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!

Yes that’s right, now we need to check out our last site, the trail.

1-2-3 TRAIL!!!!!!

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!

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?

To the surfboard

!

1-2-3 BIO ROOM!!!!!!

Yes! We’re back at last!

But it’s not like we found out anything…

Actually I think we could have found the

answer to our problem!

Really? Mr. Brock, I’m still confused. Which one

prevented the most erosion?

Lets review our findings.

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.

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.

What about soil structure?

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.

Wow! There is something

up there!

That was

awesome!

What are we doing next class Mr.

Brock?

I will be away inventing the time machine. You will

have a sub.

Uh-oh!