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So last weekend, my family bought something pretty cool.
Something we’re sure you’ve always wanted.
No, it’s not a pony.
It’s a rotating compost bin!
Yeah!
It’s for compost and it rotates.
Which is going to be so awesome because the rotating part, that allows it to get aeration.
You may already know about compost.
It’s where biodegradable things can decompose and the whole idea is---after decomposing,
the result is this nutrient rich organic material that you can provide your plants with.
So I’m thinking after a while of adding leaves, banana peels, grass clippings, twigs,
overripe fruit…ok I could keep going but I won’t…after all these items break down
and decompose, I’m hoping to get some nutrient rich material for my plants.
So why am I even talking about this?
Well there are two major things that compost supplies plants with that are so important---carbon
and nitrogen.
We’re going to spend some type talking about these 2 elements---and their cycles---because
both are so important for life.
With so many incredible elements on the Periodic table, we don’t know if it’s really fair
to have a favorite.
But we do.
It’s carbon.
Sorry nitrogen, you’re cool too.
But why the love for carbon?
Well, we really love how versatile it is.
In one form it could make up your pencil led---which isn’t really lead at all, it’s graphite.
It’s a form of carbon.
In another form, carbon can make up one of the hardest substances, diamond.
The big 4 biomolecules---carbohydrates, lipids, proteins, and nucleic acids—they all have
carbon.
In fact, molecules that contain carbon are known to be organic molecules.
Organic chemistry is a branch of science that studies the interactions of molecules that
contain carbon!
Just look at this carbon atom.
Ahh, just look at it.
It has 4 valence electrons.
Carbon has the ability to form tons of compounds.
Carbon is often known as a building block in life for this reason.
Now that we understand how important carbon is, let’s make sure we understand how we
get carbon.
That means we need to take a look at how carbon can cycle.
First it’s important to understand that there are carbon reservoirs and that the carbon
cycle is really an exchange of carbon among these reservoirs.
Reservoirs being where carbon is basically hanging out.
So here are some major examples of where carbon is found: Carbon is dissolved in the ocean.
It is in rocks and fossil fuels.
It is in living organisms.
It can be in the atmosphere.
So the idea is to understand that carbon cycles among these reservoirs.
Now our time is limited…let’s take a look at one pathway.
Consider carbon dioxide in the atmosphere.
It is taken in by organisms that perform photosynthesis.
This may be plants, like land plants.
It may be algae in oceans or lakes.
The carbon becomes a part of that photosynthetic organism.
If the photosynthetic organism is eaten by an animal, it becomes a part of that animal
too.
And the animals that eat that animal.
Both the plants and animals do cellular respiration which releases carbon dioxide.
When the plants and animals die, the carbon from their bodies can be stored in sediment
over a long period of time---after a very long time, they can even be converted into
a fossil fuels.
The burning of fossil fuels produces a lot of carbon dioxide---and this has also led
to the concern of excessive carbon dioxide in the atmosphere.
Carbon dioxide is a ‘greenhouse gas’ which means that it can trap heat in the atmosphere-------so
too much carbon dioxide----is not a good thing.
So what about nitrogen?
Nitrogen is a critical element in amino acids, which are the monomers of proteins----and
an element of nucleotides, which are the monomers of nucleic acids.
And if you remember from our biomolecule video, proteins and nucleic acids are two very important
biomolecules for life.
Nitrogen is kind of a big deal in the atmosphere considering it’s the primary gas in the
atmosphere.
The thing about nitrogen is that it is much more useful to organisms when fixed into other,
more usable forms.
Nitrogen can be fixed by bacteria which could be living in the soil or even in the roots
of some types of plants where the bacteria live in symbiotic harmony inside the roots---meaning
the bacteria get a home in the plant root and the plants get the benefit of fixed nitrogen.
Once again, we’re just looking at one pathway here in the nitrogen cycle so keep in mind
this is just one way for nitrogen to cycle.
Ok so let’s take a look at this nitrogen in the atmosphere.
Consider the types of plants that have nitrogen fixing bacteria living in their roots---the
nitrogen is fixed by those bacteria into a form of nitrogen known as ammonia and ammonium.
Nitrifying bacteria in the soil can convert the ammonium to nitrates and nitrites, forms
of nitrogen that plants can also easily use and assimilate.
Then animals can eat those plants and obtain nitrogen.
When both plants and animals decompose, decomposers return ammonia to the soil in a process called
ammonification where it could be reused again.
But not all of the nitrates and nitrites get assimilated by plants, eaten by animals, and
then converted back into ammonia.
There are also another type of bacteria in the soil…drumroll….denitrifying bacteria!
Denitrifying bacteria in the soil can convert nitrates and nitrites back into atmospheric
nitrogen gas.
Again this is one example of nitrogen cycling through, but keep in mind that this happens
in both aquatic and terrestrial environments and there are other ways for nitrogen to be
fixed and cycle.
You know how we mentioned that too much carbon dioxide can be problematic?
You want a balance in these cycles.
There’s a balance for the nitrogen cycle too and nitrogen pollution can be problematic.
Consider plant fertilizer.
Plants love it.
It contains a form of nitrogen.
Well, if it’s not used responsibly, the excess nitrogen in fertilizing crops can drain
into bodies of water.
One reason this could be harmful is that it will basically cause an aquatic producer heyday!
All of the algae and water plants now have this crazy load of nitrogen for growth.
That might sound like a good thing but all this producer excessive growth is messy---it
can block light to the water and when they die and decompose, all that decomposing uses
up a lot of dissolved oxygen in the water which can be harmful to aquatic life.
Phew!
You know, this recycling of carbon and nitrogen is pretty remarkable.
Just think---you could contain a carbon atom that was once part of…a dinosaur!
Because of all this recycling.
The carbon and nitrogen cycle---just another beautiful thing connecting all of us.
Well I better get back to my compost.
That’s it for the amoeba sisters and we remind you to stay curious!