The grass is always greener above the
septic tank.
Excuse me?
The grass is always greener above the septic tank
because as the sewage that's going in
the septic tank decomposes, it's giving
off ammonia which has nitrogen.
And nitrogen is an important 
component in plant growth.
And so as the ammonia is coming up, the roots are taking up the ammonia which has nitrogen in it and
gives it the nice green color and the
improved growth.
Dr. Hannah just explained 
something called the nitrogen cycle.
Which reminds me...
All of this is possible because of something you've probably heard of called photosynthesis.
And here's how it works.
Plants and some bacteria contain chlorophyl
which absorbs light energy and breaks water apart.
The oxygen from the water is
released into our atmosphere.
So the oxygen we breathe actually 
comes out of water molecules.
The hydrogen from the water is then
combined with carbon dioxide from the
atmosphere to build glucose sugar and
other carbohydrates.
This sugar is the main food for most cells.
So photosynthesis provides us with both
oxygen to breathe as well as food to eat.
