Oh the places we’ll go on our nitrogen cycle tour! Nitrogen is an element that cycles through you, me, plants, and other organisms. This lesson will not only follow nitrogen on this cycle, but will also share some nitrogen facts!
Definition of the Nitrogen Cycle
As you bite into your scrumptious turkey, lettuce, and tomato sub sandwich you’re probably not thinking even though these nitrogen atoms used to be in cow poop, this sandwich is still going to be delicious!Sorry if I ruined your lunch, but those nitrogen atoms are quite the sightseers, visiting the air, microorganisms, plants, animals, and the soil though the nitrogen cycle, or the circulation of nitrogen on Earth. Nitrogen is one type of atom, like oxygen, carbon, and hydrogen.
Let’s follow some nitrogen atoms through the nitrogen cycle to see where they go!
Steps of the Nitrogen Cycle
You are surrounded by nitrogen! In fact, 78% of the air you breathe is nitrogen, but how does the nitrogen from the air get into your turkey sandwich? Good question! Well, here are the stops a nitrogen atom would take on its voyage through the nitrogen cycle:1. Let’s start with the air you are breathing. When nitrogen is in the air it is called atmospheric nitrogen and comes in the form of N2, which means two nitrogen atoms stuck together. Plants can’t do a whole lot with atmospheric nitrogen, but microorganisms like nitrogen-fixers, which are special bacteria that can change the nitrogen into a useable form through a process called nitrogen fixation. Let’s take a look at how nitrogen fixation takes place.
- Atmospheric nitrogen makes its way into the soil where nitrogen-fixing bacteria on the roots of some plants change it to ammonium (nitrogen attached to hydrogen atoms, NH4+). There are also some free-living bacteria (not on the roots of plants) that are nitrogen-fixers.
- Lightning can also change atmospheric nitrogen into nitrogen oxides, another type of nitrogen attached to oxygen atoms. This makes up only a small percentage of nitrogen fixation.
2. Bacteria and archaea (another type of microorganism) in the soil change the ammonium into nitrites (NO2–) and then nitrates (NO3–) through nitrification, which is, in essence, when bacteria change ammonium into nitrates.
Nitrates are nitrogen attached to oxygen atoms.3. Now that the atmospheric nitrogen has been changed into nitrates, let’s see what happens next.
Assimilation is when plants use the nitrogen for all sorts of things like building leaves or making DNA (deoxyribonucleic acid). Animals and other organisms eat the plants, and the nitrogen gets incorporated into those bodies as well.4. Eventually plants, animals, and other organisms die and decay, releasing nitrogen back into the soil.
Bacteria and fungi (mushrooms, for example) help break down the dead organisms, and through ammonification, nitrogen is turned back into ammonium. The ammonium is turned back into nitrates by bacteria (you basically go back to step 2).5.
Special bacteria can turn nitrates back into atmospheric nitrogen through a process called denitrification, which is how nitrogen in the soil is released into the atmosphere again. And, you are back at step 1!So how did the nitrogen atoms in your turkey sandwich get there? Nitrogen from the air was turned into nitrogen that plants could use, like the lettuce and tomato on your sandwich. One day a turkey ate some of the plants and the nitrogen was incorporated into its body.
But before all that occurred, the same nitrogen atom was eaten by a cow and released as feces where it returned to the soil (only to land in your turkey sandwich a few cycles later)!
Nitrogen Cycle Facts
The nitrogen cycle is happening as you sit and read this lesson, and without it, you wouldn’t have nitrogen in your body (which would be unfortunate… you couldn’t live without nitrogen). Let’s look at some awesome nitrogen and nitrogen cycle facts!
- Nitrogen is used in fertilizer, which makes plants grow faster.
- Nitrogen is the fifth most abundant element in the entire universe.
- Nitrogen is odorless and colorless.
- Too much nitrogen (overuse of fertilizers) can make people (and other organisms) sick.
- Nitrogen-fixing bacteria can be found on the roots of legumes like soybeans. The ancient Romans would rotate their legumes every four years.
This replaced nitrogen in the soil and resulted in better crops.
- Cyanobacteria is also a nitrogen-fixer and is often called blue-green algae (even though it isn’t algae at all).
- Your body needs nitrogen for such things as blood, skin, muscles, and DNA.
- Liquid nitrogen is actually atmospheric nitrogen that is a liquid at temperatures between -346; F and -320; F (so it is really cold).
- 3% of your body weight is nitrogen.
Wow! I am exhausted from our nitrogen cycle tour: the air, the soil, plants, animals, and bacteria! Even you need it, for your skin, muscles, and even DNA to work properly.
Without the nitrogen cycle, which if you recall, is the circulation of nitrogen on Earth, life couldn’t exist. So, let’s review some important stops from our nitrogen tour!Nitrogen fixation is how nitrogen is transformed from N2, or atmospheric nitrogen into ammonium. This is done with the help of nitrogen-fixers, which are special bacteria that can change the nitrogen into a useable form through a process called nitrogen fixation.
This bacteria can be found on many places, including legumes, on plant roots, and even in blue-green algae.Nitrification is when bacteria change ammonium into nitrates.Assimilation is when nitrogen is incorporated into living organisms.Ammonification is when nitrogen from dead and decaying organisms is changed into ammonium.Denitrification is how nitrogen from the soil is returned to the atmosphere.I hope you enjoyed our tour;now enjoy that sandwich!