Let's start off linearly, mate, starting with nitrogen fixation. This process occurs when special bacteria convert atmospheric nitrogen (N2) into ammonia (NH3).
When an organism dies, or if an animal defecates, decomposers such as bacteria and fungi convert the nitrogen (from said dead organism or feces) back into ammonium (NH4+) so that it can re-enter the nitrogen cycle.
Well kiss me barnacle and call me Pikachu, it seems I get to talk to ye after all. I be Captain Nitrogen and since ye spent so long to get here... why don't I teach you about the nitrogen cycle?
Secondly, ammonia is toxic to plants. Therefore, it must be converted into a more useful form. Luckily, bacteria in the soil convert ammonia to nitrites (NO2) or nitrates (NO3).
After being converted, plants then absorb the nitrites/nitrates from the soil into their roots.
Finally, the extra nitrogen in the soil is converted back into atmospheric nitrogen by the previously mentioned bacteria, starting the cycle all over nitrogen again.
Thank you, dearly. Anyways, I forgot to mention an important factor you must heed in order to grasp an important understanding of the carbon cycle...how humanity impacts it.
For more than a century, mankind has been using fossil fuels which greatly impact the c.c. by burning them (fossil fuels) which in turn produces massive amounts of CO2 into the atmosphere; to make the situation worse, humans have been chopping down plants by the acres in order to make way for cattle ranches for beef. If this repetitive cycle continues on, plants may not be able to keep up with how much they need to take in to continue their natural cycle! Only time will tell...either way, thank you for your attention!
Well I hope ye learned a ton from me lecture and- Oh! It seems we be having company.