SMES - Nitrogen Cycle (Lesson)
Nitrogen Cycle
Nitrogen and phosphorus are two of the most essential mineral nutrients for all types of ecosystems and often limit growth if they are not available in sufficient quantities. This is why the basic ingredients in plant fertilizer are nitrogen, phosphorus, and potassium, commonly abbreviated as NPK. A slightly expanded version of the basic equation for photosynthesis shows how plants use energy from the sun to turn nutrients and carbon into organic compounds:
Our atmosphere is composed of 78% Nitrogen (N2) and 21% Oxygen (O2). However, this atmospheric nitrogen cannot be used by organisms without some assistance. The nitrogen cycle is unique because it has stages during which bacteria help convert the nitrogen into useable forms. Nitrogen is essential for life because it helps to develop proteins, DNA, and RNA, and provides for plant growth. It can also be a limiting factor in plant growth.
The nitrogen cycle begins in the atmosphere as a gas N2. It then goes through many steps throughout its cycle.
For it to be made useable by organisms, N2 needs to be "fixed". This can occur by lightning or with the help of nitrogen-fixing bacteria. Nitrogen-fixing bacteria live in the soil and in nodules on the roots of legumes.
Watch the video below to learn more about Nitrogen fixation. A transcript is available on this page Links to an external site..
Self-Assessment Quiz - please answer the following questions.
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