LIFE SCIENCE

Detailed explanation-1: -Most nitrogen fixation occurs naturally, in the soil, by bacteria. In Figure 3 (above), you can see nitrogen fixation and exchange of form occurring in the soil. Some bacteria attach to plant roots and have a symbiotic (beneficial for both the plant and the bacteria) relationship with the plant [6].

Detailed explanation-2: -Bacteria in the soil convert those forms of nitrogen into forms plants can use. Plants use the nitrogen in the soil to grow. People and animals eat the plants; then animal and plant residues return nitrogen to the soil again, completing the cycle.

Detailed explanation-3: -The major source of nitrogen is the atmosphere. It exists as a colorless, odorless, nontoxic gas and makes up about 78 percent of the atmosphere. Nitrogen is also found in the Earth’s crust as part of organic matter and humus.

Detailed explanation-4: -Nitrogen is an element that is found in both the living portion of our planet and the inorganic parts of the Earth system. Nitrogen moves slowly through the cycle and is stored in reservoirs such as the atmosphere, living organisms, soils, and oceans along the way. Most of the nitrogen on Earth is in the atmosphere.