Natural Resources Class 9 Science - The Biogeochemical Cycles - Water Cycle and Nitrogen Cycle 

Natural Resources Class 9 Science - The Biogeochemical Cycles - Water Cycle and Nitrogen Cycle.
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In this video, we will learn about Biogeochemical cycles, Water cycle and Nitrogen cycle.
What is The Bio Geo chemical Cycles?
It is movement of chemical substances due to interaction of biotic and abiotic components of earth.
There are two types of biogeochemical cycles -
1) Water Cycle and 2) Nitrogen Cycle.
What is water cycle?
The process of water cycle -
1) Evaporation and Transpiration:
Water from seas and ocean evaporates due to the heat of the sun. Water converts into vapors and reach high in the atmosphere. Excess of water from plants, undergoes transpiration i.e. water is released out of plant body in form of vapors; these vapors rises up in the atmosphere.
2) Condensation and precipitation: Vapors reaching high in the atmosphere, undergo condensation and turns into water droplets. These water droplets, collect together and makes a cloud. Clouds are also carried from one place to another due to air. When cloud become heavy it fall down in the form of rain. In condition of lower temperature, precipitation occurs, and water drops freeze, in such case, there occurs snowfall or hailstones.
3) Absorption and percolation: Water falling on the ground get absorbed into ground. This water gets drain through the rocks and meets the ground water. Water running off from the hills meets the flowing water. Underground water and flowing water somewhere meets the seas and oceans. This, completes water cycle.
Nitrogen cycle -
What is nitrogen cycle?
Nitrogen occurs as 78% part of atmosphere. The atmospheric nitrogen, is difficult to use hence, there is necessity to fix this nitrogen in its useful form.
The process of nitrogen cycle -
1) Fixation - It is first step of nitrogen cycle. In which free or elemental nitrogen is fixed by certain bacteria and converted into ammonium is called fixation.
2) Nitrification - Bacteria then converts ammonium into nitrates is called nitrification.
3) Assimilation - In which process, plants absorbs nitrogen from the soil through roots is called assimilation.
4) Ammonification - When plants and animals die, fungi and bacteria converts their nitrogen into ammonia and transfer it to nitrogen cycle.
5) Denitrification - There are special bacteria that converts extra nitrogen from the soil into it's elemental form and put them back into the air.