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Nitrogen Cycle

Advanced Knowledge of Nitrogen CycleComponents of Air- NitrogenImportance of components of airNitrogen Fixation and Nitrogen CycleBiogeochemical Cycle - Nitrogen CycleNitrogen CycleNitrogen Cycle

Transcript

  • 0:4Nitrogen is a very very important element for all plants and animals.
  • 0:9It is an essential component for the formation of proteins, vitamins
  • 0:14and also it is important to form nucleic acids which forms our genes.
  • 0:19So, needless to say that these substances like proteins, vitamins, nucleic acids and many other
  • 0:24are very important for all plants and animals.
  • 0:28Talking about nitrogen,
  • 0:30you know that it is the most abundant gas which is present in the atmosphere.
  • 0:36But still,
  • 0:37this gas is not available for plants and animals.
  • 0:41So, how do they get this?
  • 0:43They get it with the help of some special microorganisms which are present in the soil.
  • 0:49These microorganisms, they fix this nitrogen from the atmosphere into the soil.
  • 0:56So, when they fix it,
  • 0:57does it happen that all the nitrogen in atmosphere exhaust?
  • 1:1Well no!
  • 1:3There are some different kind of microorganisms present in the soil,
  • 1:8which reconvert this fixed Nitrogen back in to the gaseous nitrogen in the atmosphere.
  • 1:15And this cycle,
  • 1:16the cycle of conversion of nitrogen into nitrogenous compound and these compounds back into the gaseous nitrogen,
  • 1:23it keeps on going.
  • 1:25As it keeps on going, it forms a chain or a cycle kind of thing which you call nitrogen cycle.
  • 1:31So, in this lesson we are going to discuss this nitrogen cycle in detail.
  • 1:36So, to start with, let's first talk about the nitrogen fixation.
  • 1:41Nitrogen fixation, it is simply the conversion of gaseous nitrogen into the nitrogenous compounds in the soil.
  • 1:51This can be done in two ways,
  • 1:54either atmospherically or biologically.
  • 1:58So, let us discuss them one by one.
  • 2:0So, in atmosphere this nitrogen, it is fixed by the enormous energy of lightning.
  • 2:8So, during lightning
  • 2:10the high energy or the enormous energy, it combines the nitrogen and oxygen together to form a nitrogenous compound.
  • 2:20This nitrogenous compound, when it rains, it gets dissolved with the rain and falls on the earth surface.
  • 2:28As soon as it falls on the earth surface,
  • 2:32it gets mixed with the soil.
  • 2:34So, from the soil, now the plants they can easily absorb this nitrogen in the form of nitrogenous compound by the roots.
  • 2:44Similarly, when we talk about biological nitrogen fixation,
  • 2:50in biological nitrogen fixation, there are some bacterias and blue green algae present in the soil.
  • 2:57These bacterias and blue green algae, they fix the nitrogen,
  • 3:1they fix the atmospheric nitrogen in the form of ammonia in the soil.
  • 3:6Now, a different type or a different category of bacteria, they convert this fixed ammonia into the usable nitrogen compounds.
  • 3:16So, again the soil has these nitrogenous compounds.
  • 3:20As soon as they get available in the soil,
  • 3:22they can be readily absorbed by the plants.
  • 3:25So, the plants, they absorb this usable nitrogenous compounds
  • 3:30to make their protein and other nitrogenous substances like we just discussed.
  • 3:36So, we all now know that animals, they feed upon plants.
  • 3:42They feed upon plants for their nutrition.
  • 3:45So, these plants when they are eaten up by the animals,
  • 3:49the animals they get the protein from these plants.
  • 3:53So, now animals, they have got the proteins and other nitrogenous substances of course from these plants.
  • 4:1So, over a period of time when these animals and plants, they die,
  • 4:5they get mixed again with the soil.
  • 4:8So, when they get mixed with the soil,
  • 4:11you know that there are some other microorganisms present in the soil which helps in decomposition of dead plants and animals.
  • 4:21During decomposition these microorganisms such as bacteria and fungi,
  • 4:27they reconvert or they bring back the nitrogenous compounds which were present in the dead plants and animals
  • 4:35back into the soil.
  • 4:37So, the soil now again has this nitrogenous compound.
  • 4:41These nitrogenous compounds, they can again be taken up by some other plants for their growth
  • 4:49or there are some other microorganisms present in the soil, there are some other bacterias present in the soil
  • 4:56which reconvert this fixed nitrogen, this nitrogenous compound from the soil back into the gaseous nitrogen.
  • 5:7So, they help in basically denitrification.
  • 5:10So, first of all we saw the nitrogen fixation, it is the conversion of gaseous nitrogen into the nitrogenous compound.
  • 5:17Now, these bacteria's they are reconverting this nitrogenous compound into the atmospheric nitrogen.
  • 5:24So, you have just seen that this thing, this whole process goes on in a cycle kind of a way.
  • 5:31So, that is why we call it nitrogen cycle.
  • 5:34So, now when you have understood what is nitrogen cycle,
  • 5:38now, let's quickly recap to memorize it.
  • 5:41So, we have first of all seen that atmospheric nitrogen it can be converted into the nitrogenous compounds in two ways,
  • 5:48either by lightning or with the help of certain bacteria's.
  • 5:52Next, we have seen that as soon as this usable nitrogen is available,
  • 5:57plants readily absorb them
  • 5:58and make some substances out of this.
  • 6:1The animals they feed upon plants
  • 6:3to get this protein and other nitrogenous compounds
  • 6:6and when they both die, they get mixed with the soil.
  • 6:9When they get mixed with the soil, the decomposing bacteria's and fungi,
  • 6:15they decompose them to bring back the nitrogenous compound into the soil.
  • 6:20This nitrogenous compound,
  • 6:22it can either taken up by the other plants to grow or it can be converted back into the gaseous nitrogen with the help of certain bacteria's.
  • 6:32So, isn't it easy?
  • 6:33It's just a simple cycle, right?
  • 6:35I hope you will remember it for a longer time.

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