MICROORGANISMS-POST -7

April 20, 2020

What you see above is the nitrogen cycle. You have been introduced to the water cycle in the previous classes. What goes around comes around!!!

Good morning and welcome to another interesting day in the world of microbes.

We know that the atmosphere is made up of 78% nitrogen. However, we are unable to obtain this nitrogen that is required for our growth directly from the atmosphere. In this video we will see how plants obtain nitrogen from the atmosphere and thereafter how do we obtain this nutrition from plants.

https://www.youtube.com/watch?v=tCrgTV20BD4&t=22s

I hope you have understood how nitrogen is fixed by natural processes

Last year you did come across symbiotic bacteria. They live in the small swellings found on the roots of leguminous plants like groundnut. These bacteria convert atmospheric nitrogen into nitrates which are absorbed by the bacteria and provided to the plants for their growth.

When plants and animals decay, the decomposers help to break down the complex molecules and nitrogen is released in this process.

We have also seen in the video that when lightning strikes, the tremendous energy is used to break down the stable nitrogen molecule. When this nitrogen reacts with oxygen it forms nitric acid which is washed down with rain water. Here it reacts with limestone to form nitrates which are absorbed by the plants.

Manures also provide nitrogenous compounds required for the growth of plants. Plants grown using such natural fertilizers are said to be organically grown.

ARTIFICIAL FIXATION OF NITROGEN

 Fertilizers are also a source of nitrogen to the soil . Ammonium nitrate, urea etc are manufactured in factories to provide nitrogenous compounds to the plant and increase soil fertility.

Excess use of fertilizers is not desirable. Could you find the reason for this??

Terms to remember:
nitrifying bacteria - converts atmospheric nitrogen into nitrogenous compounds.
denitrifying bacteria - breaks down complex nitrogenous compounds into nitrogen that escapes into the atmosphere.

NITROGEN DIOXIDE                            AMMONIA                   
                      

                                                                                          AMMONIUM ION
                                     

I'm sure you must have been amazed at the role of simple bacteria in our lives. If it weren't for that humble microscopic bacteria present in air, water and soil the process of decomposition or rotting of substances wouldn't have taken place. Our planet would have been one garbage dump covered with dead organisms!!!