Question

Leguminous plants improve soil fertility. How?

Answer 1

Hint: In leguminous plants the rhizobium bacteria is present. Rhizobium bacteria for symbiotic Association with the plants these microscopic bacteria change the atmospheric nitrogen into a form that can be easily taken by plants.

Complete answer :
The leguminous plant restores the lost nutrition plant. It is generally seen that legumes are grown in a plant that is growing in a field that has an efficiency of Nutrition. Leguminous plants are of great interest and these plants enrich the soil with natural fertilizers, which is ammonia. Ammonia is then converted into nitrogen, which can be taken up by the plants easily. What happens is the nitrogen present in the atmosphere; it cannot be directly taken up by the plants in its molecular form. If legumes are not present then these plants generate nitrogen deficiency.

In Leguminous plants, nitrogen-fixing bacteria for example rhizobia helps in nitrogen fixation. These bacteria infect the roots of the leguminous plant and nodule formation takes place. Atmospheric nitrogen is molecular nitrogen, which is present in a relatively non-reactive molecular form which is useless to few microorganisms In the process of Nitrogen fixation, molecular nitrogen (N$_2$) converts into ammonia (NH$_3$). Ammonia is further assimilated into amino acids, nucleotides, and other cellular constituents such as vitamins and hormones. Nitrogen fixation is oxygen sensitive. As it is a symbiotic relationship both bacteria and plants are benefited by the process. A plant that contributes to nitrogen fixation and to improve soil fertility is the family of legume plants. These include Soybean, peanut, alfalfa, etc.

Note: Organic compounds and secondary metabolites are called flavonoids. This helps the bacteria to get attracted towards the roots of the plant. Apart from rhizobia, other nitrogen-fixing bacteria are cyanobacteria and Anabaena and nostoc.