Describe nitrogen cycle/ explain the circulation of nitrogen in the ecosystem.

-Nitrogen in the atmosphere is converted into nitrates/ ammonia through nitrogen fixation; by symbiotic bacteria e.g. Rhizobiun sp in the root nodules of legumes; by non-symbiotic bacteria and free living organism e.g. Azotobacter sp, Clostridium sp, some algae (e.g. Nostoc, blue green algae, Chlorella, Anabaena); and lightning; during thunderstorms and lightning, nitrogen gas combines with oxygen to form nitrogen (IV) oxide; nitrogen (IV) oxide dissolves in water to form nitric acid; which is deposited in the soil by rain. Nitric acid combines with chemical substances in the soil to form nitrates;
-Plants/ primary producers; absorb nitrate ions/ ammonium ions; from the soil and use them to manufacture amino acids/ plant proteins; in the process of photosynthesis;
-Animals/ herbivores/ primary consumers; feed on plants/ primary producers and digest and assimilate plant proteins into animal proteins;
-When animals and plants die they and animal wastes/ droppings are acted upon by saprophytes; releasing ammonium compounds in the process called ammonification/ petrification;
-Ammonium compounds are converted into nitrites; by nitrifying bacteria e.g. NItrosomonas sp,Nitrococcus sp; The nitrites are further converted into nitrates; by nitrifying bacteria e.g. Nitrobacter; in the process of nitrification;
-Nitrates are converted into nitrites/ ammonia compounds/ free nitrogen; by denitrifying bacteria e.g. Pseudomonas denitrificans, Thiobacillus denitrificans; in the process of denitrification;