Where has that carbon atom been? The carbon cycle is a complex cyclical process through which all of the carbon atoms in existence rotate.
Plants absorb the nitrate ions by diffusion and active transport. The plants need the nitrogen for the synthesis of proteins and other compounds. The nitrogen compounds are passed through the food chain as other organisms feed on the plants and each other.
Waste products (undigested food, urine and faeces) and dead organisms which contain nitrogen compounds are added to the soil.
The decomposers - certain soil bacteria and fungi e.g. ammonifying bacteria - break down proteins in dead organisms and animal wastes, releasing ammonium ions.
Nitrification is a two-step process that is carried out by the nitrifying bacteria. Ammonia or ammonium ions are oxidized first to nitrites and then to nitrates.
Nitrates are reduced to nitrogen gas by denitrifying bacteria.
Nitrogen fixing bacteria fix 60% of nitrogen gas.
Nitrogen is required by all living organisms for the synthesis of proteins, nucleic acids and other nitrogen containing compounds. The Earth’s atmosphere contains almost 80 % nitrogen gas. It cannot be used in this form by most living organisms until it has been fixed, that is reduced (combined with hydrogen), to ammonia.
The nitrogen cycle is a series of processes that convert nitrogen gas to organic substances and back to nitrogen in nature. It is a continuous cycle that is maintained by the decomposers and nitrogen bacteria. The nitrogen cycle can be broken down into four types of reaction and micro-organisms play roles in all of these.