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Biology Form 5 Science
Chapter 6: ECOLOGY
NITROGEN CYCLE
- Nitrogen is present in the atmosphere as NO2 gas
- Which in this form is useless to green plant because it is innert or inactive*plant absorb nitrogen in the form of nitrate and ammonia salt which is used to manufacture their protein
- The nitrate dissolve in soil water and are taking in by plant through the root hair
- Animals obtain the nitrogen the need by feeding another plant or on other animals
- Putrefaction: it is when protein znd nitrogenous compound are broken down to inorganic ammonia salt. Saprophytic soil bacteria and fungi take part in this process and decay
- Nitrification: it is a process by which Nitrosomonas a soil bacteria oxidises ammonia and ammonium salt to nitites while nitro bacteria oxides nitrites to nitrates
- Dentrification: some bacteria present in the soil bacteria reduces nitrale in the soil to gaseous nitrogen. Nitrites are also lost from the top soil by leaching
- Nitrogen fixation: it is the process by which ammonia and nitrogenous compound are added to the soil from free gaseous nitrogen in the air. It is carried out by the nitrogen fixing bacteria. E.g azobacteria that is free living in the soil and the rhizobium that live in root nodules. During thunder stormes nitrate are also added to the soil
par Claude Foumtum