biogeochemical cycles - nitrogen cycle
- Created by: student111319
- Created on: 04-04-23 19:03
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the nitrogen cycle
- the nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates amoung the atmosphere, terrestrial + marine ecosystems
- processes: fixation, ammonification, nitrification, denifriciation
- nitrogen is most abundant element in atmosphere
- nitrogen is abudant but need to undergo processes before is becomes available, accessible + useable, need bacteria to convert it into nitrogen containing compounds
what is the importance of nitrogen?
- nitrogen important for plant growth (structure), plant food processing + the creation of chlorophyll
- without enough nitrogen in plant it cannot grow taller/produce enough food - this have impact on commercial crop growth
how does nitrogen imapct the soil?
- without enough plant growth is negatively affected
- too much nitrogen plants produce excess biomass/organic matter e.g. leaves but not produce enough root strucuture
- very high levels of nitrogen absorbed from soils can poison farm animals that eat them
whats the difference between nitrifying bacteria, denitrifying bacteria, nitrifying-fixing bacteria + decomposing the bacteria?
- nitrifying bacteria - converters of soil ammonia to nitrates, compound usable by plants
- denitrifying bacteria is the soil break down nitrates + return nitrogen to the air
- nitrogen fixing bacteria present in soil/in plant roots that change nitrogen gases from the atmosphere into solid nitrogen compounds that plants can use in the soil
- decomposers convert the nitrogen found in other organisms into ammonia + return it to the soil
plants uptake nitrogen compound once nitrogen is converted into compounds like ammonium + nitrate, these be taken up from the soils by plants + then nitrogen be used to from macromolecules e.g. protiens
Fixation:
- nitrogen in its gaseous from N2 cant be used by living things, it has be converted/fixed to a more useable form through a process called fixation, are three ways nitrogen be fixed to be more useful for living things:
- biologically - nitrogen gas diffuses into soil from the atmosphere + species of bateria convert this nitrogen into ammonium
- NH4+ derived from ammonia by combination with a hydrogen ion, a nitrogen compound taken up by plants from soils
- ions (NH4+) which be used by plants, legumes e.g. clover often grown by farmers as have nodules on their roots that contain nitrogen fixing bacteria
Decomposition:
- plants take up nitrogen compounds through their roots, animals obtain these compounds when eat plants, when plants + animals die/when animals excrete wastes, the nitrogen compounds in the organic matter re-enter the soil where they are broken down by microorganisms - decomposers, this decomposition produces ammonia which then go through the nitrification process
nitrification:
- nitrifying bacteria in the soil convert ammonia into nitrite (NO2-) + then into nitrate (NO3-) - process called nitrification
- compounds e.g. nitrate, nitrite, ammonia + ammonium can be taken up from the soils by palnts + then used in the formation of plant + animal proteins
Denitrification:
- process where bacteria in soil breaks down nitrates into atmospheric nitrogen gas
- completes the nitorgen cycle by converting nitrate back into gaseous nitrogen, denitrifying bacteria are…
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