Nitrogen Fixation
- Nitrogen-fixating bacteria fix atmospheric nitrogen into organically-usable
ammonia - necessary for the development of proteins.
- Other bacteria convert ammonia into nitrates.
- Rhizobium, a nitrogen-fixating bacteria exists in a mutualistic relationship with
plant roots, infecting them with hair tendrils that absorb some of the plant’s
carbohydrates and return ammonia.
The Process of Denitrification
1. Rhizobium converts nitrogen to ammonia.
2. Chemoautotrophic Nitrosomonas convert ammonia to nitrite, utilising the energy
from this inorganic reaction for carbon fixation.
3. Nitrobacter converts nitrite to nitrate (an organic molecule), utilising the energy
from this inorganic reaction for carbon fixation.
4. Denitrifying bacteria convert nitrate to atmospheric nitrogen to complete the
cycle and thus limiting the soil of nitrogen (denitrification). They convert nitrate
to nitrogen when oxygen is limited. Plants can also use nitrates for amino acids.
Application: Waterlogging Leads to Denitrification
- Waterlogging reduces oxygen supply, resulting in excess denitrification and
eutrophication.
Application: “Carnivorous” Plants are Adapted to Low Nitrogen Soils
- “Carnivorous” plants are adapted to waterlogged soils and obtain nitrogen
through the digestion and fixation of other organisms via external digestion
through tentacles. They are not technically carnivorous as they still obtain
carbohydrates through photosynthesis.
The Phosphorus Cycle
- Phosphorus is required for nucleic acids, ATP and other vital organic structures. A
large phosphorus store is phosphorite - a sedimentary rock. It is released through
erosion and stored through sedimentation. The process is thus slower than the
nitrogen cycle.
- Plants uptake phosphorus in the form of phosphates.
Effect of Agriculture on Soil Phosphorus
- A phosphorus-based fertiliser is obtained through the mining of phosphates.
Waterlogging and run-off containing phosphates can lead to eutrophication.
Peak Phosphorus Production
- Nitrogen-fixating bacteria fix atmospheric nitrogen into organically-usable
ammonia - necessary for the development of proteins.
- Other bacteria convert ammonia into nitrates.
- Rhizobium, a nitrogen-fixating bacteria exists in a mutualistic relationship with
plant roots, infecting them with hair tendrils that absorb some of the plant’s
carbohydrates and return ammonia.
The Process of Denitrification
1. Rhizobium converts nitrogen to ammonia.
2. Chemoautotrophic Nitrosomonas convert ammonia to nitrite, utilising the energy
from this inorganic reaction for carbon fixation.
3. Nitrobacter converts nitrite to nitrate (an organic molecule), utilising the energy
from this inorganic reaction for carbon fixation.
4. Denitrifying bacteria convert nitrate to atmospheric nitrogen to complete the
cycle and thus limiting the soil of nitrogen (denitrification). They convert nitrate
to nitrogen when oxygen is limited. Plants can also use nitrates for amino acids.
Application: Waterlogging Leads to Denitrification
- Waterlogging reduces oxygen supply, resulting in excess denitrification and
eutrophication.
Application: “Carnivorous” Plants are Adapted to Low Nitrogen Soils
- “Carnivorous” plants are adapted to waterlogged soils and obtain nitrogen
through the digestion and fixation of other organisms via external digestion
through tentacles. They are not technically carnivorous as they still obtain
carbohydrates through photosynthesis.
The Phosphorus Cycle
- Phosphorus is required for nucleic acids, ATP and other vital organic structures. A
large phosphorus store is phosphorite - a sedimentary rock. It is released through
erosion and stored through sedimentation. The process is thus slower than the
nitrogen cycle.
- Plants uptake phosphorus in the form of phosphates.
Effect of Agriculture on Soil Phosphorus
- A phosphorus-based fertiliser is obtained through the mining of phosphates.
Waterlogging and run-off containing phosphates can lead to eutrophication.
Peak Phosphorus Production
