Nutrient cycles Flashcards
Why do we need nitrogen
Proteins, ATP, nucleic acids
Nitrogen fixation
Industrial or lightning
Free living NFB - gaseous nitrogen > ammonia, for amino acids, released upon death
Mutualistic NFB - live on nodules on roots, obtain carbs in exchange for amino acids
Ammonification
Production of ammonia from nitrogen containing compounds
Saprobionts feed on bacteria + faeces, release ammonia, forms ammonium ions
Nitrogen returns to non-living component of ecosystem
Nitrification
Ammonium ions to nitrates Carried out by nitrifying bacteria 1 - ammonium ions to nitrites (NO2-) 2 - nitrites to nitrates (NO3-) Requires o2 so spaces needed in soil Requires good drainage
Denitrification
Anaerobic denitrifying bacteria convert nitrates to nitrogen gas
Lost to the air
Found in waterlogged soil
Phosphorous cycle (P)
P in sedimentary rocks
Rocks formed in sea and pushes to surface via geographical activity
Weathering + erosion = P released
P ions dissolve and are taken up by plants
Passed into animals during feeding
Excretion + death > bacteria + fungi, P in hard tissues are hard to break down
Broken down into soil and water
Combine with sedimentary rock
Mychorrizae
Mutualistic fungi
Gains carbs, gives water
Increases SA for water and mineral absorption
Acts like a sponge and holds water and mineral ions close to the roots
Fertilisers
Natural:
- manure, bone meal
- cheap/free
- exact minerals and proportions can’t be controlled
Artificial:
- expensive
- exact minerals and proportions
- more water soluble leading to leaching
What is leaching
Nitrogen containing substances being washed away into ponds
Eutrophication
Leaching Bacteria and algae grow Algae absorbs light -light becomes limiting factor Plants below surface die -no lack of organic matter Saprobionts increase -more o2 needed -o2 becomes limiting factor Aerobic organisms die -nitrates released Anaerobic organisms increase -more dead material decomposed -more nitrates Pond becomes putrid
