nutrient cycles and fertilisers 3.5 Flashcards
(26 cards)
define detritivores
animals such as worms or woodlice
eat and digest detritus
break tissues down to increase their surface area
for action by saprobionts.
define saprobionts
secrete enzymes for extracellular digestion.
create small soluble molecules that diffuse into saprophyte
requires specific conditions.
what conditions do saprobionts require
aerobic, non acidic, warm
what is mycorrhizae
associations between certain types of fungi and the roots of plants.
function of mycorrhizae
fungi act like extensions of the plant.
increase the surface area for absorption of water and minerals
hold water and nutrients near roots
help take up inorganic ions more readily.
3 effects of nitrogen containing fertilisers
reduced species diversity
leaching
eutrophication
how does N fertiliser reduce species diversity
favours growth of grasses, nettles, rapidly growing species which out compete other species.
2 negatives of N fertiliser causing leaching
high nitrate ion levels in water sources may be harmful to humans
high nitrate ion concentration leads to eutrophication.
cause of eutrophication
fertilisers leach off of farm fields into surrounding water course and sewage
contain dissolved nitrates and phosphates
what is eutrophication
effects of increase nutrients concentration on aquatic ecosystems.
two types of fertiliser
organic (farmyard manures)
inorganic (manufactured containing N and P)
4 advantages of organic fertiliser
steady supply of nutrients to plants
adds structure to soil (hummus)
useful means of disposing farm waste
nutrients not readily leached
3 disadvantages of organic fertiliser
offensive smells
may be difficult to spread
mineral release slow
3 advantages of inorganic fertiliser
conc form of nutrients - cost effective
nutrients release rapidly into soil
clean chemicals that lack odour of organic manure
4 disadvantages of inorganic fertiliser
readily leached from soil
can damage trophic levels in ponds/lakes
expensive to manufacture/buy
risk of fertiliser spreading to other areas
effect of eutrophication
excessive algal bloom
can reduce oxygen levels
due to decomposition of dead algae
using up oxygen
order of nitrogen cycle
atmospheric N2
nitrogen fixation
NH3
nitrification
NO2-
NO3-
assimilation (active transport)
plants
animals
ammonification
NH3
what is the process called of NO3- becoming atmospheric N2 called
denitrification
conditions of denitrification
anaerobic
conditions of both nitrogen fixing bacteria and nitrifying bacteria
aerobic
where are nitrogen fixing bacteria found
root nodules of legumes
soil
where are nitrifying bacteria found
soil
process of animal debris becoming ammonia
ammonification
process of atmospheric N2 becoming NH3
nitrogen fixation
