threats to biodiversity-- fertilizer
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which organisms require oxygen?
aquatic and terrestrial
what is dissolved oxygen?
measure the amount of oxygen present in water
low dissolved oxygen = _____ organisms survive
fewer
what is biological oxygen demand (BOD)?
measure the oxygen used by micro organisms in a given body of water
high BOD = water is very ____, and ____ organisms survive
polluted / fewer
what 3 nutrients does fertilizer add to soil, which helps plants grow?
• nitrogen • phosphorus • potassium
what do plants continuously remove?
nutrients from soil
in a natural ecosystem, how are nutrients continuously replenished?
decomposition of dead organisms
in a farmland / lawn, where do nutrients come from?
fertilizer
why does a farm / lawn need fertilizer?
there are very few dead organisms around
what happens to excess nutrients from fertilizer? (step 1)
they drain with water and go into ponds and rivers
why does algae in the water grow rapidly? (step 2)
the extra nutrients cause eutrophication
when algae die, the decomposer uses ___________ to _____ the algae (step 3)
all the oxygen / decompose
what 2 other things can cause eutrophication?
• manure - sewage
some algae can also be ___ to animals and humans
toxic
what 4 ways can fertilizer usage be reduced?
• no tillage farming • crop rotation • crop selection • use alternative strategies
what is no tillage farming?
leave the remains of crops on the ground after harvest to let the decomposers decompose the crop remains into nutrients
what is crop rotation?
alternate crops that use a lot of nutrients with crops that produce nutrients
which plants are less profitable?
crops that produce nutrients such as soybeans / peas / alfalfa
what is crop selection?
select crops that need less fertilizer
what is an example of an alternative strategy?
adding charcoal to soil to help plants grow better– they enhance the nutrient uptake