Farming and fertilisers Flashcards
How does farming impact natural cycles?
reduces nutrients in soils, as it prevents them from being returned in decomposition by saprobionts
Why are fertilisers needed?
- (intensive) farming practices reduce the nutrients in soil
- fertilisers provide a source of nutrients for crop growth
What are artificial fertilisers made from?
inorganic matter/materials, usually containing nitrogen, phosphorus and potassium
What are 4 examples of natural fertilisers?
- manure
- compost
- crops left over from harvest
- sewage sludge
What feature of artificial fertilisers make them more environmentally damaging?
very soluble
What are 2 environmental impacts of artificial, nitrogen-containing fertilisers?
- eutrophication
- plant death (from high concentrations)
- leaching: leads to water pollution
- reduced species diversity: as conditions favour grasses, nettle etc.
How does excessive fertiliser cause plant death?
water moves out of the plant to an area with a lower WP by osmosis
Explain the process of eutrophication and why it is harmful
- fertilisers added
- fertilisers leach into water sources
- causes rapid growth of algae, preventing light from reaching plants below
- plants below cant photosynthesise (die)
- saprobionts decompose dead plants (aerobic)
- lower [O2], so organisms/fish die
What is leaching?
water dissolves chemicals and causes them to run off into water sources from soil (ponds, rivers, lakes etc)
How does cattle impact natural cycles?
- eat crops, so no nutrients can be replenished
Give 2 reasons why farming cattle is less efficient than farming crops
- energy lost between trophic levels
- energy lost in respiration and excretion (movement, temp. maintenance etc.)
Why is controlling the quantities of fertilisers important?
- beyond a certain point they do not improve productivity
- environmental impacts
Define eutrophication
the process by which nutrient concentrations increase in bodies of water
