fertilisers and eutrophication

Question 1

how are nutrients lost when crops are harvested

Answer 1

when crops are harvested from a field they are taken away instead of being allowed to decompose there, this means they take away the mineral ions with them such as phosphates and nitrates and these arent returned to the soil in the nitrogen or phosphorus cycle. phosphates and nitrates are also lost from the system when animals or animal products are removed from an ecosystem

Question 2

why are fertilisers added to soils

Answer 2

to replace lost nutrients

Question 3

what are the 2 types of fertilisers

Answer 3

1) artificial fertilisers - inorganic and they conatin pure chemicals as powders or pellets
2) naturtal fertilisers - contain organic matter and include manure, composted vegetables or crop residue

Question 4

give examples of envirmental issues that using fertilisers can lead to

Answer 4

if more fertiliser than a plant can handle is given, the excess leaches into waterways. using too much fertiliser can also change the balance of the nutrients in the soil which can lead to crops dieing

Question 5

what is leaching

Answer 5

when water-soluble compounds in the soil are washed away by rain, often washed into ponds or lakes

Question 6

when is leaching more likely to occur

Answer 6

before heavy rainfall

Question 7

inorganic ions in chemical fertiliers are relatively soluble, what does this mean in terms of excess minerals

Answer 7

minerals that aren’t used straight away are more likely to to leach into waterways.

Question 8

why are the excess minerals in natural fertilisers less likely to be leach

Answer 8

because the minerals are part of organic compounds and need to be broken down by decomposers before they can absorbed by plants, the uptake is a lot more controlled

Question 9

why is the leaching of phosphates less likely than nitrates

Answer 9

because phosphates are less soluble in water

Question 10

what are the steps for eutriphication

Answer 10

1) excess minerals and ions leach into ponds and lakes to stimulate rapid growth of algae
2) the large amounts of algae growing blocks out the sunlight in the pond or lake
3) plants die as they cant photosynthesis enough
4) bacteria break down the dead plant matter through aerobic respiration which decreases dissolved oxygen concentration in the water
5) fish die due to not enough dissolved oxygen in the water