Fertilisers and eutrophication

Question 1

What causes a loss of nutrients?

Answer 1

When crops are harvested, the minerals they contain are not returned to the soil
Phosphates and nitrates are lost when animals or animal products are removed from the land

Question 2

What is the purpose of fertilisers?

Answer 2

Replace the lost minerals so more energy from the ecosystem can be used for growth increasing the efficiency of energy transfer

Question 3

What are the two types of fertiliser?

Answer 3

Artificial

Natural

Question 4

What are artificial fertilisers?

Answer 4

Inorganic

Contain pure chemicals

Question 5

What are natural fertilisers?

Answer 5

Organic

Include manure, composted vegetables, crop residues

Question 6

What is leaching?

Answer 6

When water-soluble compounds in the soil are washed away

Question 7

What causes leaching?

Answer 7

More fertiliser is applied than the plants need or are able to use

Question 8

When is leaching more likely to occur?

Answer 8

If fertiliser is applied just before heavy rainfall
Inorganic ions in chemical fertilisers are relatively soluble so excess minerals that are not used immediately are more likely to leach into waterways

Question 9

What is leaching less likely with? Why?

Answer 9

Natural fertilisers
Nitrogen and phosphorus are still contained in organic molecules that need to be decomposed by microorganisms before they can be absorbed into the soil

Question 10

Outline the process of eutrophication.

Answer 10

1) mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds and rivers
2) Large amounts of algae block light from reaching the plants below
3) Eventually the plants die because they’re unable to photosynthesise enough
4) Bacteria feed on dead plant matter. Increased number of bacteria reduce the oxygen concentration in the water by carrying out aerobic respiration