Fertilisers And Eutrophication

Question 1

Artificial fertilisers.

Answer 1

Inorganic.

Contain pure chemicals (e.g. ammonium nitrate) as powders or pellets.

Question 2

Natural Fertilisers

Answer 2

Organic.

Include manure, composted vegetables, crop residues and sewage deluge.

Question 3

Environmental issues of fertilisers.

Answer 3

More fertiliser is applied than plants need which can lead to fertilisers leaching into waterways.

Leading to eutrophication.

Changes balance of nutrients in the soil - too much of particular nutrient can cause crops and other plants to die.

Question 4

Leaching.

Answer 4

When water-soluble compounds in the soil are washed away, e.g. by the rain or irrigation systems. Often washed into nearby ponds or rivers.

Lead to eutrophication.

More likely to occur if fertiliser is applied before heavy rainfall.

Less likely in natural fertilisers.

Question 5

Eutrophication.

Answer 5

1. Mineral ions leached from fertilised fields stimulate 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 numbers of bacteria reduce oxygen concentration in water by carrying out aerobic resp.
5. Fish and other aquatic organisms die because there isn’t enough dissolved oxygen.