Use of natural & artificial fertilisers

Question 1

Do natural ecosystems need fertilisers? Explain the reason for your answer

Answer 1

No - They already have decomposed organisms so plants can absorb these minerals

Question 2

Do agricultural ecosystems need fertilisers? Explain the reason for your answer

Answer 2

Yes - crops are harvested + transported for consumption so soil is depleted of minerals (urine, faeces + dead remains are rarely returned to land)

Question 3

What are natural/organic fertilisers made from?

Answer 3

Consists of dead/decaying remains of plants/animals + animal waste e.g slurry + manure (made up of organic compounds)

Question 4

What are artificial fertilisers made from?

Answer 4

Contains pure chemicals as powders/pellets (inorganic compounds taken from rocks)

Question 5

What is leaching?

Answer 5

The washing away of water soluble compounds in the soil

Question 6

What is eutrophication?

Answer 6

The presence of excessive nutrients in a waterway causing death of plants + fish

Question 7

What is NPK and what is it made up of?

Answer 7

Fertiliser - made up of nitrates, phosphates + potassium

Question 8

How does nitrogen rich soils affect species diversity?

Answer 8

It reduces species diversity

Nitrogen rich soils favour the growth of particular species which then outcompete many other species

Question 9

What is the effect of eutrophication on organisms?

Answer 9

The enrichment of waterways with ions leads to death of fish + other animals due to an increased competition for light + water

Question 10

How do fertilisers affect productivity?

Answer 10

Fertilisers increase productivity
Fertilisers contain ions that promote plant growth by allowing synthesis of new biological molecules - leaf surface gets bigger so more photosynthesis can occur

Question 11

Describe the process of eutrophication

Answer 11

1. Increased nutrient concentration in the water increases growth of algae
2. The algae grow + cover the surface of the water (creates an algal bloom)
3. This prevents light from reaching the lower parts of water + this limits plant growth at the bottom of the river so plants die
4. The dead plants are broken down by saprobiontic bacteria causing their population to grow
5. These bacteria require O2 for respiration + so biological O2 demand increases
6. Concentration of O2 in the water is low + O2 becomes a limiting factor for aerobic respiration in fish - organisms die