fertilisers and eutrophication

Question 1

why are fertilisers added to the soil ?

Answer 1

• added to replace the nitrate and phosphate ions lost when plants are harvested

Question 2

what does it mean when plants are harvested ?

Answer 2

• they are removed from nutrient cycles as crops

Question 3

what are the 2 types of fertilisers ?

Answer 3

• natural (animal manure)
• artificial (inorganic chemicals )

Question 4

advantages of natural fertilisers ?

Answer 4

• they are cheaper
• and often free if the farmer owns animals

Question 5

what is a disadvantage of natural fertilisers ?

Answer 5

• the exact minerals and proportions cannot be controlled

Question 6

what is an advantage of artificial fertilisers ?

Answer 6

• they are chemicals created to contain exact proportions of minerals to meet the needs of the crops that you are growing

Question 7

what is a disadvantage of artificial fertilisers ?

Answer 7

• inorganic substances are more water soluble
• so the ions will dissolve in the (rain water) surrounding the soil
• more likely to leach into the near by rivers

Question 8

what kind of impact does leaching have on the environment ?

Answer 8

• negative impact on the environment

Question 9

because the inorganic substances are more water soluble, what is the benefit of this ?

Answer 9

• the nitrates and phosphates are more easily absorbed by the plant

Question 10

what does leaching mean ?

Answer 10

• when water soluble compounds are washed away, often into rivers or ponds

Question 11

what doe nitrogen fertilisers leaching into waterways cause ?

Answer 11

• eutrophication

Question 12

what is eutrophication ?

Answer 12

• when nitrates leached from fertilised fields stimulate growth of algae in ponds

Question 13

what does the excessive growth of algae cause ?

Answer 13

• it creates a blanket on the surface of the water which blocks out light

Question 14

as a result of the algae growing on the surface of the water, what does this do to the plants ?

Answer 14

• the plants below cannot photosynthesise and die

Question 15

what do the dead plant material provide ? and what do they do ?

Answer 15

• provides a food source for bacteria within the water
• so bacteria will feed and respire on the dead plant matter

Question 16

what is the issue with bacteria respiring in the water ?

Answer 16

• it will result in an increase in bacteria
• which are all respiring and using up the oxygen within the water
• lowering the conc of oxygen in the water

Question 17

what will happen if the conc of oxygen in the water is low ?

Answer 17

• fish and other aquatic organisms die
• due to the lack of dissolved oxygen in water