5B Fertilisers and Eutrophication Flashcards
1
Q
What are artificial fertilisers
A
inorganic
they contain pure substances as powders or pellets
1
Q
How are nutrients lost through harvesting
A
- Crops take in minerals as they grow and use them to build their own tissues
- When crops are harvested they are removed from the field where they are grown rather than being left to die and decompose , so the mineral ions are not returned to the soil by decomposers in the nitrogen or phosphorus cycles
- Phosphates and nitrates are also lost from the system when animal or animal products are removed from the land . Animals eat grass and other plants, taking in their nutrients . When they are taken elsewhere for slaughter or transferred to a different field . the nutrients are replaced through their remains or waste
2
Q
What are natural fertilisers
A
organic matter, manure composted vegetables, crop residues and sewage sludge
3
Q
Environmental issues that are raised when using fertilisers
A
- Sometimes too much fertiliser is added
- This can lead to the fertilisers leaching into waterways
- This can lead to eutrophication
- Leaching is more likely to occur if fertiliser is added just before heavy rainfall
- Leaching is less likely in natural fertilisers
- The leaching of phosphates is less likely than the leaching of nitrates because phosphates are less soluble in water
- Using fertilisers changes the balance of nutrients too much can cause plants and crops to die
4
Q
Describe the process of eutrophication
A
- Mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds and rivers
- Large amounts of algae block light from reaching the plants below
- Eventually the plants die because they are unable to photosynthesise enough
- Bacteria feed on the dead plant matter. The increased number of bacteria reduce the oxygen concentration in the water by carrying out aerobic respiration
- Fish and other aquatic organisms die because their isn’t enough dissolved oxygen
