EN: Fertilisers and Eutrophication Flashcards
How does harvesting crops affect the nutrients in the soil?
- Mineral ions found in plants are not returned to soil by decomposers in nitrogen or phosphorus cycles.
What happens to nutrients when animals or animal products are removed from the land?
- Phosphates and nitrates are lost.
- Animals eat grass and plants, taking in nutirnets.
- When they are move, the nutrients aren’t replace through their remains or waste products.
What does the addition of a fertiliser do the soil?
Replaces lost minerals, so more energy from the ecosystem can be used for growth, increasing the efficiancy of the energy transfer.
What are the two types of fertilisers?
Artificial
Natural
Artificial fertilisers
Inorganic - contain pure chemicals as powders or pellets.
Natural fertilisers
Organic matter - include manure, composted vegetables, crop residues and sewage sludge.
What environmental issues arise from the use of fertilisers?
- Leaching into waterways.
- Can result in eutrophication.
Leaching
Water-soluble compounds in the soil are washed away, often into nearby ponds and rivers.
Is leaching more likely with natural or artificial fertilisers?
Why?
Artificial.
- Inorganic ions are relatively soluble - excess minerals not used immediately are more likely to leach into waterways.*
- Whereas, in natural fertilisers, the release of nitrogen and phosphorus is more controlled.*
When is leaching likely to occur?
If the fertiliser has been applied just before heavy rain.
What is eutrophication caused by?
Excess nutrients
Describe the process of eutrophication:
- Mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds and rivers.
- Large amounts of algae block light from reaching plants below.
- Plants can’t photosynthesise and so die.
- Bacteria feed on dead plant matter and population increases.
- Reduces oxygen concentration in water by carrying out aerobic respiration.
- Fish and other aquatic organisms die because there isn’t enough dissolved oxygen.
