Soil Flashcards
What does soil contain?
- Organic matter
- Mineral matter
- Live/dead matter
- Air
- Water
Is soil important to biodiversity?
Yes, it contains 59% of all biodiversity
How is soil different to sediment?
Soil contains life, and actively proccesses biomatter
Soil Functions
- Plant growth medium
- Nutrient storage
- Chemical filter
- Building material
- Water storage and regulation
- Habitat
- Carbon store
- Cultural heritage
Soil growth rate
0.035mm/year
What causes soil instabilty?
- Overgrazing
- Nutrient mining
- Erosion
- Population issues
- Drought, floods
How many tonnes are lost yearly?
35 thousand million tonnes of soil
What is the current state of sub-saharan soils?
Deficient in organic matter and in key nutrients, caused by intensive farming
Sub-saharan soils have lost
- 22kg of nitrogen
- 2.5kg of phosphorus
- 15kg of potassium
What is the sub-saharan crop yield?
1 tonne per hectacre
Why are fertilizers not used in sub-saharan Africa?
Expensive due to transport
What happened 2005-2009?
Fertilizer use doubled due to a malwain goverment scheme costing $461.4 million
Alternatives to fertiliser use
- Nitrogen-fixing legumes, such as pigeon pea. This can increase yields by 115%. However, it takes up land
- Fertiliser trees which fix nitrogen, improve soil content and reduces transpirtation and evaporation
Paper?
African agriculture: Dirt poor
Natasha Gilbert
