Themes to talk about Flashcards
1
Q
Boundaries to sustainable management of soils?
A
- Politics - war and pandemics get in the way (ukraine war increased fertiliser prices)
- Implementation costs
- Initial yield loss
- Money - New machinery cost money
- Lower yield rates for organic farming
2
Q
Water Security
A
- Soil filters and stores water
- 2 bn people living in countries facing water stress
- 70% of freshwater use is in agriculture
3
Q
Food Security
A
- Losing arable soil
- 16% has lifespan of less than 100 yrs
- No soils = no food
4
Q
Climate change
A
- Soils lock up carbon
- Carbon stored in soil 4x higher than vegetation or atmosphere
- Feedback Loops
- When carbon is released it adds to global warming - melting cryopshere - losing freshwater - destabilising land (permafrost)
- Increased extreme weather increases soil erosion
5
Q
How does Conventional Agriculture effect soil structure?
A
- Compaction causes loss of pores
Soil can become a hostile or suboptimal environment - Reduced soil functionality - need to add fertiliser etc to make it functional again.
6
Q
Why do farmers till?
A
- To make fields optimal for growing crops
- Long term it has cause soil erosion/degredation
7
Q
Types of tilling techniques
A
- Conventional tilling using multiple forms of machinery, tractors need to pass over soil many times adding to compaction of soil
- Direct drill (no till) best for soil structure - only passes over field once and does not disturb soil too much
- Low-till - minimal disturbance
- Variable/reduced tyre pressure of tractors can reduce soil compaction
8
Q
What are the ecosystem engineers involved in formation of macroaggregates?
A
- Fine roots, especially of grasses
- Mycorrhizal fungi and other fungi
- Earthworms and other soil animals
9
Q
Ecosystem services
A
- Provisioning (fresh water, fuel, food
- Regulating (climate, erosion, and floods),
- Cultural (aesthetic or spiritual values)
- Supporting (physical support to plants, animals and human infrastructure)
10
Q
Cover Crop benefits
A
- Reduce soil erosion
- Can help retain water in soil and aid filtration
- Preserve nutrients for cash crops
- Legumes fix N into soil that would otherwise leach off
- Grass offers soil cover
- Broadleaf - decay quickly and leave nutrients in soil
- Can suppress disease, parasites
- Can increase earthworm density and improve soil structure
- PREVENTS SOIL EROSION
11
Q
Cover crop issues
A
- Results are very variable
- In semi-arid regions cover crops and use lots of water that would otherwise be used for cash crops
- Some environments respond better
12
Q
Soil Erosion
Kopittke, 2019, FAO, 2018
A
- Soil erosion = 10-1000x higher than formation.
- 98.8% of food comes from soil
- Soil degradation costs ~ US$400 billion per year
