4 - Renewable resources Flashcards
What are renewable resources
Can be replenished over short periods of time:
- sunlight, wind, organic matter, soil, groundwater
What is renewable?
- capable of regeneration after harvest
- to be truly renewable, must be harvested at a rate less than or equal to regeneration
- cab be sustainably harvested
How much freshwater is available to us?
0.024% of water supply
97.5% of water is saltwater
Two categories of fresh water
- surface water: lakes, ponds, streams, rivers
- groundwater: underground reservoirs that accumulate in so-called aquifers
Renewable vs non-renewable water
Groundwater (surface water) = renewable
Aquifers = non-renewable
What determines water scarcity? What is physical water scarcity?
Determined by amount and quality of water
More than 75% of river flows are withdrawn for agriculture, industry and domestic purposes - approaching or exceeding sustainable limits
Reasons for water scarcity
Physical shortage, institutional failures or lack of adequate infrastructure to ensure regular supply
Causes of water scarcity
- irrigation (crops with high water demand e.g. corn)
- hydroelectric dams (producing electricity/energy using water)
- bad planning (e.g. las vegas; in middle of desert, one water supply (river delta))
- too many people (esp in dry places)
Agriculture impact on water scarcity
- 70% of all freshwater on the planet is used for growing food
- cotton, rice, sugarcane and wheat = 58% of irrigated farmland
Slide 23
Reducing water footprint
Roles of soil
- fertility (nutrient content) cycles
- organic matter cycles
Problems with soil resource
- erosion (loss of nutrients)
- nutrient and organic matter cycles are unbalanced
- it is drying up (tied to water usage)
- it is getting salty
What is erosion?
Process of removal and transport of the topsoil by action of water, wind and mass movement that causes its deterioration in time
Causes of erosion
- over-cultivation (reusing soil over and over without giving it time to recover)
- over-grazing (remove grass/plants = loss of stability)
- poor forestry practices
- mining
Best practices for good nutrient and organic matter cycling in soil
- cycle fields + fallow years
- plant cover cropping
- leaving crop residuals (dead plants/crops can resupply lost nutrients)
- no till farming
- crop rotation (diff types of nutrients available to soil)