Unit 5: Soil Systems Flashcards
What are the Four Components of Soil?
1) Minerals
2) Organic matter
3) Air
4) Water
How does Soil Interact with the Hydrosphere?
The water cycle moves through the soil by infiltration and water may evaporate from the surface.
How does Soil Interact with the Atmosphere?
The atmosphere may contain particulate matter that is deposited on the soils and particles may blow up into the atmosphere = gaseous emissions/exchange.
How does Soil Interact with the Lithosphere?
Rocks in the lithosphere weather to form soils, and soils at depth and pressure may form rocks (+ leaching and mineral exchange).
How does Soil Interact with the Biosphere?
Plants in the biosphere may extract nutrients from the soils and dead plants may end up forming parts of the soil (decomposition + nutrient exchange).
What are the Roles of Soil?
- Supplies nutrients and water for plant growth
- Water storage and purification system
- Habitat for organisms
- Modifies atmosphere through respiration
What Factors are the Characteristics of Soil Dependent Upon?
- Climate (precipitation/evaporation)
- Organisms (breakdown of organic matter)
- Relief (elevation)
- Parent material (original material soil develops from)
- Time (amount of time it takes to form)
List the Soil Horizons
O – Organic matter + litter layer
A – Surface soil + minerals
E – Leaching occurs
B – Subsoil + organic compounds
C – Parent rock + unbroken rock + soluble compounds
R – Bedrock + parent material + base of soil type
What are the Inputs of a Soil System?
- Organic material
- Precipitation (water)
- Gasses from respiration + atmospheric
- Excretion from plant roots
- Minerals from the breakdown of parent material
What Type of System is Soil?
Dynamic open system.
What are the Outputs of a Soil System?
- Nutrients absorbed plants growing in the soil
- Nutrient loss through leaching
- Loss of soil through erosion
- Evaporation
- Nutrients released by weathering
Give 2 Examples of Transformation in the Soil System
1) Decomposition
2) Weathering
Give 2 Examples of Transfers in the Soil System
1) Absorption
2) Percolation
What is Weathering?
Breakdown and fragmentation of rock into smaller particles.
What is Soil Texture?
The size of the solid particles in a soil.
List the Types of Soil Texture
1) Clay
2) Loam
3) Sand
What Factors does Productivity of Soil depend Upon?
- Mineral content
- Drainage
- Water-holding capacity
- Air spaces
- Biota
- Potential to hold organic matter
What are the Characteristics of Clay?
Mineral content: intermediate Drainage: poor Water-holding capacity: high Air spaces: small Hold organic matter: intermediate Productivity: intermediate
What are the Characteristics of Sand?
Mineral content: high Drainage: very good Water-holding capacity: low Air spaces: large Hold organic matter: low Productivity: low
What are the Characteristics of Loam?
Mineral content: high Drainage: good Water-holding capacity: intermediate Air spaces: intermediate Hold organic matter: high Productivity: high
What Soil Texture is Best for Agriculture?
Loam
Define Food Security
When all people at all times have access to sufficient, safe, nutritious food to maintain a healthy and active life.
State the Different Types of Farming
1) Subsistence
2) Intensive
3) Nomadic
4) Shifting cultivation
5) Commercial
What is Subsistence Farming?
When farmers grow food crops to meet the needs of themselves and their families/locality.
What is Intensive Farming?
Method of farming that uses large amounts of labor and investment (inputs) to increase the yield of the land (outputs).
What is Nomadic Farming?
Form of pastoralism in which livestock are herded in order to seek for fresh pastures on which to graze
What is Shifting Cultivation?
A system of cultivation in which a plot of land is cleared and cultivated for a short period of time, then abandoned and allowed to revert to producing its normal vegetation while the cultivator moves on to another plot.
What is Commercial Farming?
Farming method in which plant and livestock production is practiced with the intention of selling the products on the market.
What Factors Affect the Choice of Farming Method?
- Environmental conditions
- Access to technology
- Available financial funds
- Environmental value systems
- Government and political initiatives
Distinguish between Arable, Pastoral and Mixed Farms
Arable farms will focus on crops such as corn. Pastoral farms focus on rearing animals. Mixed farms produce both.
What are the Ecological Causes for Imbalance in Food Distribution?
- Poor weather and severe weather events
- Soil degradation
- Declining biodiversity
What are the Economic Causes for Imbalance in Food Distribution?
- Demand for cereal grains has outstripped supply
- Rising energy prices and transport costs
- Underinvestment in technology in LEDCs
- Food is exported rather than sold domestically
What are the Socio-Political Causes for Imbalance in Food Distribution?
- Trade protection favors MEDCs
- Inadequate system of food aid
- Disagreements over transboundary resources
Define Malnutrition
Insufficiency in one or more of the nutritional elements necessary for health and well-being.
Distinguish between Food Waste and Food Loss
Food waste occurs when edible foodstuffs are thrown away at the retail and consumer level. Food loss refers to food that spills, spoils (becomes inedible).
Why is Waste Production Lower in LEDCs?
- Less is bought (lower income)
- Less packaging
- Disposable items are used less
- Lower literacy levels = less written material
What is Sustainable Agriculture?
Agricultural systems emphasising biological relationships and natural processes that maintain soil fertility.
Define Food Miles
The distance food travels from the farm where it is produced to the plate of the final consumer.
Give a Real-life Example of Commercial Farming
Canadian prairies:
• Output: wheat grain, waste, straw bales animal feed
• Issues: soil degradation, CO2, use GMOs
Give a Real-life Example of Subsistence Farming
Gange River (India): • Rice in padi field + labor-intensive • Issues: methane, water-intensive
What is the Main Difference between Aquatic and Terrestrial Food Production Systems?
In terrestrial systems food is mainly harvested at low trophic levels (producers/herbivores). In aquatic systems food is mainly harvested at high trophic levels.
How can Food Production be Sustainable?
- Economic support for farmers
- Technology research for sustainable farming
- Using farmers markets
- Growing indigenous crops
- Monitoring multinationals
- Using buffer zones (nutrient run-off)
- Polyculture and crop rotation
- Reduction of meat production
What Characteristics Must Soil Contain in order to be Suitable for Plant Growth?
- Organic matter
- Adequate pH
- Healthy soil community
- Nutrients and minerals
Why is Soil Considered a Non-Renewable Resource?
Because it is not replaceable within a human lifespan or at a pace faster than that at which it is used; for soils to be more sustainable we need to dramatically reduce loss and degradation rates and improve rates of soil formation.
What is Soil Degradation?
The decline in quantity and quality of soil.
What Human Activities Cause Soil Degradation?
- Overgrazing
- Deforestation
- Urbanization
- Unsustainable agriculture (mono or irrigation)
What are the Processes of Soil Degradation?
- Erosion (by wind + water)
- Biological deg. (loss of hummus/plants)
- Physical deg. (loss of structure/permeability)
- Chemical deg. (acidification/salinization/etc)
What is Land Degradation?
The decline in land quality and productivity.
What is Desertification?
The spread of desert-like conditions into previously green areas causing long-term decline in biological productivity.
What are the Impacts of Desertification?
Social: hunger, illness, reduced performance
Economic: reduced yield, falling income
Environmental: reduce nutrients, moisture, organic c.
What are the Causes of Desertification?
- Overcultivation
- Overgrazing
- Deforestation
- Lack of education
List Examples of Soil Conservation Methods
- Afforestation
- Soil conditioners (lime + organic material)
- Wind reduction (shelterbelts, strip cultivation)
- Contour ploughing
- Crop rotation
- Drip irrigation
What Methods can be Used to Prevent Soil Erosion?
- Reduce water flow (terracing, contour ploughing)
- Use roots of crops to help bind the soil
- Reduce the use of heavy machinery
What Methods can be Used to Manage a Salt-Affected Soil?
- Flushing with water to leach the salt away
- Using calcium sulfates to replace sodium ions
- Reduction in evaporation losses
How does Soil Change Throughout Succession?
1) Rock disintegrates with lichen + weathering
2) Parent material forms + small organisms
3) Horizons form + minerals + organic matter
What is Overgrazing and How does it Cause Soil Degradation?
When farmers stock too many animals on their land: they damage the soil surface by eating the vegetation and digging or compacting soil with their hooves.
What is Overcropping and How does it Cause Soil Degradation?
When the land is being continuously under cultivation and is not allowed to replenish; this reduces the soils ability to produce humus becoming drier and less fertile.
How does Monoculture Cause Soil Degradation?
Leads to soil exhaustion and lost nutrients are replaced by the use of fertilizers.
