Unit 5: soil systems, terrestrial food production systems, and societies

Soil profile

A vertical section of soil divided into layers (horizons) according to physical & chemical characteristics

The 5 layers of soil profile

• O (humus on organic) →undecomposed litter

• A (topsoil) = mixed mineral - organic

• E (eluviated horizon)

• B (subsoil / illuvial horizon)

• C (parent material)

• R (bedrock)

Why is soil important?

• Most good stuff tar humans is grown in soil

• Provides nutrients for producers

• Habitat for many organisms

• Filters & stores water

• Part of nutrient cycle

• Provides raw materials - peat, sand, day, etc.

Soil storages

Include;

• organic matter

• Organisms

• Nutrients

• Minerals

• Air and water

Soil flows:

Include;

• precipitation

• Irrigation

• Infiltration

• Overland & groundwater flow

• Evaporation

• Ploughing /aerating

• Flooding

• Draining

• Weathering

• Leaching

• Decomposition

• Mixing

• Erosion

Soil forming

Soil is considered a non-renewable resources due to the long time it takes to develop -succession

Processes involve;

• Gains & losses of material to and from the profile

• Movement of water between the horizons

• Chemical transformations with each horizon

Chemical transformations of soil-forming

1. Decomposition → changes leaf litter into humus - overtime humus decomposes due to mineralisation, releasing nitrogenous compounds

2. Weathering

3. Biological mixing & nutrient cycling

4. Translocation & leaching → water dissolves materials & carries it downwards (mostly)

5. Deposition of materials →organic & inorganic

Sail structures →3 particles

• Sand (largest) → falls apart easily

• Slit → feels slippery & holds together

• Clay (smallest) → feels thick & sticky & can form into shapes

Soil texture

The shape and arrangement of individual sail particles

→ is determined by the proportion of the particles present in the soil

Loam

The well-balanced soil with fairly equal portions of each particle.

→ ideal for cultivation (= growing plants)

Soil porosity

The amount of space between each soil particle

Greater porosity = greater water retention

Soil permeability

The ability of air and water to flow from upper layers to lower layers.

Large pore space = faster vale of drainage

The surface area of soil

Determines the amount of water and minerals that can be retained against the force of gravity.

Smaller particles = higher surface area to volume ratio = more water & nutrients retained.

Workability

How much force it takes to pull a slough through the soil. Soils with more clay are more difficult to work/plough

→ soils are ranked light (easy), medium, or heavy (difficult)

Primary productivity of soil depends on:

• Mineral content

• Air space (porosity)

• Drainage (permeability)

• Water-holding capacity

• Biota (organic material)

• Potential to hold organic material

Causes of unsustainable food production

• Increase in world population

• A shift in diet (away from grains, towards animal products)

• Increase in human urbanisation (limiting available arable land)

• Degradation of soil

Sustainable good production is influenced by:

• Scale

• Mechanisation

• Fossil fuel use

• Seed / crop / livestock choice → native on not

• Water use

• Fertilisers

• Pest control

• Pollinators

• Antibiotics

• Legislation

• Levels of commercial vs substances food production

Inequalities in Global food Supply

Exist in food production and distribution around the world

• ¾ of the human population does not get enough food

• 1/6 of the population is going hungry

• People in LEDCs make up the majority of those people

• MEDCs have a surplus of food

Subsidizing

Farmers are paid to let their feed vest

Import tariffs

Makes it harder for LEDCs to sell their food

Export subsidies

Provided by MEDCs to their farmers make farm products from LEDCs uncompetitive

Differing reasons for good waste between MEDCs and LEDCs

LEDCs;

• Poor agricultural practices → choosing the wrong thing to grow

• Inadequate roadway/railways to transport food

• Poor storage facilities

MEDCs;

• Sell-by dates at supermarkets

• Buy - one - get-one free promotions at supermarkets

• Western demand for perfect looking lead

Influences over food production

• Cultural significance

• Economic factors

• Ecological factors

Shifting cultivation

Slash and Burn → an example of extensive subsistence farming. Worked well when population density was low

Commercial farming

Farming to sell

Subsistence farming

Farming to survive

Intensive farming

Farming to compact- many things in a small area

Extensive farming

Farming in a Lange area

Efficiency of food production

We get a lot more from producers than consumers but we need different demands from each

Models

• Farm inputs→ machinery, tractors, cows, seeds, slurry, fertilisers

• Farm processes → milking cows, spreading slurry, feed animals, ploughing

• Farm outputs → beef, pork, milk, eggs, profits

Environmental impacts of feel production systems

• Soil degradation from erosion

• Desertification

• Eutrophication

• Pollution from pesticide, and fertilisers

• Salination from over-irrigation

• Lowered water tables

• Loss of valuable habitats

• Disease epidemic from increasing density

Ways to increase sustainability

• Reduce meat consumption

• Increase consumption of seasonal & locally grown products

• Increase consumption of sustainably grown products

• Plant buffer zones

• Improve accuracy of food labels

• Improve standards and practices for food production → which is monitored & controlled by governments

Soil degradation

Change through succession. Fertile soil contains a community of organisms that work to maintain functioning nutrient cycles and are resistant to sail erosion

Reduction of soil fertility due to human interaction

• Deforestation

• Intensive grazing

• Urbanisation

• Irrigation → when there is too much

• Monoculture

• Commercial food production

Results of reduced fertility

• Soil erosion

• Toxification

• salination

• Desertification

Soil conservation

To limit/ prevent erosion;

• Reduce water & wind erosion → physical barriers, contour ploughing, cover crops, minimise tillage/ploughing, mixed cropping

• Nutrient management → crop rotation/animal rotation, crop selection (plant native crops), soil conditions/chemicals, mulching, reduce evaporation