Ch 5: Soil Systems and Societies

Ch 5 - Soil Systems and Society

Processes:
1. Transfers: of materials within the soil including biological mixing, leaching, contribute to the organisations of the soil. (horizons) (leaching and evaporation)
2. Transformation: The complete change of materials in the soil(decomposition, weathering, nutrient cycling)
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Soil Horizons: (O,A,B,C) and sometimes E:
- O: organic, leaf litter, comes from organisms that die and end up on top of the soil. Fungi, bacteria, and animals will decompose dead materials
- A: mineral layer, topsoil, upper layer, where humus builds up. Humus is formed when partially decomposed organic matter is mixed with fine material particles, when decomposition is incomplete, a layer dark organic matter is formed → humus layer
- E: leached horizon
- B: subsoil, where soluble minerals and organic matter are deposited from the layer above. For example: clay, iron salts are deposited
- C: parent material, bedrock or another medium

Soil structure and texture:
- Ideal soil: loam which is the balance between clay and soil. Is known for its porosity and permeability, water holding ability, aeration, proportion of materials (sand, silt, clay)
- Pore spaces determine water drainage
- Surface area determines water and nutrients retained
- Light, medium, heavy
- Soil texture triangle: illustrates the differences in composition of soils
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Horizons:
1. Top layers → rich in organic material
2. Bottom layers → consist of inorganic material (derived of weathering of rocks, within this, translocation takes place)

Translocation: process in which materials stored and layers are formed by water carrying particles either up or down
- Also occurs in irrigation and in warmer climates where precipitation < evaporation

Leaching: occur when water flows down in the soil, dissolving minerals and transporting them downwards
- Happens in cooler climates when precipitation > evaporation

Loam soils are ideal for agriculture, as they are a mixture of sand, clay, and silt
- Sand particles: ensure good drainage and a good air supply to the roots
- Silt particles: help hold sand and clay particles and can be worked easily
- Clay: retains water and supplies nutrients (fertile)

Porosity: amount of spaces between particles
Permeability: the ease at which gases and liquids pass through the soil
Acidification of soil: acid rain causing pollution, adversely affecting soil and causing damage to evergreen forestry
- Fertile soil = non-renewable resource
- Nitrates for leaf and stem
- Phosphates: root system
- Potassium: flower head/fruit
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LEDC’s: less economically developed countries
- Country with low to moderate industrialisation and low to moderate average GNP per capita
MEDC: more economically developed countries
- Highly industrialised country with high average GNP per capita
Agribusiness: business of agriculture production
- Includes farking, seed supply, breeding, machinery, and food harvesting
Commercial agriculture: large scale production of crops and livestock for sale
Subsistence agriculture (or farming): farming or self sufficing to grow enough for a family
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Our food choices are determined by:
- Climate, ecological conditions: adapt through irrigation/greenhouses
- Cultural and religious reasons
- Political reasons: determined by governments to manipulate production
- Socio-economic reasons: market forces determine supply and demand in a free market economy
Livestock: useful means of converting plant material
Harvesting: requires the removal of biomass from the field, net loss of biomass, nutrients, minerals. Crop rotation addresses loss of soil fertility

Factors which cause a decrease in agricultural land: soil erosion, salinisation, desertification, urbination
How to increase sustainability of food supplies:
- Maximising yield: improving tech
- Reduce food storage: improve storage → LEDC: waste of production and storage. MEDC → consumption (applying stricter standards in supermarkets)
- Monitoring and control: regulate imports and exports to reduce unsustainable agricultural practices
- Diet and food: reduce meat, different crops, more protein
- Reduce food processing: decrease use of transport and packaging → overall decrease in energy use
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Processes:
1. Erosion is a process which takes away the soil. Occurs when there is no vegetation in the soil
2. Making soil less sustainable for use:
- Chemicals entering soil → renders soil useless (long term)
- Human activities, overgrazing, deforestation, unsustainable agriculture

Overgrazing: too many animals graze in the same area, leaves bare patches (roots done hold soil together
Overcropping: depletes soil nutrients and makes soil dry (risk of erosion), reduced soil fertility
Deforestation: removal of forests, removal of vegetation leads to erosion
Unsustainable agricultural techniques: cannot be applied long term, removal of crops after harvest (erosion), ploughing in direction of the slope, excessive use of pesticide, irrigation → can cause salinisation as minerals
Monocropping: nutrients are depleted and soil loses fertility
Urbanisation: increasing number of people that live in urban areas, potential land for agricultural land for agriculture has cities built on it

Soil erosion
1. Soil conditions: chalk, crushed limestone, counters soil acidification, lime
2. Wind reduction: plant trees/bushes between fields
3. Soil conserving cultivation techniques: terracing, ploughing, counter farming
4. Improve irrigation techniques

Note

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