IB Environmental Systems and Societies SL: Topic 5 - Soil Systems and Society

5.1 Introduction to Soil Systems

Importance of Soil

• Essential for all food production.
• Habitat for organisms.
• Filters water and affects atmospheric temperature and moisture.
• Part of the lithosphere, where life processes occur.

Soil as a System

• Storages: Organic matter, organisms, nutrients, minerals, air, water.
• Transfers: Biological mixing, translocation, leaching, soil erosion, infiltration, percolation.
• Transformations: Decomposition, nitrification, salinization, weathering, denitrification, respiration, photosynthesis.
• Inputs: Organic matter, inorganic matter, precipitation, air, pollutants, energy, fertilizers.
• Outputs: Oxygen, nitrogen, heat, nutrient uptake by plants, soil erosion.

Composition of Soil

• Mineral particles, organic remains, water, and air.
• Rock particles form the soil's skeleton; they can be insoluble or soluble.
• Humus contributes to soil’s dark color and nutrient retention.
• Water movement affects leaching and salinization.
• Soil organisms aid in breakdown and aeration.

Soil Profile

• A vertical succession revealing distinct layers:
  • O Horizon: Organic material on the surface.
  • A Horizon: Upper layer with humus.
  • B Horizon: Deposit of soluble minerals and organic matter.
  • C Horizon: Weathered rock.
  • R Horizon: Parent rock.

Soil Formation

• Interaction of lithosphere, biosphere, atmosphere, and hydrosphere.
• Lithosphere contributes minerals through weathering.

Soil Textures

• Sandy, clayey, and loamy soil types.
• Loam is ideal for farming due to balanced proportions.

5.2 Terrestrial Food Production Systems and Food Choices

Agribusiness

• Involves farming, machinery, chemical use, distribution.

Farming Types

• Commercial farming: Large-scale, high inputs, significant environmental impacts.
• Subsistence farming: Small-scale, labor-intensive, locally sustainable.

Food Production Systems

• Compare extensive vs. intensive farming.
• Impact of livestock/crop choices.

Food Wastage

• MEDCs: Over-purchase, large packaging, subpar produce disposal.
• LEDCs: Poor storage, transportation issues, low-quality disposal.

Determining Food Choices

• Influences include climate, culture, politics, socio-economic factors.

Comparing Food Production Systems

• Need to evaluate inputs, outputs, system characteristics, environmental impacts, socio-economic factors.

Terrestrial vs. Aquatic Systems

• Terrestrial systems use lower trophic levels efficiently.

Increasing Sustainability

• Techniques include improving technology, altering crops, reducing waste, and changing consumption attitudes.

5.3 Soil Degradation and Conservation

Processes Leading to Soil Degradation

• Overgrazing, over-cropping, deforestation, unsustainable practices.

Soil Erosion Processes

• Sheet wash, gullying, wind erosion.

Soil Conservation Measures

• Adding soil conditioners, wind reduction strategies, soil-conserving cultivation techniques, improved irrigation, stopping marginal land ploughing, crop rotation.