Soil and Food Production Systems

Introduction

• Episode 5 of the series
  • Focuses on soil and food production systems.
  • Applies the systems approach to soil.

What is Soil?

• Soil is a complex ecosystem:
  • Supports plant growth and provides habitat for microorganisms.
  • Holds minerals and nutrients, filters water, and manages heat transfer.
• Soil is a non-renewable resource:
  • Takes a long time to replenish.
  • Difficult to use sustainably.

Earth’s Key Spheres

• Biosphere: Living things.
• Hydrosphere: Water cycle.
• Pedosphere: Soil systems.
• Atmosphere: Air (upcoming topic).
• Lithosphere: Rock cycles (not covered in syllabus).

Soil Systems: Transfers and Transformations

• Transfers (Inputs):
  • Organic and parent material.
  • Precipitation, infiltration of soil layers, energy.
• Outputs:
  • Leaching (minerals and water).
  • Nutrient uptake by plants, mass movement.
• Transformations:
  • Decomposition, weathering, nutrient cycling (carbon and nitrogen).

Soil Profile

• Layers:
  • Bedrock, parent material, subsoil, alluvion/horizon, topsoil.
• Each layer has different characteristics.

Soil Composition

• Four main components:
  • Mineral particles, organic remains (from dead plants), water, air.
• Soil Texture Triangle:
  • Displays percent clay, sand, silt.

Importance of Soil Texture

• Loam: Ideal soil composition.
  • Balance between sand and clay particles.
  • Supports water retention and biota growth.
• Sand:
  • Large particles, good drainage, but low nutrient retention.
• Clay:
  • Small particles, retains water, but limits biota and drainage.

Implications for Primary Productivity

• Productivity depends on mineral content, water drainage, pore spaces, biota presence, and organic matter potential.

Food Production Systems

• Extensive vs. Intensive Farming:
  • Extensive: Low inputs/outputs.
  • Intensive: High inputs/outputs.
• Pastoral vs. Arable:
  • Pastoral: Raising animals on non-arable land.
  • Arable: Growing crops.
• Subsistence vs. Commercial Farming:
  • Subsistence: Just enough for family, polyculture.
  • Commercial: For profit, monoculture.

Food Distribution and Sustainability

• Imbalance in food distribution.
• Cultural factors affect food harvesting and consumption.
• Aquatic Food Production Systems:
  • Food from higher trophic levels, efficient energy conversion in water.
  • Less initial energy intake.

Increasing Sustainability in Food Production

• Strategies:
  • Eat at lower trophic levels.
  • Increase local food consumption.
  • Improve labeling for consumer choices.
  • Monitor and control by national corporations.

Conclusion

• Ends with an invitation to check out the next episode on the atmosphere as a system and more resources.