Soil Ecosystems, Sustainability, and Environmental Principles
Classified in Geology
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Soil: A Vital Ecosystem
Soil is a complex ecosystem made up of minerals, organic material, gases, and liquids, which forms the habitat for many organisms. As part of the lithosphere, soil stores and transfers heat.
Soil System Components
| Category | Elements/Processes |
|---|---|
| Storages | Organic matter, organisms, nutrients, minerals, air, and water |
| Transfer within the soil | Biological mixing, translocation, and leaching |
| Inputs | Organic material, precipitation, and energy |
| Outputs | Uptake by plants and soil erosion |
| Transformation | Decomposition, weathering, and nutrient cycling |
Soil Particle Size
Particle size order from smallest to largest: Clay < Silt < Sand
Ensuring Soil Sustainability
- Fertile soil is a non-renewable resource.
- It cannot be replaced quickly.
- Practices like crop rotation and the addition of organic matter are crucial for sustainability.
The Soil Food Web
The soil food web involves complex interactions of organisms and nutrients.
- Inputs: Fertilizers, nitrogen fixation, plant and animal residues, precipitation
- Outputs: Crop removal, volatilization, leaching loss, denitrification
Key Agricultural & Economic Terms
LEDC: Low-Income Developing Country
A country with low to moderate industrialization.
MEDC: More Economically Developed Country
A highly industrialized country with a high average Gross National Product (GNP) per capita.
Understanding Agribusiness
The business of agricultural production, including farming, seed supply, food harvesting, distribution, processing, and storage.
Commercial Agriculture Defined
Large-scale production of crops and livestock for sale.
Subsistence Agriculture Explained
Farming for self-sufficiency, growing enough for a family's needs.
Systems and Thermodynamics
Defining a System
A system is a set of interactions; it can be living or non-living.
Types of Systems
- Open: Exchanges both energy and matter.
- Closed: Only exchanges energy.
- Isolated: Energy and matter are not exchanged.
Transfer vs. Transformation
- Transfer: Basic flow through a system; a change in the location of energy or matter.
- Transformation: A new product is created; a change of state.
First Law of Thermodynamics
Energy in an isolated system can be transformed but cannot be created or destroyed.
Second Law of Thermodynamics
Energy is lost in the different levels of a system, often as heat, leading to an increase in entropy.
Understanding Pollution Sources
Point-Source vs. Non-Point Source Pollution
Point-source pollution is easy to identify. As the name suggests, it originates from a single, identifiable place. Non-point source pollution is harder to identify and address, as it comes from diffuse sources over a wide area.