chapter 5 notes/flashcards

What are the main components of soil?

Mineral particles, nutrients, organic material, water, air, and living organisms.

List four ecosystem services provided by soil.

Nutrient cycling, water filtration, habitat, and carbon storage.

Describe the O horizon in a soil profile.

Organic matter; layer of relatively undecomposed plant residues.

What is the A horizon also known as, and what occurs there?

Known as topsoil, it's a layer of mineral soil with a greater accumulation of organic matter and soil life. This layer leaches iron, clay, calcium, and organic compounds.

Define eluviation and illuviation.

Eluviation is the movement of dissolved or suspended materials from upper to lower layers; Illuviation is the deposition of eluviated materials in lower soil layers.

What are the inputs and outputs of soil as a system?

Inputs: Weathering, atmospheric inputs, biological nitrogen fixation, precipitation, and plant/animal residues. Outputs: Erosion, leaching, gas losses, evaporation, and crop harvest.

Why is soil considered an open system?

Because it exchanges matter and energy with its surroundings.

List the three main types of soil particles and their characteristics.

Sand: 0.05 mm - 2 mm particle diameter, fast-draining, low nutrient retention. Silt: 0.002 mm-0.05 mm particle diameter, medium water retention and drainage. Clay: <0.002 mm particle diameter, sticky, high water retention, poor drainage.

What is loam, and why is it good for agriculture?

Loam is a balanced mix of sand, silt, and clay, providing good drainage, aeration, and nutrient-holding capacity.

Explain the relationship between porosity and permeability in clay and sand soils.

Clay has high porosity and low permeability, while sand has low porosity and high permeability.

How do clay soils encourage acidity?

High cation exchange capacity holds hydrogen and aluminum, poor drainage leads to organic acid buildup, and leaching removes base cations.

Name three macronutrients essential for plant growth and their roles.

Nitrogen (N): Growth. Phosphorus (P): Roots and ATP. Potassium (K): Water balance.

Differentiate between subsistence and commercial agriculture.

Subsistence agriculture is small-scale and for self-sufficiency, while commercial agriculture is large-scale and for profit.

What is intensive agriculture?

High input/output on a small land area.

Define monoculture and its impact on soil.

Monoculture is growing a single crop, leading to soil degradation.

How do climate, culture/religion, politics, and socio-economics influence food production systems?

Climate determines suitable crops/livestock. Culture/Religion influences diet choices. Politics involves subsidies and regulations. Socio-economics relates to access to land, technology, and labor.

Why is farming lower trophic levels more efficient?

Lower trophic levels (plants) require less energy and resources compared to higher trophic levels (meat).

Where does food waste primarily occur in LEDCs and MEDCs?

LEDCs: poor storage and transport; MEDCs: consumer behavior and overproduction.

List four factors contributing to decreasing land availability per capita.

Urbanization, deforestation, soil degradation, and population growth.

How does soil form through succession?

Weathering breaks down rock, organic matter accumulates, and microorganisms/plants establish, enriching the soil.

Describe three human activities that cause soil degradation.

Overgrazing: Removes vegetation, increases erosion. Overcropping: Depletes nutrients, reduces fertility. Deforestation: Removes root structures, increasing erosion.

How do pesticides and irrigation contribute to soil degradation?

Pesticides kill beneficial organisms; Irrigation leads to salinization.

What is salinization?

The process of excessive accumulation of salts in the soil, often caused by the evaporation of stagnant water used for irrigation.

Explain three processes of soil erosion.

Water Erosion: Runoff removes topsoil. Wind Erosion: Wind blows away loose soil. Tillage Erosion: Plowing disturbs soil, making it vulnerable.

List four soil conservation methods.

Soil conditioners, wind reduction techniques, irrigation management, cover crops, terracing, contour farming, crop rotation.

How do soil conditioners improve soil quality?

They correct deficiencies in structure or nutrients.

How do terraces and contour farming prevent soil erosion?

Terraces prevent water erosion by creating level platforms; Contour farming involves plowing and planting crops at a right angle to the slope.