soil
Q: What are the main soil horizons and what do they represent?
O: Organic matter (leaves, decomposed plants)
A: Topsoil, rich in organic material and minerals
B: Subsoil, accumulation of minerals leached from A
C: Weathered parent material, little biological activity
Q: What is the rock cycle?
A: A continuous process where rocks change between igneous, sedimentary, and metamorphic types through weathering, erosion, heat, and pressure.
Q: What is mechanical vs. chemical weathering?
A:
Mechanical: Physical breakdown of rocks (e.g., freezing, wind)
Chemical: Chemical changes that break down rocks (e.g., acid rain, oxidation)
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Q: What are the three main soil textures?
A: Sand, silt, clay
Q: How does porosity or permeability affect soil?
A:
Porosity: Amount of pore space → affects water and air storage
Permeability: Ability of soil to transmit water → affects drainage
Q: What is organic matter and why is it beneficial?
A: Decomposed plant and animal material that improves soil structure, fertility, and water retention.
Q: What are the primary nutrients for plants?
A: Nitrogen (N), Phosphorus (P), Potassium (K)
Q: What are secondary nutrients?
A: Calcium (Ca), Magnesium (Mg), Sulfur (S)
Q: What are micronutrients?
A: Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Boron (B), Molybdenum (Mo)
Q: Why is soil pH important?
A: It affects nutrient availability; some nutrients become locked in very acidic or alkaline soils.
Q: Why is nitrogen needed for plants?
A: Nitrogen is essential for chlorophyll production in chloroplasts, which is needed for photosynthesis.
Q: What are the trophic levels in soil?
A:
Producers: Plants, algae
Primary consumers: Earthworms, nematodes, insects
Secondary consumers: Predatory insects, fungi
Decomposers: Bacteria, fungi
Q: What does compost supply to soil?**
A: Organic matter
Microbial diversity
Q: What is humus and how is it created?**
A: Dark, nutrient-rich organic matter formed from decomposed plant and animal material in compost.
Q: What are the main causes of soil erosion?**
A:
Wind
Water
Agriculture and construction
Q: How is irrigation water different from rainwater?**
A: Irrigation water often contains dissolved salts, while rainwater is naturally low in salts.
Q: What are the major cations involved in salinization?**
A: Sodium (Na⁺), Calcium (Ca²⁺), Magnesium (Mg²⁺), Potassium (K⁺)
Q: What is desertification?**
A: Degradation of fertile land into desert, often due to overgrazing, deforestation, or poor irrigation.
Q: What are the pros and cons of different irrigation methods?**
Flood: Easy, cheap; wastes water, can cause salinization
Furrow: Moderate efficiency; labor-intensive
Sprinkle: Even water distribution; can be costly, wind affects efficiency
Drip: Very water-efficient; expensive installation
Q: What is soil carbon sequestration?**
A: The process of capturing carbon dioxide from the atmosphere and storing it in soil as organic carbon.
Q: How can it be increased?**
A: Adding compost or cover crops
Reduced tillage
Agroforestry or planting trees
Crop rotation