Agriculture and Environment Soil Science & Land Management 1 — Questions and Answers
Question 1: Which soil horizon is known as the 'topsoil' and is most critical for crop production?
- O horizon
- A horizon (Correct answer)
- B horizon
- C horizon
Correct answer: A horizon
The A horizon (topsoil) contains the highest concentration of organic matter and nutrients, making it most important for plant growth.
Question 2: What is the primary cause of sheet erosion in agricultural fields?
- Wind movement
- Raindrop impact and surface runoff (Correct answer)
- Freeze-thaw cycles
- Tillage operations
Correct answer: Raindrop impact and surface runoff
Sheet erosion is caused by raindrop impact dislodging soil particles combined with thin, uniform surface runoff carrying them away.
Question 3: Which tillage practice best reduces soil erosion by leaving crop residue on the surface?
- Moldboard plowing
- Subsoiling
- No-till or conservation tillage (Correct answer)
- Deep ripping
Correct answer: No-till or conservation tillage
No-till and conservation tillage practices leave crop residues on the soil surface, protecting it from erosion and improving water infiltration.
Question 4: What does a soil pH of 6.5 indicate?
- Strongly acidic soil
- Slightly acidic to neutral soil (Correct answer)
- Strongly alkaline soil
- Highly saline soil
Correct answer: Slightly acidic to neutral soil
A pH of 6.5 is slightly acidic to near-neutral, which is optimal for most crops as it maximizes nutrient availability.
Question 5: What is the primary benefit of cover crops in US agricultural land management?
- Increasing soil salinity
- Preventing soil erosion and improving organic matter (Correct answer)
- Reducing soil moisture retention
- Eliminating beneficial insects
Correct answer: Preventing soil erosion and improving organic matter
Cover crops protect soil from erosion, add organic matter when tilled under, and improve soil structure and fertility.
Question 6: Which USDA classification describes soil with roughly equal parts sand, silt, and clay?
- Sandy loam
- Clay loam
- Loam (Correct answer)
- Silty clay
Correct answer: Loam
Loam contains balanced proportions of sand, silt, and clay, making it one of the most productive soil textures for agriculture.
Agriculture and Environment Soil Science & Land Management 1
Which soil horizon is known as the 'topsoil' and is most critical for crop production?