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Flip to reveal answersWhat are the main components of healthy soil (approximate proportions)?
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All 10 Flashcards — Soil formation and composition
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Question
What are the main components of healthy soil (approximate proportions)?
Answer
About 45% minerals (sand/silt/clay), 25% air, 25% water, 5% organic matter (humus and organisms).
💡 Hint
Think: minerals, air, water, organic matter.
Question
Soil forms from which two main inputs/processes?
Answer
Weathering of rock plus the addition of organic matter over time (humus formation).
💡 Hint
Rock + organic matter.
Question
Define weathering in the context of soil formation.
Answer
Weathering is the breakdown of parent rock into smaller particles by physical, chemical, or biological processes.
💡 Hint
Rock → particles.
Question
List the three types of weathering.
Answer
Physical weathering, chemical weathering, biological weathering.
💡 Hint
Three categories.
Question
Name the three main types of weathering and give one example of each.
Answer
Physical: freeze–thaw or temperature changes; Chemical: dissolution or oxidation; Biological: roots or burrowing organisms breaking rock.
💡 Hint
Physical / chemical / biological.
Question
Which CLORPT factor refers to slope and drainage?
Answer
Relief (topography).
💡 Hint
R = relief.
Question
What part of soil composition is usually ~5% but crucial for fertility?
Answer
Organic matter (humus and soil organisms).
💡 Hint
Small % but high impact.
Question
What does CLORPT stand for in soil formation?
Answer
Climate, Organisms, Relief (topography), Parent material, Time.
💡 Hint
Mnemonic for soil-forming factors.
Question
Why is soil considered effectively non-renewable on human timescales?
Answer
Because soil forms extremely slowly (around 1 cm per 100–1000 years), so lost topsoil cannot be replaced within human lifetimes.
💡 Hint
Rate of formation is very slow.
Question
Exam-style point: how should you describe soil as a resource?
Answer
Soil is technically renewable, but the renewal rate is so slow that degraded soil is effectively non-renewable on human timescales.
💡 Hint
Renewable vs timescale.
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Full study notes for Soil formation and composition
Topic 5.1 hub
Soil systems
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