WEEK 13 - Soil x Nutrients Flashcards
What is soil?
A mixture of mineral and organic matter, water, and air.
Supports plant growth.
What does soil come from?
It is part of the regolith, which consists of rock and mineral fragments produced by weathering.
What are the typical components in soil for good plant growth?
- Mineral matter
- Organic matter
How does mineral matter help plants?
Provides inorganic nutrients for growth
Gives soil structure and supports root growth
How does organic matter benefit soil?
Acts as a nutrient source
Replenishes nutrients taken out by plants
What is the role of water in soil for plant growth?
Water transports nutrients and air to plant roots
Why is air important in soil?
Taken up by plant roots
Supports decomposers that break down organic matter
What is parent material in soil formation?
Source of soil’s mineral content
Residual soil: from bedrock below
Transported soil: from material deposited elsewhere (e.g., glacial sediment in southern Ontario)
How does time affect soil formation?
More time = more developed soil
Soil formation rate depends on climate and geologic conditions
Why is climate important for soil formation?
Most important factor
Temperature and precipitation control weathering and organic activity
How do plants and animals affect soil?
Change soil’s physical and chemical properties
Add organic matter
What role does slope play in soil development?
Steep slopes = thin or poorly developed soil
Best soils form on flat or gently rolling land
What is a soil profile and how does it form?
Soil forms from the surface downward
Top: organic matter (from plants/animals)
Middle (subsoil): forms between top and bottom layers
Bottom: weathered parent material
Layers are called soil horizons
What are the main layers in an ideal soil profile?
- O-horizon: loose, partly decayed organic matter (humus)
- A-horizon: mix of humus + mineral matter
- E-horizon (not always present): leaching zone (stuff removed by water)
What are the deeper layers in a soil profile?
- B-horizon (subsoil): where clays and ions from above build up
- C-horizon (soil base): partly altered parent material (rock or sediment)
O-horizon
rich in organic matter (humus)
A-horizon
mix of minerals and humus
B-horizon
called subsoil, rich in iron and clay
C-horizon
made of weathered parent material (rock or sediment)
What is soil texture and why does it matter?
Based on grain size of mineral matter
Affects water retention, nutrients, and ease of farming
What are the pros and cons of clay-rich soil?
Pros: Holds water and nutrients well
Cons: Sticky when wet, hard when dry, tough on farming equipment
What are the pros and cons of sand- or gravel-rich soil?
Pros: Drains water quickly
Cons: Loses nutrients fast, easily eroded, poor cohesion
What is loam and why is it ideal for crops?
Mix of clay, silt, and sand
Good water + nutrient retention
Allows for proper drainage
A “happy medium” soil type
What are examples of crop preferences for loam?
Different crops like different loam mixes
Potatoes prefer sandy loam → loose enough for tubers to grow
