Soil Components
What are the four main components of soil?
Mineral particles, organic matter, water, and air
What is soil?
A mixture of mineral particles, organic matter, water, and air
What is a soil horizon?
A layer of soil
A student finds dead leaves breaking down on the ground. What process is occurring?
Decomposition
Is soil the same thing as solid rock? Explain briefly.
No. Soil contains mineral particles, organic matter, water, and air.
What is the name for the tiny pieces of rock and minerals found in soil?
Mineral particles
What process breaks rocks into smaller pieces?
Weathering
Which soil layer contains much of the organic material and humus?
The O horizon
A rock breaks into smaller pieces because of wind and rain. What process is occurring?
Weathering
Name one way soil helps plants.
It provides nutrients, water, and support for roots.
What is humus, and how does it form?
Humus is decayed organic material formed as dead organisms and waste decompose.
What is decomposition?
The breakdown of dead organisms and other organic material
Which soil layer is called topsoil?
The A horizon
A soil sample contains many decayed leaves and other organic materials. Which soil component is abundant?
Organic matter
Name two living organisms that can live in soil.
Examples include earthworms, ants, fungi, and bacteria.
Which soil component fills spaces between particles and helps plants survive?
Water
How do weathering and decomposition work together to form soil?
Weathering breaks rocks into smaller particles, while decomposition adds organic material.
Which soil layer contains accumulated minerals washed down from above?
The B horizon, or subsoil
A plant's roots grow into the upper soil layer where many nutrients are found. Which horizon is the plant growing in?
The A horizon
How can removing plants from an area increase soil erosion?
Plant roots hold soil in place, so removing plants leaves soil more exposed to erosion.
Why is air important in soil?
Soil air provides oxygen for plant roots and soil organisms.
Why does soil formation take a long time?
Rocks weather slowly, and organic matter takes time to accumulate and decompose.
Which soil layer is made mostly of partially weathered parent material?
The C horizon
Water carries dissolved minerals from upper soil into a lower layer. What soil process does this describe?
Erosion
A farmer notices that soil washes away during heavy rain. Name one way to reduce soil erosion.
Plant vegetation, use mulch, or plant cover crops.