Soil Formation & Erosion

Question 1

When are soils formed?

Answer 1

When parent material is weathered, transported, and deposited.

Question 2

How are soils generally categorized?

Answer 2

By horizons based on their composition and organic material.

Question 3

What can soils be eroded by?

Answer 3

Winds or water

Question 4

How does protecting soils lead to protecting water quality?

Answer 4

Soils effectively filter and clean water that moves through them

Question 5

Protecting soils leads to protecting:

Answer 5

water quality

Question 6

What is soil?

Answer 6

A mix of geological and organic components such as sand, stilt, clay, humus, nutrients, water, air, and living organisms.

Question 7

What is humus?

Answer 7

The main organic part of soil; it’s broken down biomass like leaves, dead animals, waste, etc.

Question 8

What nutrients is found in soil?

Answer 8

Ammonium, phosphates, and nitrates

Question 9

How does soil support plants?

Answer 9

It anchors the roots of plants and provides water, shelter, and nutrients (N, P, K, Mg) for growth.

Question 10

How does soil support water?

Answer 10

It filters rainwater and runoff by trapping pollutants in pore spaces and plant roots. Clean water enters groundwater and aquifers.

Question 11

How does soil support nutrient cycling?

Answer 11

Soil is home to decomposers that break down dead organic matter and return nutrients to the soil.

Question 12

How does soil support habitat?

Answer 12

Soil provides habitat for organisms like earthworms, fungi, bacteria, moles, and slugs.

Question 13

What is weathering?

Answer 13

The breakdown of rocks into smaller pieces.

Question 14

How does weathering occur?

Answer 14

Physically through wind, rain, and the freezing/thawing of ice, as well as biologically through the roots of trees cracking rocks, and chemically through acid rain and the acids from moss/lichen.

Question 15

Weathering leads to:

Answer 15

soil formation

Question 16

How does the weathering of rocks lead to soil formation?

Answer 16

Rocks are broken into smaller and smaller pieces then carried away and deposited by erosion.

Question 17

What is erosion?

Answer 17

The transport of weathered rock fragments by wind and rain. They are carried to a new location and deposited (deposition).

Question 18

How is soil formed from below?

Answer 18

The weathering of parent material produces smaller and smaller fragments that make up geological/inorganic parts of soil such as sand, stilt, clay, and minerals.

Question 19

How is soil formed from above?

Answer 19

The breakdown of organic matter adds humus to the soil, and erosion deposits soil particles from other areas further adding to the soil.

Question 20

How does parent material affect soil formation?

Answer 20

Parent material dictates the soil pH and nutrient content.

Question 21

How does topography affect the formation of soil?

Answer 21

Steep slopes lead to too much erosion while more level ground leads to deposition.

Question 22

How does climate affect the formation of soil?

Answer 22

A warmer climate leads to faster breakdown of organic matter. More precipitation leads to more weathering, erosion, and deposition.

Question 23

How do organisms affect the formation of soil?

Answer 23

Soil organisms like bacteria, fungi, and worms breakdown organic matter.

Question 24

What are the different soil horizons?

Answer 24

O-horizon, A-horizon, B-horizon, and C-horizon

Question 25

What is the O-horizon?

Answer 25

The layer of organic matter on top of soil, such as plant roots, dead leaves, animal waste, etc. It provides nutrients and limits water loss to evaporation.

Question 26

What is the A-horizon?

Answer 26

The A-horizon is another name for topsoil. It’s the layer of humus (decomposed organic matter) and minerals from parent material. The A-horizon has the most biological activity (earthworms, soil microbes) breaking down organic matter to release nutrients.

Question 27

What is the B-horizon?

Answer 27

B-horizon is another name for subsoil. It’s the lighter layer below topsoil, mostly made of minerals with little to no organic matter. It contains some nutrients.

Question 28

What is the C-horizon?

Answer 28

C-horizon is the least weathered soil that is closest to the parent material. It’s also called bedrock.

Question 29

What is soil degradation?

Answer 29

The loss of the ability of soil to support plant growth

Question 30

What is nutrient depletion?

Answer 30

Nutrient depletion is the removal of key nutrients (N, P, K, Na, Mg) over time caused by repeatedly growing crops on the same soil. It reduces the soil’s ability to grow future crops.

Question 31

What leads to a loss of topsoil? What are the risks associated?

Answer 31

Loss of topsoil occurs when tiling (turning soil or agriculture) and loss of vegetation disturb the soil and make it more easily eroded by wind and rain. A loss of top soil dries out soil and removes nutrients + soil organisms that recycle nutrients.

Question 32

What is soil compaction?

Answer 32

Soil compaction is the compression of soil by machines (tractors, bulldozers, etc.), grazing livestock, and humans. It reduces soil’s ability to hold moisture. Dry soil erodes more easily because it supports less plant growth and less root structure.

Question 33

What are the three types of soil degradation?

Answer 33

Loss of topsoil, compaction, and nutrient depletion