Soils

Question 1

What factors control soil formation?

Answer 1

Parent material, time, climate, biota, topography

Question 2

Why is soil important?

Answer 2

Soil is an important interface between all spheres on earth (lithosphere, biosphere, mesosphere, atmosphere, hydrosphere)

Question 3

Soil texture is comprised of what 3 things?

Answer 3

Sand, silt and clay

Question 4

What size is a coarse fragment?

Answer 4

Greater than 2 mm

Question 5

Gravels, cobbles and stones are called what?

Answer 5

Coarse fragments

Question 6

Name 4 properties of Sand

Answer 6

Feels gritty, excellent air supply to roots, large pores allow water to move quickly, generally resistant to compaction

Question 7

Name 4 properties of Silt

Answer 7

feels slippery or floury, small pores for increased water retention, easily compacted, less air supply than sand

Question 8

Name 4 properties of Clay

Answer 8

feels sticky, tiny pores hold water, compacts easily, air supply is restricted

Question 9

Name 4 properties of Organic Matter or Humus

Answer 9

feels slippery, holds water and nutrients, generally broken down into LFH layers and into Mor, Moder and Mull, cannot hand texture

Question 10

What contributes to soil structure?

Answer 10

texture, organic and mineral composition, water content, soil organisms, biological processes (e.g. root growth)

Question 11

Soil particles aggregate to form what?

Answer 11

a Ped

Question 12

What are the six types of soil structure?

Answer 12

Granular, Blocky, Columnar (or Prismatic), Platy, Single-Grained, Massive

Question 13

What system is used to determine the color of soil samples?

Answer 13

Munsell Color System

Question 14

Name the 10 soil orders in Canada

Answer 14

Brunisol, Cryosol, Chernozemic, Gleysolic,

Luvisolic, Organic, Podzolic, Regosolic, Solonetzic, Vertisolic

Question 15

Name the taxa used to classify soils (broad to narrow)

Answer 15

Order, Great Group, Sub Group, Family, Series

Question 16

What does CSSC stand for?

Answer 16

Canadian System of Soil Classification

Question 17

Name the 4 soil formation processes

Answer 17

1) Additions - the addition of organic material (i.e., addition of dead root mass in grassland ecosystems).
2) Transfers - the downward movement of soluble material in water (i.e., redistribution of calcium carbonate in a soil profile). Note that while the distribution of material with depth has changed, the material has not been completely lost from the soil.
3) Transformations - the weathering of primary minerals to secondary minerals, or the decomposition of organic matter.
4) Removals - the complete loss of material from the soil profile (i.e., the loss of calcium carbonate in a soil forming in a humid environment).

Question 18

Chernozemic soils are typically found in what types of environments?

Answer 18

Grasslands

Question 19

The youngest soils are found in what soil order?

Answer 19

Regosol

Question 20

This soil occurs in a wide variety of climatic and vegetative conditions and has brownish Bm or Btj horizons

Answer 20

Brunisol

Question 21

This soil is typically associated with coniferous forests

Answer 21

Podzol

Question 22

Name the soil where the dominant process is the eluviation of clay from the Ae horizon and its deposition in the Bt horizon

Answer 22

Luvisolic

Question 23

Which soil has a saline C horizon?

Answer 23

Solonetzic

Question 24

This soil is characterized by the shrinking and swelling of clays

Answer 24

Vertisolic

Question 25

Soil found in areas of temporary or permanent water saturation. Low chroma, prominent mottling, or both.

Answer 25

Gleysolic

Question 26

Soils that have accumulated organic materials in water-saturated conditions

Answer 26

Organic

Question 27

Name the Organic Horizons

Answer 27

O, L, F, H

Question 28

Permafrost soil found in arctic or sub-arctic conditions

Answer 28

Cryosol

Question 29

Name the 3 broad categories of Humus forms

Answer 29

Mor, Moder, Mull

Question 30

List some human activities (other than agriculture and forestry) that can have a direct impact on soil formation.

Answer 30

Road building, excavation, construction of various buildings, and mining.

Question 31

Why are A horizons more common in grassland soils than forest soils?

Answer 31

In grasslands, most of the organic matter is added directly to the mineral soil through dead roots and a significant amount of biomass is found underground. In forested ecosystems, above-ground biomass is much larger than below ground, while organic material is added to the surface of the soil where it tends to decompose before it is incorporated into the soil.

Question 32

How deep would the layer of topsoil on a hilltop be as compared to a valley below?

Answer 32

Soil at the top of a hill would be much thinner than in a valley because sediments move down slope.

Question 33

If all four processes are active in all soils, why aren’t all soils alike?

Answer 33

All four processes can and do occur at the same time in any given soil. It is the balance of these processes that determines the type of soil that forms. The balance of the four processes is controlled by the five soil-forming factors.

Question 34

The Ae horizons are more commonly present in soils that are under a vegetative cover of trees, rather than grasses. Can you think of why this might be?

Answer 34

Grasses tend to grow more quickly than trees in the spring and soak up more of the snow melt and early rainfall. Hence, more leaching takes place in soils under a vegetative cover of trees than grasses leading to formation of an Ae horizon.

Question 35

What is the difference between eluviation and illuviation?

Answer 35

Eluviation is the process by which clay is removed and illuviation is the process by which clay is deposited. Distinct eluvial and illuvial horizons may develop over time as water moves clay particles through the profile. The upper Ae (eluvial) horizon is depleted of clay and the lower Bt (illuvial) horizon is enriched with clay. Therefore, we can say that the eluviation of clay from the surface horizon created an Ae horizon, a horizon which is depleted of clay.

Question 36

What does the lower case “g” indicate about a horizon?

Answer 36

The “g” describes a horizon is gleyed or mottled and is usually characterized by grey colouring. This indicates the soil is permanently or periodically under intense anearobic conditions.

Question 37

List the Mineral Horizons

Answer 37

A, B, C