Soil characteristics Flashcards

What ancient environmental condition formed the bedrock found in present-day Ontario?

Ancient seas containing coral reefs

What characterizes an Of organic soil horizon?

Composed of fibric material that has not decomposed, leaving plant structures (like leaves) intact.

What field method is required to properly assess small-scale soil variability?

Digging soil pits

What soil condition is indicated by the horizon suffix 'g'?

Evidence of reduced conditions (gleying due to waterlogging/poor drainage).

Why is small-scale soil variability often omitted from large-scale soil maps?

They do not cover small-scale variability, and map makers generally do not dig soil pits to assess localized variations.

How can soil temperature assist plant growth when air temperatures are cold?

Soil temperature can be considerably different from air temperature, allowing the soil to provide heat to plants.

How does carbon movement differ between managed agricultural ecosystems and natural ecosystems?

In managed ecosystems, carbon is transported off the land via harvest, whereas in natural ecosystems, carbon/plant material is returned to the soil.

Which four environmental spheres border and interact to form the pedosphere?

Lithosphere (earth crust), Hydrosphere (water), Biosphere (living things), and Atmosphere

What layer condition is designated by the horizon suffix 'z'?

A layer of permafrost

How does excessive salt content in soil harm plants?

It alters osmotic potential, inhibiting the plant's ability to take up water.

What chemical presence is indicated by the soil horizon suffix 'k'?

Calcium salts

What process is indicated by the horizon suffix 'y'?

Cryoturbation (soil mixing caused by freeze-thaw action).

What proportion of total soil volume is composed of solids versus pore space?

50% solids and 50% porous space

What four primary soil conditions or properties can be inferred from soil color?

Mineralogy, oxidation state, organic matter content, and drainage

Which major soil horizon letter represents the subsurface mineral horizon directly below the A horizon?

Horizon B

In soil horizon classification, what does 'eluviation' mean?

The exit or loss of soil materials (such as minerals or iron) from an upper soil horizon.

What structural feature is indicated by the horizon suffix 'ss'?

Slickensides (smooth, slick surfaces produced by clay movement/swelling)

Which mineral element is present in small amounts in most soils and strongly influences soil color based on oxidation state?

Iron

In the Munsell soil notation 10 YR 4/3, what do the numbers '4' and '3' represent?

'4' represents the Value (lightness), and '3' represents the Chroma (color intensity / spots over).

In soil horizon classification, what does 'illuviation' mean?

The introduction or accumulation of leached materials (such as iron or clay) into a lower soil horizon.

What is the primary defining characteristic of a C horizon?

It is relatively unaffected by pedological (soil-forming) processes.

What physical feature does the soil horizon suffix 'v' denote?

Vertical cracks

What defines a Bm horizon?

A subsurface horizon that has been slightly altered by pedological processes.

What four basic material components make up the solid portion of soil?

Organic matter, clay, sand/minerals/rocks, and organisms

Approximately how old are the oldest soils in Guelph, Ontario, and what caused this age boundary?

10,000 to 15,000 years old, due to the last ice age glacial activity.

How does cryoturbation mechanically disrupt soil layers?

Freezing causes expansion, forming large ice lenses that heave and mix the soil horizons.

Presence of which compound often causes a naturally high soil pH?

Carbonate

What standardized tool do soil scientists use to describe and classify soil color?

Munsell Soil Color Chart

What degree of decomposition characterizes an Om organic horizon (mesic)?

Intermediate stage of decomposition

According to soil science, what is the minimum thickness required for a naturally occurring material to be defined as soil?

At least 10 cm

Why is sodium-affected soil significantly worse for soil structure than general salt-affected soil?

Sodium pushes clay layers apart by disrupting chemical bonds, causing soil structure collapse and poor drainage.

What defines an Oh organic soil horizon?

An organic horizon composed largely of humic material ('h' for humus) that is dark in color and extremely decomposed.

What causes the formation of an Ap horizon instead of an Ah horizon?

Human disturbance through agricultural cultivation/plowing.

What two components occupy the porous space of soil?

Air and water

What is the LFH layer in forest soil profiles?

The top leaf litter layer containing thin organic material fallen from trees.

What are the key visual and compositional characteristics of an Ae horizon?

It is a light-colored surface horizon with no added organic matter that has been heavily impacted by eluviation.

Which three physical features of soil were majorly impacted by past glacial environments?

Particle size, topography, and drainage

What is an Ah horizon?

A dark-colored surface mineral horizon enriched with organic matter.

Which region in Ontario is noted for containing substantial organic soils?

Holland Marshes

The layer of Earth represented by soil where all environmental spheres meet is called the _____.

Pedosphere

In the Munsell color notation 10 YR 4/3, what does '10 YR' represent?

The hue page in the Munsell chart

Why is fertilization necessary in managed agricultural ecosystems compared to natural ecosystems?

Crop nutrients are finite and removed with harvest in agriculture, whereas in natural ecosystems, most nutrients taken up by plants are returned to the soil.

Under what pH conditions does iron become highly mobile and move downward in soil?

Acidic conditions

What presence is indicated by the horizon suffix 's'?

Soluble salts (any ions in solution, including plant nutrients).

A subsurface B horizon enriched with clay that moved down from the A horizon is designated as _____.

Bt horizon

What element accumulates in a Bn horizon, and where in Canada is it commonly found?

Sodium; commonly found in the Prairie provinces.

What does the suffix 'f' signify in a Bf subsurface horizon?

Enrichment with iron and aluminum that have eluviated from upper horizons.

What energy source drives the water cycle that heavily impacts soil?

Solar energy