Env 234 Lecture 10

Front 1

how does the biosphere connect to thelithosphere

Back 1

through soil

Front 2

how is soil the essential foundation for all terrestrial life

Back 2

through its nutrients, through its retention of water, and through its role as a substrate for plant rooting

Front 3

in the absence of organisms, would soil form?

Back 3

no

Front 4

how does soil form?

Back 4

through the action of organisms from the biosphere and of atmospheric processes on parent material belonging to the lithosphere

Front 5

how are rock layers different from soils?
(horizons vs layers)

Back 5

-soils are stratified like rocks but theres a difference
-rock strata form from accumulation of layers (laid down during sedimentation or by successive igneous outbursts

Front 6

What are soil strata called?

Back 6

horizons

Front 7

what are the characteristics of soil strata (horizons) in contrast to rock strata?

Back 7

-soil strata are horizons
-they form within a pre-existing mass of material.
-soil, as a whole, is produced by both biotic and abiotic processes acting progressively on an underlying parent material to mature a sequence of horizons differing from the parent material and from each other.

Front 8

what are basic processes to create horizons?

Back 8

•Weathering (chemical & mechanical)
•Leaching
•Fragmentation
•Incorporation

Front 9

what is the atmospheric component in creating soil

Back 9

•Water
•Wind
•Electromagnetic radiation
•Chemicals (mostly acidity, but some gases)
•Temperature

Front 10

what is the biotic component in creating horizons of soil

Back 10

•Plant litter (bulk organic matter & acids)
•Root penetration (mechanical & exudates)
•Macrofauna (mammal burrows)
•Mesofauna (earthworms, woodlice, etc.)
•Microfauna (nematodes, protozoans, etc.)
•Microflora (bacteria & fungi)

Front 11

how does the description and classification soils vary from country from country

Back 11

-Every country has its own specific approach to soil classification
-based on different descriptive elements among all those possible.

Front 12

what is a pedon?

Back 12

Canadian terminology:
The smallest unit or volume of soil that contains all the soil horizons of a particular soil type

Front 13

what is non-universality?

Back 13

Every individual soil has a unique history not shared with any other soil.
[Like rocks and rock formations and unlike organisms.]
Different countries have quite distinct arrays of soils and different land use characteristics.

Front 14

in the united states where do soil classifications start?

Back 14

anything below the depth of the plow

Front 15

in the united states why do their soil classification ignore anything above the depth of the plow? Is this the case with Canada? why?

Back 15

In the United States, much of the land has been under cultivation for centuries
upper portions of the soils are repeatedly disturbed by plowing
no because most of Canada’s land surface is not cultivated, so the whole profile is taken into consideration for description and classification.

Front 16

What are elements of description of horizons of soil?

Back 16

•Presence, characterization, & thickness of horizons in a soil pit or core (potentially extending as deep as bedrock)
•Particle size distributions (clay/silt/sand)
•Chemical composition (nutrients & toxins)
•Quantity and state of organic matter
•Friability & pore structure (infiltration)

Front 17

what are the standard horizons of soil?

Back 17

•L – intact litter
•F – partly decomposed litter
•H – fully decomposed litter
•A – leached and/or with organic matter
•B – variously altered incl. mineral precip.
•C – relatively unmodified
•R – consolidated bedrock

Front 18

what are the standard horizons of holland marsh

Back 18

Just two horizons:
•O – peat
•W – water

Front 19

what are modifiers?

Back 19

part of Canadian system of soil description and classification,
each of the capital letters for the horizons present can be (and usually is) accompanied by one or more lower case letters giving greater specificity, such as

Bf – for a B horizon with significant amounts of precipitated iron.

Front 20

how does leaching and precipitation affect soil horizons?

Back 20

A, B, & C horizons basically develop as a result of leaching and precepitation
of minerals from near the surface (A horizon) by rainwater and organic acids from the decomposing litter and their re-deposition in the B horizon
in the B horizon they reach more basic (calcareous) material (especially in southern Ontario). Carbonates (of calcium & magnesium) may precipitate out in the C.

Front 21

how does soil develop?

Back 21

Soil development can occur in the absence of pedofauna (especially the mesofauna), but it is a much slower process.
Since all of our earthworms and woodlice are introduced from Eurasia, pre-Columbian soil development at Joker’s Hill, for instance, would have taken far longer than it does today.

Front 22

what is Canadian soil classification?

Back 22

The Canadian system of soil classification is a fairly elaborate hierarchy of ranks, including:
Order
Great Group
Subgroup
Family
Series

Front 23

what are the soil orders in Canada

Back 23

There are nine of these defined in the system based on differences in present characteristics and modes of origin:
Brunisolic, Chernozemic, Cryosolic, Gleysolic, Luvisolic, Organic, Podzolic, Regosolic, and Solonetzic

Front 24

What are the soil orders in ontario?

Back 24

Most pedons (soils) in Ontario fall into the Brunisolic (deciduous forest zone), Gleysolic (fens & other shallow water wetlands), Luvisolic (drier forest and open areas), Podzolic (boreal forest zone), and Organic (bogs) orders.

Front 25

what two features of soil are particularly important for plant growth?

Back 25

•Amount of mineral nutrients (new versus old soils)
•Position along the conventional moisture gradient

Front 26

what is the moisture gradient of soil?

Back 26

•Dry (periods of profound drought, anaerobic)
•Dry mesic
•Mesic (always sufficient moisture)
•Wet mesic
•Wet (periods of water loggin, anaerobic)

Front 27

what are factors affecting soil moisture?

Back 27

•Precipitation
•Slope (ability for water to drain away)
•Aspect (N vs S facing slope)
•Particle size
•Organic matter

Front 28

what makes unfavourable soil?

Back 28

•Droughty
•Waterlogged
•Poisonous
Heavy metals (serpentine-derived soils)
Organic toxins (including allelopathy)