GGR112 - Final prep

Chapters 15 - 21

Soil

A natural mixture of inorganic and organic particles that provide a suitable medium for terrestrial plants to grow

Pedology (soil science)

The study of the description, origin, distribution, and classification of soils.

Pedon

the most basic soil sampling unit (1 to 10 m2). \n - Pedons are described and categorized based on their soil horizons, which are defined as physically and/or chemically distinct sub-units.

Soil Formation

* Soils develop in-situ (in place) from regolith
* Soil evolution depends on __*principle soil forming factors*__
* __passive factors__: parent material type, topography, relief, time
* __dynamic factors__: climate, biology, humans
* Principle soil forming factors vary greatly by latitude and climate
* local differences like aspect, relief, and drainage are also important

Soil fertitlity

Fertile soil includes the following:

* Clay and organics
* Diverse community of microorganisms
* Basic plant nutrients (nitrogen, phosphorus, and potassium)
* Essential trace elements (Mg, B, Co, Cu, Fe, Mn, Mb, S, Zn)
* Neutral to slightly acidic pH (6.0 - 6.8)
* Good porosity and drainage

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\- Worms and burrowing organisms help improve porosity and drainage, and breakdown organic materials and return important micronutrients to the solum

Soil capability for agriculture (A- O)

A - Mineral soils __***capable of sustained production***__ of field crops, these soils require only normal conservation practices. Crop use __**limitations range from insignificant to moderately severe.**__

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B - Mineral soils of __***marginal capability for the sustained production of field crops***__. __**Severe limitations**__ influence crop choice, requiring special conservation measures to be employed.

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C - Mineral soils __***unsuitable for the sustained production of field crops***__. __**Very severe**__ limitations, restricted use to pasture and forage production.

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D - Mineral soils __***unsuitable for crop use***__ or permanent pasture. E__**xtremely severe limitations**__ don’t allow agriculture



O - Organic soils. not classified according to agriculture capability

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* Southern Ontario is mostly category A

Classes 1 - 8 no limitation and good to too many limitations and not good / organic

Soil Properties

* Colour
* Texture
* Structure
* Consistence (cohesion)
* Porosity
* Moisture
* Chemistry
* pH (acidity or alkalinity)

Colour Property

* Indicative of composition
* Munsell colour chart standard metric for soil scientists

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* Red soils - high iron oxide
* Dark brown to black - organic rich (southern Ontario)

Texture Property

* Soil texture triangle is used to determine the texture class based on known fracitons of sand, silt, and clay

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Hydrailic Characreristics:

* Sandier soils - faster drainage/low water holding capacity
* Clay-rich soils - slower drainage/ high water holding capacity

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loam - a balanced mixture of sand, silt, and clay beneficial for plant growth

* A sandy loam with clay

Soil ‘Ped’ Structure

* Soil structure - the arrangement of soil particles the smallest natural clump/ cluster of particles is called a ped.
* ped characteristics classify soil structure as granular, platy, blocky, prismatic/columnar
* as well as fine, medium, or coarse

Soil horizons (mineral a, b, c)

Eluviation - leaching of minerals and organics from a horizon

Illuviation - deposition of minerals and organics in a horizon

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A - eluviation of finer particles/minerals (leaching)

B - illuviation (deposition)

C - recieves little effect from processes in the A and B horizons

Soil orders

Regosolic - lacking B horizon, weak, A horizon is thin

Brunisolic - more developed than regosolic

Luvisolic - (toronto)

Podzolic - well developed A and B horizons, significant eluviation/illuviation

Gleysolic and Organic- poorly drained conditions (low oxygen, low rates of decomposition)

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