What is Soil?

“ Soil is the hidden, secret friend, which is the root domain of lively darkness and silence” Francis Hole

“a living, dynamic system with organic and inorganic components “a living, dynamic system with organic and inorganic components. Soil is a product of its environment and parent material”.

components By volume: By mass? 45% mineral 5% organic material 50% space (air/water) By mass? 0% air 18% water 80% mineral 2% organic material

1. The mineral component inorganic “mineral”: definition? Primary: original components of earth crust Secondary: new minerals made by weathering of earth’s crust divided by particle size: Sand, silt, clay

mineral make-up due to: a. Parent Material b. How resistant minerals are c. Climate d. “Age”

a. parent material material on and in which soil develops

Examples of soil developing IN rather than ON parent material: 1 Examples of soil developing IN rather than ON parent material: 1. Apostle Islands

2. Boundary Waters

11 different parent materials …..

Regolith/bedrock: weathered rock

Alluvium: deposits on a flood plain from a river

Marine deposits: shell, reef and other “bits” formerly at bottom of ocean that have been uplifted

Lacustrine deposits: clay deposits originally laid down at the bottom of a lake; lake is no longer there

Example: glacial lakes in MN

Till: unconsolidated material deposited by glacial ice

Outwash: unconsolidated, sorted material deposited by meltwater from a glacier

Organic sediments: peat

Volcanic ash

Loess: deep deposits of silt that have been deposited by wind

Sand: beach sand, dune sand

Colluvium; material that moved downslope, as in a landslide

mineral make-up due to: a. Parent Material b. How resistant minerals are c. Climate d. Age

b. resistance of minerals Soluble minerals are readily LEACHED from soil profile (Ca,Mg,Na) Certain minerals tend to accumulate in soil (oxides of Fe, Al, Si)

c. Climate Amount of leaching Rate of weathering

d. Age Parent material is (usually) less influential in “older” (more highly developed) soil

2. Organic Component Living (primarily decomposers) Non-living (dead and all in-between stages of decomposition)

3. The Space component Soil pores filled with air and/or water

A. soil air O2 CO2 N2 H 2O vapor (per cents by volume) (rh) Above-ground atm. 20.97 0.03 79.0 <100% Soil (grassland) atm. 18.4 1.6 79.2 100 %

B. soil water Functions? Polar molecule