ssc 10 chapter 1

soil horizons

layers of soil with different physical and chemical properties that are different from adjacent layers above and below

soil characteristics

horizons, color of horizons, texture (sand, silt, clay), structure, density, chemical properties (pH), redoximporhpic feeatures (reduction and oxidation)

soil profile

vertical section of soil exposing all layers of soil

A horizon

surface horizon

C horizon

not much weathering; not much structure; less water

B horizon

accumulates stuff; is the illuvial layer; most development; weathered

O horizon

organic matter

E horizon

elluvial; material moves out to layer below

R horizon

rock

what is the order of soil horizons

A, E, B, C, R

Soil forming processes in soil horizons

additions, redistribution, losses, transformations

additions

leaf litter, deposition, flooding, etc

redistribution

moving soil/material, E horizon to B horizon, moving material up or down

losses

erosion, decomposition (carbon → co2), down movement with h2o

transformations

mineral weathering, microbial processes

topsoil

A horizon, organic matter, most plant roots grow here; nutrient uptake; microbial activity

microbial activity

biological activity done in soil by microorganisms

sub soil

B horizon; lower organic matter; more developed; provides water under drought circumstances; important for engineering

Oi

slightly decomposedO

Oe

Medium decomposed

Oa

highly decomposed

what order are soil horizons formed?

1. c horizon

2. A forms as organic matter are added to upper part of profile

3. B forms as salts and clays accumulate in deeper zones

4. E forms between A and B after A material goes through it

how are transition horizons named?

Dominant horizon letter is listed before the subordinate one; Ex: AB, CB, etc