FACTOID # 13: New York has America's lowest percentage of residents who are veterans.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Soil horizons

Specific layers in the soil.

Soil is an intricate substance, and contains six primary components:
  • 1. Rocks and rock particles, constituting the greatest portion of the soil, and may become weathered, manumitting nutrients essential for plant growth.
  • 2. Humus, dead and decaying plant and animal matter that retains water, sustains soil oranisms, and providing nutrients.
  • 3. Dissolved Substances, including phosphorous, potassium, calcium, and other nutrients needed for plant growth.
  • 4. Organisms, including animals, like insects and worms, and many microorganisms, including bacteria and fungi.
  • 5. Water from precipitation, needed for plant growth and helping to circulate other materials through the soil.
  • 6. Air, sharing the porous spaces in the soil with water, necessary for respiration by the roots of plants and organisms living in the soil.
These materials are not evenly distributed in soils, but are found in layers, called soil horizons.

Soil horizons are made with the movement of water, minerals, and organic matter vertically through the soil, and by changes inn biological and chemical processes at different depths in the soil. In this way they are disimilar to layers in sediments, which are deposited in sequence from the bottom up.

The first horizon, located at the top, is comprised of accrued litter--leaves, twigs, dead bugs and such organic matter, and is called the O (for organic)horizon. As the litter decays, insects, worms, bacteria, and other oranganisms, consume and carry it underground, where it contibutes to the A horizon. The A horizon contains many of plant-supporting nutrients in many soils.
Water can erode substances from the surface of the soil, or carry some down from the A horizon the the B horizon. Chemical-weathering-formed clay minerals often aggregate in the B horizon. In some environments organisms help to trnsport materials between the A and B horizons. In arid climates, soluble substances like calcium accumulate in the B horizon. The C horizon, beneath the B horizon, contains weathered parent materials that more remain unaltered by soil-forming processes than the upper horizons.

  Results from FactBites:
 
Soil horizon - Wikipedia, the free encyclopedia (1114 words)
Soil horizons are made by the movement of water, minerals, and organic matter vertically through the soil, and by changes in biological and chemical processes at different depths in the soil.
The A horizon is the layer of soil at the mineral soil surface, and is roughly equivalent to topsoil.
The B horizon is the zone of illuviation, or translocation in.
Soil profile - Wikipedia, the free encyclopedia (207 words)
A soil profile is a cross section through the soil which reveals its horizons (layers).
Soil generally consists of visually and texturally distinct layers, which can be summarized as follows, from top to bottom:
When eluviation is pronounced, a lighter colored "E" subsurface soil horizon is apparent at th base of the "A" horizon.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m