Soil Structure

    Hello.... it's me..... again..... Onwards to the next topic.

    So for this week, we learned more about the soil structure and its importance. So before we go to that, we need to learn about the soil profile. Soil profile is the vertical section through the soil until it reaches the unweathered parent material and it show's the different layers of the soil. The layers of the soil is called horizons. Horizons are grouped in O, A, E, B and C horizons.

1) O horizon - Topmost layer, organic, fully or partially formed from decayed plant or animal debris. 

2) A horizon -  Topsoil, surface of mineral layer, darker colour than horizons below

3) E horizon - Most of leaching occurs here (clay, chemicals and organic matter)

4) B horizon - The layer which accumulates the leached matter (illuviation)

5) C horizon - Is usually the parent material, does not have the properties of A and B horizons

    As for the soil structure, they relate to the grouping or arrangement of the soil particles. They can be grouped further based on the aggregates. Aggregates are single particles that, when assembled, appear as larger particles. In general, soil structure can be described in terms of grade (aggregation degree), class (size) and the type of aggregate (form).

    In terms of grade, the structure can be classified as:

1) Structureless - no aggregation

2) Weak structure - poorly formed aggregates, easily breaks down when removed from profile.

3) Moderate structure - distinct aggregates, moderate durability, will break down into many aggregates when removed from profile.

4) Strong structure - well formed, durable

    In terms of form, they can be classified as:

A) Granular or crumb structure

    - individual particles of sand, silt and clay grouped together in small grains, high water circulation,

usually in A horizon

B) Blocky or sub-angular blocky structure

    - soil particles cling together in angular blocks, resist water circulation, usually in B horizon

C) Prismatic or columnar structure

    - formed into vertical column or pillars, poor water circulation and drainage, commonly in B horizon where clay accumulates.

D) Platy structure

    - soil particle aggregates into thin plates/sheets piled horizontally, greatly impairs water circulation, common in forest soil in A horizon

   

Picture obtained from Science Direct

  

  That's all from me, see ya later.