Clay soil explained with its types and characteristics

Clay Soil:

Clay soil is considered as one of the popular soil types. Their particles are fine-grained (less than 2 μm in size), and are made up of various minerals, especially aluminium phyllosilicates which includes Al₂Si₂O₅(OH)₄ (halloysite), Si₄Al₄O₁₀(OH)₈ (kaolinite) and Mg₃Si₂O₅(OH)₄ (serpentine). Meanwhile, understand that 'particle size' is a fundamental parameter in describing clay.

Other major components forming the raw materials of clay include illite, montmorillonite, micas, smectite, bentonite, vermiculite and chlorite; with these formed in the presence of water.

Please read on loamy soil here.

Variable amount of crystalline minerals (inorganic ions) are also present in clay. They include positively charged ions (cations) like potassium, magnesium, sodium, calcium and iron respectively. In this regard, clays are majorly considered as inorganic materials. These minerals have a great capacity to hold water and dissolved plant nutrients.

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From the above paragraph, it is quite clear that clay soils are rich in minerals (or inorganic compounds). However, they may still contain little organic material (humus). Pore spaces are very tiny in clay soils, resulting in the poor passage of air within it. Another implication of the negligible pore spaces between clay particles is the fact that only little water can penetrate it. For this reason, they can become easily waterlogged. This property of clay soil is quite contrasting to sandy soil.

Please read on sandy soil here.

Although clay soils are rich in minerals, they aren't still the ideal soil for cultivating most crops. However, they may still support the growth of certain crops like broccoli, potato, winter beans, winter wheat, spruce and pine tree.

Clay soil may contain other particles like sand, silt and loam. However, the amount of clay present alongside these particles (within a clay soil) is over 50%. This is shown below:

In comparison with other soil types, clay soil is quite denser (heavier), with a higher concentration of nutrients, and a higher water retention capacity.

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Weather conditions can significantly alter the shape of clay soils. On a wet environment, they can become sticky, and in this instance can attach to the shoes of whoever walks on it. Objects can also be moulded from it in this state. On the contrary, clay soil can become hardened (breakable) when dry.

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Clays are generally classified into two types based on their place of origin, alongside their deposited location. They include:

• Residual clay: They are formed from weathering, and are found at the location where the breakdown occured. Weathering in this regard include the chemical breakdown of rocks, alongside the solution of rocks and shale.

• Transported clay: As the name implies, they are displaced from their site of origin through erosion, and are deposited at a distant location. Transported clay are sometimes referred to as sedimentary clay.

  You can read on sedimentary rocks here.

Characteristics of Clay Soil

1. Clay soil can be red, brown, reddish brown or even white in color. The image below shows a reddish brown colored clay soil.
   
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2. The particles of clay soil are fine-grained with a size lesser than 0.002mm (< 2 μm), giving them a large surface area.

3. Clay soil typically retain large amounts of nutrients and minerals which can be somewhat beneficial to certain crops. This is so because soil nutrients aren't lost via leaching.
   Please read on soil erosion here.

4. When clay soil becomes wet, they develop plasticity, thus becoming sticky.

5. The structure of clay soil is dependent on weather conditions. In this regard, they have the capacity to swell when wet, and shrink when dry.

6. Since the particles of clay soil are closely packed together, they have little air spaces, and are thus poorly aerated.
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7. Inability of water to easily penetrate the closely packed particles of clay results into its waterlogging during rainy seasons.

8. Clay soil can become moldable into different objects. In fact, they are utilized in the production of ceramics through various processes.
   Please read more on ceramics here.

9. Although clay soil holds more total water compared to other soil types, their plants still suffer from drought as a result of the soil's inadequate release of its waters.

10. They often lack phosphate ions but contain the ions of alkali metals and alkaline earth metals.

11. Clay soil is quite acidic. Lime can be added to increase its pH, thus making it somewhat alkaline. This alkalinity results into the aggregation of clay particles into smaller clumps, thereby improving its quality as an agricultural soil.
    You can read on the physical and chemical properties of acids here.

12. Examples of plants that can thrive on clay soil include pine tree, crabapple, spruce, willows, balsam fir, tamarack tree and some maples. Animals that can survive within clay soils include ants, earthworms, millipedes , centipedes, termites and beetles.