Soil Types and its Properties

Summary

Soil has some characteristics that form the basis for its classification into various types, and also the types of crops that are grown in it.
These properties are,

     •  Absorption of water
     •  Moisture in the soil
     •  Percolation rate of water in soil

Absorption of water:  The capacity of the soil to hold water before it starts dripping is called its water absorption capacity. All types of soil do not absorb water in the same way.
This property of soil can be understood by performing an activity using plastic funnel with filter paper. A dry powdered soil is poured in the funnel. Now pour water drop by drop on the soil. Pour water evenly over the soil; continue pouring till the water starts dripping.
The percentage of water absorbed is calculated by using the following formula
U - V Solid Weight × 100
Where,
U= Initial weight of water
V = Final weight of water
 
Moisture in the soil:  
Soil moisture is the water content present inside it as moisture and it is available for evaporation.

Moisture content of the soil is mainly depends on the type of soil. Soil moisture plays a major role in the plant growth because plants always depend on the moisture content available at roots. The moisture content in the soil can be observed by heating a little bit of soil in a boiling tube.

Percolation rate of water in soil:  The phenomenon of absorption of water by soil is termed as percolation. The rate of absorption is different for different types of soils. The rate of absorption of a soil depends on its composition. A soil with more percolation rate can hold water for longer time. On the other hand a soil with poor percolation rate will hold water for longer time. Percolation rate helps in selection of suitable soil for crop growth.

  Percolation rate = Amount of water (ml) Percolation time (min)  

Types of soil:  Soil is not similar everywhere. Soil is classified into various types based on the appearance and proportion of particles. 
     •  Sandy soil
     •  Clay soil
     •  Loamy soil

Sandy soil:  Sandy soil is made of greater proportion of big particles like sand. They cannot fit closely together. So, there are large spaces between them. These places are filled with air. Therefore, in this type of soil, water absorption is very high as the water passes quickly through these spaces. These soils are light, well aerated and dry.

Clayey soil: Clayey soil is made of a relatively higher proportion of fine particles. Unlike sandy soils, these soils have very less space between particles. Because the particles are smaller in size, water can be trapped in the tiny gaps between them. Clay soils are heavy and hold more water.

Loamy soil:  Loamy soil is a mixture of sand, soil and silt. Silt particles are present between sand and soil particles. It also contains humus, and is, therefore, considered the best for the growth of plants. The percolation rate is between that of sandy soil and clay soil.

Soil and crops:  Climatic factors as well as the components of the soil determine the types of vegetation and crops that grow in a particular area.

     •  Cereals like wheat and gram are grown in clay and loamy soils, because these soils have better water retention capacity.
     •  Soils rich in clay and organic matter with good water retention capacity are ideal for paddy.
     •  Loamy soils, which drain water easily, are suitable for lentils and other pulses.
     •  For cotton, loamy or sandy soils are more suitable, because of their water draining and air logging capacity.
     •  Clay soils are rich in humus and fertile. These soils are very good for wheat.

Videos

Activities & Simulations

Activity1: 
Nationalzoo.si.edu has developed an interactive simulation. The simulation goes in interesting manner in explaining the properties of soil using both physcial and chemical tests.
Go to Activity

Activity2:
Glencoe.com has developed an interactive simulation regarding the properties of soil. This simulation is based on testing of different soils like sand, silt and clay. The test is based on water absorption capacity of these soils.
Go to Activity

Questions & Answers

1 . What is the difference between rate of percolation and the amount of water retained?
Also, Water is retained in small vesicles or spaces between particles of soil. Higher percolation occurs when there are large spaces betwee...
2 . explain that ,"soil is an inseparable part of our life."
Soil is defined as the naturally occurring, unconsolidated mineral or organic material at the surface of the earth that is capable of suppor...
3 . what is soil and name different types of soil
Ans: The upper layer of earth in which plants grow and which contains mixture of organic materialsis a black or dark brown material typicall...
4 . science urgent qs.
humus
5 . water and humus content in different soil types
Ans:  HUMUS - the organic constituent of soil, usually formed by the decomposition of plants and leaves. In most soil, the...