SOIL TYPES AND THEIR PROPERTIES

There are three major types of soil:

1.   Sandy soil

2.   Clay soil

3.   Loamy soil

PROPERTIES OF SANDY SOIL

1.   It is coarse, grained and gritty

2.   It is loose with large pore spaces

3.   It absorbs water and loses water easily

4.   It is not sticky when wet and cannot form cast

5.   It is well aerated with low water holding capacity

6.   Percolation in sandy soil is high but capillary is low

7.   Sandy soil is low in plant nutrients therefore it does not support crop cultivation

8.   Sandy soil has grey or brownish colour

METHODS OF IMPROVING SANDY SOIL

Sandy soil can be improved through the following agriculture practices:

1.   Planting of cover crops

2.   Application of compost manure

3.   Application of farm yard manure

4.   Mulching

5.   Avoidance of bush burning

PROPERTIES OF CLAY SOIL

1.   Clay particles are fine, powdery and smooth when dry

2.   The particles are sticky and muddy when wet

3.   Clay particles are closely packed together with little pore space

4.   Clay soil is poorly aerated with high water holding capacity

5.   It does not support leaching hence it contains plant nutrients.

6.   It is hard when dry and sticky when wet

7.   It can easily from cast when molded

8.   It supports water logging and erosion

9.   It has grey or brownish colour 

PROPERTIES OF LOAMY SOIL

1.   Loamy is moist, loose with moderated sized pore spaces

2.   The structure of loamy soil breaks easily when wet and friable

3.   It has non-powdery and non-sticky texture

4.   It can easily be cultivated or worked on

5.   It contains a lot of organic matter (humus)

6.   It does not support erosion and water logging

7.   It is well aerated and can hold water

8.   It is dark-brown or black in colour

9.   It has high content of nutrients and supports crop cultivation

SOIL COMPOSITION

The soil consists of major components namely:

1.   Mineral Matter : Different soil minerals such as Nitrogen, Phosphorus, Magnesium e.t.c

2.   Organic Matter: Dead and decayed plants and animals. Examples are: bones, feather, wings, shells of snails, flower etc.

3.   Soil Water: Water and others Solvents

4.   Soil Air: Air, Oxygen, Carbon e.t.c

 

SOIL TEXTURE

Soil texture can be defined as the degree of fineness or coarseness of soil particles when felt between fingers.

Also, Soil texture is the relative proportion of silt, sand and clay particles present in a given sample of soil.

METHODS OF DETERMINING SOIL TEXTURE

FEEL METHOD

This is the feeling of soil sample between fingers or the palm

WET METHOD

Under this method, a little water is added to the soil sample to make it wet and then feel it with fingers. Clay soil will stick, loamy soil will be very sticky and sandy soil will look moisturized (look wet).

LABORATORY METHOD

i.             Sedimentation

ii.           Sieving method

IMPORTANCE OF SOIL TEXTURE     

1.   It helps to determine the type of crop that will grow well on the land

2.   It also helps to determine the tillage practices required

3.   It is used to discover whether a particular soil is suitable for plant soil

4.   It helps to determine the type of crop that will grow well on the land

5.   It determines the ability of the soil to retain water

6.   It enables the farmer to know the type of soil available in his farmland

7.   It helps to determine the type of manure required

8.           It determine the relative resistance of soil to root penetration, under infiltration and air circulation

SOIL PROFILE

          This is the vertical cross-section cut through the soil which shows different horizontal layers of the soil called horizons. A good soil profile in an area of land has four distinct layers or horizon which are distinguished by colour or texture.

“A” Horizon is called top soil. It contains organic matters. It is dark in colour. It is the horizon of Alluviation.

Alleviation is the washing down of clay and aluminum minerals.

“B” horizon is called the top soil. It is very rich in clay and aluminum minerals because this is where the leached materials of “A” horizon is. Hence, it is known as the horizon of Elluviation.

Elluviation is the accumulation of minerals. It is brown or reddish orange.

“C” horizon is the zone of unconsolidated weathered material called the parents materials. The type of soil formed are the top soil and sub-soil.

(“A” and “B”) horizon depend on the parent materials on which they are derived or formed. This zone contains gravel and some coarse particles.

“D” horizon is called the bedrock which has never been disturbed by withering process. It is usually formed at the bottom of the soil profile.

IMPORTANCE OF SOIL PROFILE

1.   It helps the farmer to know the level of soil fertility

2.   It helps the farmer to know the type of crops that should be planted

3.   It determines the type of manure to use and the methods of application

4.   It helps to know the texture and colour of the soil

5.   It determines the depth and water retention capacity of the soil

SOIL STRUCTURE

          Soil structure is the arrangement of soil particles into aggregates. It is the way in which different particles of the soil are packed together and arranged. It can also be described as the physical appearance of the soil according to ways by which individual particles are held together.  

TYPES OF SOIL STRUCTURE

1.   Single – grained structure

2.   Platy or plate-like structure

3.   Blocky or block-like structure – There are two types they are:-

Blocky structure (Angular)       Crumb structure

 

Sub-angular Blocky structure         Single-granized             Car annular/spherical 

like structure                structure

 

Platy or plate like structure                      Prisonatic structure

 

Prism – like structure

IMPORTANCE OF SOIL STRUCTURE

1.   It determines the porosity and level of water retention

2.   It enables farmer to know the level of soil fertility

3.   It helps the farmer to know the type of crop that will do well on a particular soil

4.   It determines soil aeration and water movement in the soil

5.   It helps farmers to determine the types of manure to be applied

6.   It also helps to determine the tillage pratices to be adopted  

SIZES OF SOIL PARTICLES

          The various particles that make up a soil sample include:- gravel, sand, silt and clay. The sizes of these particles or soil fractions are used in the classification of soil texture e.g.

Soil particles	Sizes
clay	Below 0.0002mm
silt	0.002mm-0.02m
Fine sand	0.02mm-02mm
Coarse sand	0.2mm – 2.0mm
Gravel	Above 2.0mm