SOIL COMPONENTS AND THEIR PROPERTIES

APRESENTATION TO

FARMERS IN KPK BY ALLAH DAD KHAN

AGRICULTURE EXPERT KPK

BEGINNING OF SOIL 2,000,000,000 YEARS AGO

This is called the Pre-Cambrian period and is the earliest geological period. It is, of course, difficult to be sure what was happening so long ago but scientific research suggests soil formation began in this period. Compared to today, soil forming factors were very different so long ago. For example, there was no vegetation and few organisms to help to create the soil. It is thought that these earliest soils formed in an atmosphere with little or no oxygen and consisted of greenish clays.

BEGINNING OF SOIL 400,000,000 YEARS AGO

This is called the Devonian period. By this time land plants were becoming established and these required soils in which to grow. There was more oxygen in the atmosphere in this period and the soils were redder and browner, like some of our soils today. Various organisms developed and for the first time soil organisms began to play a part in soil development.

BEGINNING OF SOIL 354,000,000 TO 250,000,000 YEARS AGO Carboniferous times, which were 354 to 290 millions

years ago, were characterized by forests and swamps but there were major changes in the vegetation as the sub-tropical climate developed. The most striking soils from this era were the peat soils which eventually became buried and converted into coal. The Permian period dating from 295 to 250 million years ago also experienced a wide range of climate. Towards the end, conditions became hot and dry and desert soils developed widely.

BEGINNING OF SOIL 180,000,000 YEARS AGO

This was the Jurassic period, now well known for its dinosaurs, living in the subtropical conditions that were a bit like parts of Africa are today. By this time there was quite a wide range of animals, including soil organisms. The soils of this era would have resembled the subtropical soils of today, quite deep and reddish under the warm conditions that prevailed and capable of sustaining luxuriant pines and ferns.

THE ICE AGE, BEGINNING 2 MILLION YEARS AGO Many parts of the world have been affected by at

least one major Ice Age, resulting in the landscape being covered by ice. In some parts of the world there have been as many as four periods in the last 2 million years when the temperature has fallen and the land has become covered by an ice sheet. In these conditions pretty well all previous soils are scoured from the landscape and soil formation has to begin again. When the ice melted it left behind large deposits of mixed sediments. It is in this material that many of today’s soils have been formed.

SOILS OF TODAY

Although soil formation began 2000 million years ago, virtually all world soils are less than 1 million years old. The oldest soils are probably those found on some of the old landscapes of Africa. Most world soils are quite young and date back less than 10,000 years when the last ice sheets melted. Soils continue to form every day and even today somewhere there will be a new soil, perhaps on an exposed rock, beginning to form.

AIR ROLE IN ISLAM This element is no less important than water for the

perpetuation and preservation of life.  Nearly all terrestrial creatures are utterly dependent on the air they breathe.  The air also has other functions which may be less apparent to man but which God has created for definite purposes, as we have been made aware of by the Glorious Quran -such as the vitally important role of the winds in pollination.  God has said:

“Verily in the creation of the heavens and the earth; in the alternation of night and day in the change of the winds, and the clouds compelled between heaven and earth surely there are signs for a people who have sense.” (Quran 2:164)

“And He it is Who sends the winds as tidings heralding His grace: until when they have raised a heavy-laden cloud, We drive it to a dead land and cause the rain to descend upon it, and thereby bring forth fruits of every kind.” (Quran 7:57)

THE LAND AND SOIL IN QURAN

Like air and water, the land and soil are essential for the perpetuation of our lives and the lives of other creatures.  God has declared in the Quran:

1. “Have We not made the earth a vessel to hold the living and the dead?  And We have made in it lofty mountains and provided you sweet water to drink.” (Quran 77:25-27)

2. “And the earth, after that He has spread it out; from it He has brought forth its waters and its pastures, and He has made fast the mountains, a provision for you and for your cattle.” (Quran 79:30-33)

3. “And the earth, We have spread it out, and made in it mountains standing firm, and grown in it every thing in balance.  And We have provided in it sustenance for you, and for those whom you do not support.” (Quran 15:19-20)

4. “And a sign for them is the lifeless earth: We bring it to life and bring forth from it grain of which they eat.  And we have made therein gardens of palms and vines.” (Quran 36:33-35)

WATER IN QURAN 1. The Quran says (what means): “We sent down water

from the sky, blessed water whereby We caused to grow gardens, grains for harvest, tall palm-trees with their spathes, piled one above the other – sustenance for (Our) servants. Therewith We gave (new) life to a dead land. So will be the emergence (from the tombs).” [Quran 50:9-11]

2. And (what means): “We sent down water from the sky in measure and lodged it  in the ground. And We certainly are able to withdraw it. Therewith for you We gave rise to gardens of palm-trees and vineyards where for you are abundant fruits and of them you eat.” [Quran 23: 18-19]

3. And (what means): “We sent forth the winds that fecundate. We cause the water to descend from the sky. We provide you with the water – you (could) not be the guardians of its reserves.” [Quran 15:22]

SOIL PROFILE GALLERY

O: The O horizon is a surface horizon that is comprised of organic material at various stages of decomposition. It is most prominent in forested areas where there is the accumulation of debris fallen from trees.

A: The A horizon is a surface horizon that largely consists of minerals (sand, silt, and clay) and with appreciable amounts of organic matter. This horizon is predominantly the surface layer of many soils in grasslands and agricultural lands.

E: The E horizon is a subsurface horizon that has been heavily leached. Leaching is the process in which soluble nutrients are lost from the soil due to precipitation or irrigation. The horizon is typically light in color. It is generally found beneath the O horizon.

B: The B horizon is a subsurface horizon that has accumulated from the layer(s) above. It is a site of deposition of certain minerals that have leached from the layer(s) above.

C: The C horizon is a subsurface horizon. It is the least weathered horizon. Also known as the saprolite, it is unconsolidated, loose parent material.

SOIL HORIZON

SOIL COMPOSITION Soils are composed of four main components:

1. Soil Minerals of different sizes

2. Soil Organic materials from the remains of dead plants and animals

3. Soil Water that fills open pore spaces

4. Soil Air that fills open pore space ( Gases)

The use and function of a soil depends on the amount of each

component. For example, a good soil for growing agricultural

plants has about 45% minerals, 5% organic matter, 25% air,

and 25% water. Plants that live in wetlands require more

water and less air. Soils used as raw material for bricks need to

be completely free of organic matter.

1. SOIL MINERALS ( IN ORGANIC MATTER)

The largest component of soil is the mineral portion, which makes up approximately 45% to 49% of the volume. Soil minerals are derived from two principal mineral types. Primary minerals, such as those found in sand and silt, are those soil materials that are similar to the parent material from which they formed. They are often round or irregular in shape. Secondary minerals, on the other hand, result from the weathering of the primary minerals, which releases important ions and forms more stable mineral forms such as silicate clay. Clays have a large surface area, which is important for soil chemistry and water-holding capacity. Additionally, negative and neutral charges found around soil minerals influences the soil's ability to retain important nutrients, such as cations, contributing to a soils cation exchange capacity (CEC).

 

2.SOIL ORGANIC MATTER Organic matter is the next basic component that is

found in soils at levels of approximately 1% to 5%. Organic matter is derived from dead plants and animals and as such has a high capacity to hold onto and/or provide the essential elements and water for plant growth. Soils that are high in organic matter also have a high CEC and are, therefore, generally some of the most productive for plant growth. Organic matter also has a very high "plant available" water-holding capacity, which can enhance the growth potential of soils with poor water-holding capacity such as sand. Thus, the percent of decomposed organic matter in or on soils is often used as an indicator of a productive and fertile soil. Over time, however, prolonged decomposition of organic materials can lead it to become unavailable for plant use, creating what are known as recalcitrant carbon stores in soils.

3. SOIL WATER Water is a vehicle…a carrier…for the mineral nutrients. Later

in the course we will learn much more about water, but for now the critical features are that water is a great solvent for minerals and it dissociates.

The dissociation of water means, that in all situations water is not inert. It is in an equilibrium with different forms of itself. Water (H2O) can come apart (dissociate) to make a hydrogen ion (H+) and a hydroxide ion (OH-):

H2O ---- OH- + H+

The thin film of water around soil particles is the microscopic location of much of the important biology for the relationship between soil and plants. The water in these soil spaces is called capillary water. This water is tapped by the microscopic root hairs of the root for both water and minerals. A tree can go through hundreds of gallons of water in a short time and all of it comes from this thin film coating the soil particles and the root

hairs. This water contains the dissolved soil minerals.

4. SOIL AIR

Gases or air is the next basic component of soil. Because air can occupy the same spaces as water, it can make up approximately 2% to 50% of the soil volume. Oxygen is essential for root and microbe respiration, which helps support plant growth. Carbon dioxide and nitrogen also are important for belowground plant functions such as for nitrogen-fixing bacteria. If soils remain waterlogged (where gas is displaced by excess water), it can prevent root gas exchange leading to plant death, which is a common concern after floods.

SOIL FORMING FACTORS

1.Parent Material

2.Climate

3.Organism

4.Topography

5.Time

1. SOIL PARENT MATERIAL: This is the material from which the soil is formed.

Soil parent material can be bedrock, organic material, or loose soil deposited by wind, water, glaciers, volcanoes, or material moving down a slope.

2. CLIMATE: Climate also affects soil formation.  In hot climates, many

of the minerals will be oxidized, and the iron in the soil and clay will be a reddish color, rather than gray or black.  Organic matter will also decompose more rapidly in a hot climate, and within the great plains region, the native soils in Minnesota will be darker, and much higher in organic matter than those in Texas.  Rainfall also affects soil formation.  In areas of extremely high annual rainfall, some minerals, and in some cases, organic matter will have been leached from the topsoil to a lower layer.  The pH may be lower on these soils, due to the leaching of calcium from the topsoil.  Areas of low rainfall, especially where annual rainfall is less than the annual evaporation, will accumulate minerals, including calcium and other salts on the surface.

 

3.SOIL ORGANISMS/BIOLOGICAL PROCESS Biological processes that affect soil have historically been

determined by the native or natural vegetation.  Soils that form under forests are very different than those that have formed in grassland regions.  Much of the soil in the great plains was formed when the region was covered by prairie grasses.  This soil is very fertile, and rich in organic matter compared to soils of other regions.  The deep grass roots added organic matter to a depth of several feet in some cases, leading to the formation of the rich, dark soils that have made Kansas the "breadbasket" of the world.  Tillage, and planting of annual crops on these soils has halted this addition of organic matter, but reduced tillage and adding perennial crops into the rotation can help maintain the organic matter that is left. 

4. SOIL TOPOGRAPHY: Topography often affects how much erosion has taken

place.  Soils on top of hills or on steep side slopes tend to be thinner, or more eroded than those on the slopes, and at the bottom or "toe" of a slope, one can find zones of soil accumulation.  Management, along with topography will also affect how much erosion has, and is continuing to take place.  The thinner, or more eroded soils will often be lower in organic matter, since they have lost their topsoil layer.  The clays in the subsoil layers are then on the top.  A field that is "patchy" in color will probably have had some erosion historically.

5.TIME: The time that a soil has had to form will often affect the amount of

layering, or differentiation from the top of the profile to the bottom.  An older soil will have a "topsoil" layer, that will be darker, and higher in organic matter (from centuries of contributed plant and animal matter), and the lower layers will be progressively lighter in color, and generally lower in organic matter and nutrient content.  An example of a "young" soil would be an area where a river has recently deposited soil, or alluvium, to a particular area.  In parts of the world with active volcanoes, the volcanic ash layers will begin to form soil layers, and then may be covered again by ash.  In some of these areas, one can find buried soil horizons.  A soil that is nearly the same color throughout the profile, especially when there is little change in the

properties of the profile horizons is probably a young soil..

THE NUTRIENT CONTENT OF SOIL NOW WILL BE A COMBINATION OF; 1) the starting natural fertility of the parent material (Kansas

soils, for example, tend to be naturally high in potassium),

2) the subtraction of nutrients as a result of erosion and crop use since the land has been tilled (generally for the past 100 years or so), and

3) additions of fertilizer sources such as manures, composts, legumes, and mineral fertilizers. 

When designing a soil sampling program, one needs to consider all of these factors.  Knowing the soil type (from soil survey maps), topography, and field histories (crops grown and fertility sources) will help you design a plan to answer specific farm management questions.

 

SOLI AS LIVING BEING 1. The soil is an ecosystem in which millions, even billions, of

living creatures live and interact. Rather little is known about this huge population because for the most part they are underground and out of sight.

2. The soil ecosystem has been declared by some scientists to be the last great biotic frontier that we need to discover. One thing we do know is that there can be more organisms in a teaspoonful of good soil than there are people in the entire planet earth -that is more than 6 billion. Wow !

3. There is a very wide range of organisms in the soil, ranging from protozoa which require the strongest of microscopes to detect them, up to large burrowing animals like badgers and rabbits which can readily be seen with the naked eye.

It takes 500 years for a centimetre of soil to form

SOIL TEXTURE 1. When you take some moist soil in your hand and rub it

between your fingers, you will feel the texture of the soil. In particular, you will be able to detect whether the soil feels rough or coarse, in which case it is probably a sandy soil, or whether it feels smooth which is the feel of a clayey soil.

2. The amounts of sand, silt, clay and organic matter in a particular soil play a large part in the way that it behaves, how it can be managed and what it can be used to grow.

3. Sandy soils are easy to cultivate but tend to hold little water and may be droughty, whereas clay soils are more difficult to cultivate, hold a lot of water and can become waterlogged, especially in winter

SOIL STRUCTURE Just as houses and buildings have a structure or architecture, so

also does the soil.

1. The particles of sand and clay that make up the soil rarely occur as separate particles but are more or less loosely combined into aggregates.

2. The type of structure in soil depends to a large extent on the texture and the amount of organic matter in the soil and the way the land is managed.

3. The aggregates that make up the structure may be as small as a few millimeters, such as granules and crumbs, or as large as several centimetres, such columns and prisms.

4. The granular or crumb structure is the one favoured by farmers and gardeners as it makes a better bed for the seeds they plant

THE SIZE OF SAND, SILT AND CLAY

Name Particle Diameter

Clay below 0.002 millimeters

Silt 0.002 to 0.05 millimeters

Very fine sandFine sandMedium sandCoarse sandVery coarse sand

0.05 to 0.10 millimeters0.10 to 0.25 millimeters0.25 to 0.5 millimeters0.5 to 1.0 millimeters1.0 to 2.0 millimeters

Gravel 2.0 to 75.0 millimeters

Rock greater than 75.0 millimeters (~2")

SOIL PARTICLE SIZE

SOIL CHART

SAND PARTICLES 1. Forms free draining soils

2. Largest mineral particle size - between 2mm and 0.06mm in diameter

3. Feels gritty to touch

4. Makes a rasping sound when rubbed together

5. Particles do not stick together and cannot be made into a ball

6. Soils warm quickly in Spring, but cool quickly in Autumn

7. Forms soils which cannot hold onto nutrients

8. No swelling or shrinkage in the soil

9. Can not hold onto nutrients

SILT PARTICLES 1. Forms soils which can be hard to drain

2. Holds on to a moderate amount of water

3. Medium mineral particle size - between 0.06 and 0.002mm in diameter Feels soapy or silky

4. Makes a squeaky sound when rubbed together

5. Particles don’t easily hold together - a ball of them breaks easily

6. Soils warm and cool more quickly than clay, but less quickly than sand

7. Forms soils which can only hold limited nutrients

8. Limited swelling or shrinkage in the soil

9. Makes very fertile soils

CLAY PARTICLES 1. Forms soils which readily become waterlogged Becomes

heavy when wet

2. Smallest mineral particle size - diameter less that 0.002mm

3. Feels smooth when dry and sticky when wet

4. Makes very little sound when rubbed together

5. Particles stick together and are easy to make into a ball

6. Soil takes a long time to warm up in Spring and to cool down in Autumn

7. Forms soils which can hold onto nutrients Soil swells when wet and shrinks when dry

8. Can be used to make bricks or pots

DIFFERENT TYPES OF SOIL

Soil is nothing but a thin layer on the surface of the Earth. It is the medium through which plants gather their nutrients. Depending on the size of the particles present in the soil, it is divided into various

types.

 SOIL TEXTURE AS DEFINED BY SOIL TEXTURAL CLASS AND ESTIMATED BY HAND

SOIL SEPARATE AND TEXTURAL CLASSES

SANDY TYPE SOLIS1. Warms much more quickly in Spring because of less water retention

2. Are light and easy to work having less essential nutrients.

3. Are free-draining ,water drains rapidly

4. Can dry out in dry weather

5. Tend to be low in nutrients

6. Can be worked at almost any time

7. Need liming little and often.

8. When we roll the slightly wet sandy soil in our palms, no ball should be formed and it crumbles through your fingers

9. Ideal for crops like:Watermelons, Peanuts, and Peaches

10. Ideal for plants like:Tulips, Cistus, and Hibiscus

SILTY TYPE SOILS1. Deposited by rivers and lakes , not grainy or rocky

2. Warm up quicker than clay but slower that silt soils in Spring

3. Silty soils retain water longer than sandy soils

4. Difficult to drain, but less likely to waterlog that clay

5. Tend to be fertile and good for agriculture purposes.

6. Silty soil can also easily compact, so avoid trampling on it when working your garden. It can become poorly aerated, too

7. When we roll it between your fingers, dirt is left on our skin.

8. Ideal for crops like:All vegetables and fruits

9. Ideal for plants like:Yellow Iris, Milkweed, and Red Chokeberry

CLAY TYPE SOILS1. Clay soil is cold and in the spring, takes time to warm since the water

within also has to warm up

2. Heavy soils needing well-timed cultivation

3. Lie wet and prone to water logging ,retains water , sticky when wet.

4. Tend to be rich in plant nutrients for better growth.

5. Should not be worked when wet Need regular liming

6. Rolls up easily, and forms into a ball or sausage-like shape, then you’ve got yourself clay. Ideal for crops like:Leafy vegetables, Peas, Tomatoes, and Peppers

7. Ideal for plants like:Roses, Heleniums, Asters, and Chaenomeles

LOAMY SOILS 1. Contain a mix of sand, silt, and clay particles

2. It contains a balance of all three soil materials—silt, sand and clay—plus humus.

3. It has a higher pH and calcium levels because of its previous organic matter content.

4. Warm up fairly early in Spring , soft and crumby

5. Are easy to work Usually need draining

6. Should not be worked when wet

7. Tend to be rich in nutrients

8. Ideal for crops like:Tomatoes, Carrots, Parsnips, and Potatoes

9. Ideal for plants like:Roses, Amaryllis, Marigolds, and Zinnias

CALCAREOUS / CHALKY SOLIS 1. Come from chalk and limestone rocks , light in colour , lime

rich soil

2. Contain calcium carbonate and flints

3. Tend to be alkaline

4. Usually free-draining

5. May be low in some nutrients

6. Do not usually need liming

7. Poor in nutrients , warm quickly in summer

8. Ideal for plants like:Honeysuckle, Jasminum, Rosa, and Geranium

PEATY TYPE SOILS1. Dark brown in colour, soft and spongy to the touch ,so

warm up quickly in Spring

2. Hold on to water well and can be easy to work , protect the roots from damage during very wet months , rich in organic matter

3. Come from the build up of dead rotted plants, so contain lots of organic matter

4. Tend to be acid Usually high in Nitrogen

5. When wet peat soil is rolled, you won’t form a ball. It’s spongy to the touch and when squeezed, water could be forced out.

6. Ideal for plants like:Sphagnum Moss, Ericaceous Shrubs, and Sedges

SALINE TYPE SOILS 1. The soil in extremely dry regions is usually

brackish because of its high salt content

2. The salinity is due to the buildup of soluble salts in the rhizosphere—high salt contents prevent water uptake by plants, leading to drought stress.

3. It’s easy enough to test if you have saline soil. You’ll probably see a white layer coating the surface of the soil, your plants are growing poorly, and they’re suffering from leaf tip burn,

especially on young leaves.

A teaspoon of soil contains more

creaturesthan there are people on the whole planet!