INTRODUCTION

• Soil is the unconsolidated mineral

material on the immediate surface of

the Earth

• It serves as a natural medium for the

growth of terrestrial plants.

CONTENTS • Definitions of soil

• Soil formation

• Components of soil

• Properties

• Functions

• Classifications

• Factors affecting soil quality

• Soil testing

• Ayurvedic concepts of soil

• Conclusion

DEFINITIONS OF SOIL

Geologic definition- Loose surface of the

earth as distinguished from solid bedrock.

Traditional definition: Material which

nourishes and supports growing plants.

ORIGIN

Rocks

Minerals

Organic Matter

Soil formation factors

Type of Parent Material

Climate

Topography

Biotic Components

Time

Rock &

mineral

Parent

material Soil particle

Physical

chemical &

biological

Soil formation

Environmental settings& soil

formation

• Luterization; rapid decomposition&mineral

leaching(eg.in tropics)

• Podzolization; Acidic leaching(eg.in cool,moist)

Gleization ;Slow decomposing (eg.in cool water

lodged areas)

Calcification;Limited leaching concentrates

chemicals in B horizon

• Salinization;Salts accumalte due to inadequate

drainage (eg.in desserts)

Laterization:

• Rapid decomposition & mineral leaching

typical where climate is warm & moist (e.g.

Tropics!)

• Most minerals, including silica are

leached out resulting in low fertility

• Iron & aluminum are left behind &

give soil a red color

Podzolization:

• Where chemical weathering is slow but acids in

plant material & adequate moisture make

leaching very effective.

• Typical of Boreal Forests.

• Produces shallow acidic soils w/ distinct profile

• – A horiz is leached/bleached

• – B receives iron-aluminumoxides & has reddish

color

• Fertility is generally low & soil is easily erode

Gleization:

• Where waterlogged environments slow

decompositionof organic matter

• Usually found where land is flat, in

depressions, or where water table is high

• Sticky & hard to till

• Generally acidic & oxygenpoor

• OK for water-tolerant vegetation but needs

artificial drainage & ph treatment for other

plants

Calcification

• Arid conditions restrict leaching &

concentrate chemicals in B horizon.

• Calcium carbonate often forms hardpan in

B horizon & further limits loss of

water/nutrients

• Nutrients remain available to plants

• Excellent fertility

Salinization:

• Salt accumulation due to inadequate

drainage.

• Common in desert areas & where soils are

over irrigated

SOIL HORIZONS

• As soils develop they form layers called

Horizons.

• These horizons have distinct characteristics

produced by soil forming processes.

• Master horizons include the O, A, E, B, and C

horizons.

• Not every soil contains every horizon based on

the level of development of the soil.

• Depth of each horizon varies between different

soils.

LAYERS OF SOIL

COMPONENTS OF SOIL

• Mineral matter

• Air

• Water

• Organic matter

Soil Components (volume basis)

basis)

I. Mineral constituents

Forms the bulk of the solid phase of the

soils.

Comprises carbonates,soluble salts,free

oxides of iron,aluminium & silica in addition

to some amorphous silicates.

Soil saturated with ca and mg is considered

normal and fertile

II. ORGANIC MATTER

• Main source is plant tissue and subsidiary

animals.

• Influence soil in respect to colour, physical

properties

• Play vital role in productivity of soil.

III. SOIL AIR

• Ideal for plant growth 1/3 pore space by

air &2/3 by water.

• Composed of N2,O2,CO2 & moisture

content.

IV. SOIL WATER

Function

serves as solvent & carrier of

plant nutrients

TYPES OF SOIL WATER

• Capillary water - filled in micro pores

• Gravitational water – free water, moves

downwards

Physical properties

1. Particle shape – vary from spherical to angular

2. Particle size – differ from gravel & sand to fine clay

3. Soil texture – particles of different size

(gravels,sand etc)

4. Colour – due to mineral or organic matter

cont…..

….contd PHYSICAL PROPERTIES

5. Pore space – occupied by air & water

sands 30%,clay 50%-60%

6. Soil temprature – Controls micro biological

activity,proccesses in plant growth.

7. Soil structure – arrangement of soil

particles

Functions affected by soil

textureSoil property Sand silt clay

aeration excellent good poor

drainage excellent good poor

Nutrient-holding

capacity

low medium high

Water-holding

capacity

low medium high

1.Observed:soilprofile,composition,

texture, or particle size

2.Measured: pH and permeability

SOIL PROPERTIES

Litter – organic matter on top

Topsoil- nutrient rich top layer, for

plant growth

Subsoil- under topsoil, small rocks

Bedrock- semi solid rock

Soil profile

Texture - size of individual soil particles.

Determined by- proportions of sizes that

make up soil

Particle size range -tiny (clay) to > 2 mm

(gravel)

Soil texture

Open spaces allowing water to flow

through it.

How freely water flows is called

permeability.

Used to understand drainage

Soil permeability

Soil can be acid-like or base-like depending on

measure of pH

Soil pH range is 4-10 with lower numbers being

acidic

Healthy soil is between 5-7

Soil pH

SUITABLE PH FOR Vegetables

PLANT TYPE SOIL Ph

Asparagus 6.0-8.0Beets 6.0-7.5Broccoli 6.0-7.0Cabbage 6.0-7.5 Carrot 5.5-7.0 Cauliflower 5.5-7.5Celery 5.8-7.0Cucumber 5.5-7.0Lettuce 6.0-7.0Muskmelon 6.0-7.0 Onion 5.8-7.0 Potato 4.8-6.5 Rhubarb 5.5-7.0Spinach 6.0-7.5Tomato 5.5-7.5

Functions of soil

• Plant medium

• Recycling system for nutrients

• Animal home

• Engineering medium

• System for water supply and

purification

Classification systems of soil

Criterion: equivalent diameter or

effective diameter of soil particle

Soil texture: gravel >2 mm

sand 0.05~2 mm

silt 0.002~0.05 mm

clay < 0.002 mm

Soil types Soil texture

Clay clay

Loess silt, with small amount of clay and sand

Loam sand, silt, clay

Clay

• Mineral: Al2[(OH)4Si2O5] · nH2O

Al2O3 · 2SiO2 · 2H2O

• poor aeration and drainage

• plastic when wet, when dry become

firm

Clay is only good for paddy rice field.

Loess

• Mineral: most carbonates

small amount of clay minerals

• good aeration, water-holding ability

• easy to be transported by river and

wind

Loess

Loam

• Mixture of clay, silt and sand

• Sandy, plastic when wet

• Easily water contain

• More nutrients than sandy soils

• Ideal fertile soil

Clay- perfect water-holding ability

good for paddy rice field

Both loess and loam can be tillable

soil for most of plants.

But loam is better, because of more

nutrient.

More than 1.5% organic matter

pH value by 6.5

Classification based on

organic matter

• POOR SOIL - <0.5% organic

matter

• INTERMEDIATE - 0.5 to 5%

• RICH - 1.5 to 5%

How does plants get nutrients ?

• Organic & inorganic colloids store vital

water &nutrients.

• Plants feed through the attraction

&exchange of +/- charged chemical

ions.(ca,mg,k)

PROBLEM SOIL

I. Acid soil-

With ph <6.5 and respond to liming.

Low in ca,mg,and with negligable

amount of soluble salts.

Soil appear as brown or reddish

brown,sandy loams or sands.

Not suitable for leguminous plants

Tobacco,potato,cinchona grow well.

….contd….

II. Alkali soil

Formed due to conc. Of exchangeable

sodium & high ph.

Phosphorus is converted to insoluble

forms of calcium phosphate .

Ground nut,sunflower

seeds,cotton,asparagus,pomegranate

grow well.

SOIL TESTING

Objectives-

1.To estimate the available nutrient status,

reaction (acidic,alkaline) of soil.

2.To evaluate the fertility status of soils of

a country/state/district.

3.To prepare a basis for fertilizer , lime or

gypsum recommendation.

Soil testing facilities in kerala

• 14 soil testing labs in kerala i.e.,one for each

district.

• A central soil testing lab at Parottukonam

Nalanchira to supervise,coordinate &control

activities of different labs in state.

• 9 mobile soil testing labs one each in 9 districts

(except Ernakulam, Pathanamthitta, Idukki,

Wayanad,Kasargod)

M SAND

• Manufactured sand

• An alternative to river sand to serve rivers.

• Produced as per Indian standard

specification for base &fine aggregates

code.

• Should be hard,strong,durable,clear &free

from injurious amounts of disintegrated

pieces,alkali,vegetable matter.

SOIL TYPES IN KERALA

There are ten soil groups.1.Red soil

2.Laterite soil

3. Coastal alluvial soil

5.Greyish Onattukara soil

6.Brown hydromorphic soil

7.Hydromorphic saline soil

8.Acidic saline soil

a)Kayal soil

b)Karappadam

c)Kari soil

9. Black soil

10. Forest soil

Soil erosion

Causes

• Water

• Wind

• Lack of Vegetation

Soil contamination

Causes

Presence of man made chemicals

Pesticides

Oil & fuel dumping

Direct discharge of industrial waste &

petroleum hydrocarbons

Lead & other heavy metals

Human excreta

Soil transmitted diseases

• Ascariasis

• Amoebiasis

• Hook worm infestation

Ayurvedic concept

Desa

• Important in collection of drugs.

• Quality of dravya depends on desa

• Plays a major role in rogi pareeksha.

• Knowledge of desa is essential for

treatment.

Caraka samhita

Factors producing disease

common uncommon

air,water,land,time

Types of desa

Determined by the nature of soil.

Three types of bhoomi desa

jangala anupa sadharana

Rough,harsh soil Stable,soft soil Combination of both

Sand content more swampy Combination of both

Bhoomi pareeksha

• Geographical factors like soil

• Panchabhoutika constitution of dravya

depends on that of soil.

• Susruta described six types of bhumi

based on this.

Types of BhoomiMahabhuta Soil Colour Plants

Prithvi Hard ,heavy

with rocks or

stones

Bluish black Big trees

Ap Cool , oily

proximal to

water

Pale Herbs ,grass

Agni Light less

storny

Different Scanty

Anila Dry Ash or light

brown

Small

trees,less juicy

with hollow

trunk

Akasa Porous

,soft,clayey &

level

black Soft wooded

trees

Collection of drug as per soil

• Virechana dravyas- prithvi &jala

predominant soil

• Vamana dravyas - agni & vayu

• Ubhaya bhagahara- both above

• Samana dravyas - akasa predominant

Raja nighantu

Dharanyathi vargam

Synonyms

mruth,mruthika,prashastha,mruthsa,mruth

sna

Types of bhoomi according to

Rajanighantu

1) Kshareeya bhoomi

2) Marubhoomi

3) Jangala desa

4) Krishna bhoomi

5) Pandu bhumi

6) Sharkara or sharakarila bhumi

7) Saikatha or Sikthila bhumi

Bhavaprakash

• Saurastrimrittika-mud/clay from saurastra.

• Krsna mrittika-(black mud)

Cures ulcers,burning sensation

and vitiates kapha and pitta.

Ideal land for drug collection

• Stable &fertile soil

• Sufficiently watered

• Saltless

• Level ground

• Black ,white or red coloured.

Infertile land

• Uneven pits,deep trenches

• Collection of dirty & waste water

• Heaps of ant hills

• Funeral places

• Temples &desert land.

CONCLUSION

• Soil is the most important natural resource

as it supports growth of all plants.

• Ayurveda solely depends on plants for the

treatment .

• As all the properties of medicinal drugs

from various sources are related to soil ,

study of soil becomes essential .