SOIL

Fundamental Concepts

Professor & Head,Department of Soil Science and Agricultural Chemistry

College of Agriculture, Vellayani

Dr. N. Saifudeen

What is soil?

Dirt

Filth

Land

Earth

o Dirt is what you find under your fingernails.

o Soil is what you find under your feet.

What is soil?

What’s the

difference between

soil and dirt?

Think of soil as a

thin living skinthat covers the land on earth’s crust

Soil is an amazing substance!!

Air 25%

Mineral Matter

45%

Water 25%

Organic Matter 5%

SOILComponent definition:

A complex mixture of mineral matter, organic matter,

water, and air.

and countless organisms.

Without life, there is no soil.

Living things haven't just made a home in the

soil on our planet.

Life actually made the soil as we know it.

o Those planets have plenty of rocks.

o Mars has windstorms that erode rocks into dust.

o Venus has an acid atmosphere that cooks rocks into

new chemicals.

o But there's still something missing…

oLife…….

There is no soil on Mars or Venus or Moon

How come?

Soil

o Soft

o Natural body

o Sustaining life (including plant growth)

o Dynamically changing

o At the earth surface

SOIL PROFILES

Dig down deep into any soil, and you’ll see that it is made of layers, or horizons.

Put the horizons together, and they form a soil profile.

Like a biography, each profile tells a story about the life of a soil.

Soil is the Basis of the Ecosystem

The living systems

occurring above and

below the ground

surface are determined

by the properties of the

soil. We often ignore the

soil because it is hard to

observe.

Soils Perform Vital Functions

Sustaining plant and animal life

below and above the surface

Regulating and partitioning

water and solute flow

Filtering, degrading,

immobilizing, and detoxifying

Storing and cycling

nutrients

Providing support

to structures

Rain

RunoffSoil

Infiltration

Soils Support Life

Organism Types

bacteria

fungi

protozoa

nematodes

arthropods

earthworms

Roles & Benefits

decomposition

release nutrients

create pores

stabilize soils

Definitions, Byers, et al., Formation of Soil, 1938*

o Soils are natural media for the growth of plants.

They are mixtures of fragmented and partly or

wholly weathered rocks and minerals, organic

matter, water, and air, in greatly varying

proportions, and have more or less distinct layers or

horizons developed under the influence of climate

and living organisms…Soils are dynamic in

character …the product of the action of climate and

living organisms upon the parent material, as

conditioned by the local relief.

o *Yearbook of Agriculture

Definitions, Hillel, Introduction to Soil Physics, 1982

o The soil is a heterogeneous, polyphasic,

particulate, disperse, and porous system, in

which the interfacial area per unit volume can be

very large. The disperse nature of the soil and its

consequent interfacial activity give rise to such

phenomena as adsorption of water and

chemicals, ion exchange, adhesion, swelling and

shrinking, dispersion and flocculation, and

capillarity.

Definitions, Spangler & Handy, 1982, Soil Engineering

o Soils are natural materials which occur in infinite

variety over the earth and whose engineering

properties may vary widely from place to place

within the relatively small confines of a single

engineering project …

o The properties of soils are continuously changing as

the amount of moisture fluctuates and other

environmental influences vary… and may change

dramatically under load

o Soil is used as construction material …

Definition, Soil Science Glossary, SSSA

(ii) The unconsolidated mineral or organic matter on

the surface of the earth that has been subjected to

and shows effects of genetic and environmental

factors of: climate (including water and

temperature effects), and macro- and

microorganisms, conditioned by relief, acting on

parent material over a period of time. A product-

soil differs from the material from which it is

derived in many physical, chemical, biological,

and morphological properties and characteristics.

Soil FormationFive factors that affect soil formation

Parent Material

Climate

Living Organisms

Relief (Topography)

Time

Parent Material

Igneous sedimentarymetamorphic

ROCKS

WeatheringBreaks down rocks to create Parent Material

It can be caused by Climate, water, or living things

Movementof sediment and rock to new places.

1. Physical weathering

The effects of climatic factors such as temperature,water,

and wind. Freezing and thawing are a major contributor.

Weathering is continuous

2. Chemical weathering

a. changes the chemical makeup of rock and

breaks it down. Rainwater can dissolve

minerals.

b. Some minerals react with oxygen. Oxidation

further decomposes rock.

Weathering (cont.)

B. Weathering causes soil to:

1. Develop

2. Mature

3. Age

Soil Forming Processes

o Translocations

o Transformations

o Additions

o Losses

SOIL

o As a portion of the landscape: Collection of

natural bodies occupying portions of the earth’s

surface that support plants and that have properties

due to the integrated effect of climate and living

matter, acting upon parent material, as conditioned

by relief, over periods of time.

Soils Sustain Life

Soils Support Urban Life

Soils Support Agriculture

Soils Clean and Capture Water

Soils Support Buildings/Infrastructure

Soils Support Recreation

Soils are Living

Soils Support Health

Soils Protect the Natural Environment

Soils and the Products We Use

Soils and Climate

Soils, Culture, and People

Value of Soils

to our natural environment and society

Soils Support

Food Production….

We wanted

Green

Revolution

Food, Forest and Population….

Soil Management Affects Soil Quality

Soil Quality

Soil Test Kit

Why do we study soil?

What is the role of

Soil Science?

Decreasing capacity of natural resources

o Study of soil as a part of terrestrial ecosystem, environment, and integrated Earth surface System;

o Study of soil by physical, chemical and biological means and others;

o Study of soil in scales ranging from molecular to pedosphere;

o Study of soil in interaction with water, air, biomes, and humans, etc.

What is Soil Science?

Soil Science

o Soil - plant science: - ion uptake, soil fertility,

nutrient transport, bioavailability; food quality

o Soil-water science: water translocation, water

use efficiency; nutrient loading, drinking water quality

o Soil- air science: gas exchange, emissions,

GHG, Global change

o Soil – material science: soil mechanics or

dynamics, soil engineering;

Soil Scienceo Soil – ecosystem science: soil ecosystems,

stability of ecosystem. Biodiversity and ecological safety

o Soil - landscape science: soil associations, land

use patterns, soil taxonomy, archeology ,etc

o Food Science and Nutrition

o Medicine & Health science:

o Archaeology

Role of Soil Science

o Basic discipline of natural sciences;

o Fundamental science of agricultural

sciences;

o Core science of environmental and

ecological sciences;

Role of Soil Science

Impacts in:

o Land use planning;

o Help solve food supply,

o Policy making - agriculture and environment protection;

o Consultancy: standards, restrictions, etc.

What is soil?

Definition, Joffe, 1949, modified by Birkeland, 1999

o Soil is a natural body consisting of layers

(horizons) of mineral and/or organic

constituents of variable thicknesses,

which differ from the parent materials in

their morphological, physical, chemical,

and mineralogical properties and their

biological characteristics.

Definition, Soil Taxonomy, 2nd ed.

o Soil is a natural body comprised of solids

(minerals and organic matter), liquid, and gases

that occurs on the land surface, occupies space,

and is characterized by horizons, or layers, that

are distinguishable from the initial material as a

result of additions, losses, transfers, and

transformations of energy and matter or the ability

to support rooted plants in a natural environment.

A soil survey includes maps, descriptions, properties,

climate, and interpretations.

These are excellent sources of information

Soil Survey is a Scientifically-Based Inventory

Scientific Names for Soils Reduce Ambiguity

• Like plants and animals, soils are classified

• The system is called Soil Taxonomy

• The highest level is the soil order (12)

• The lowest level is the soil series, often a

place name

Soil Order Formative terms

Alfisols Alf from combination of al (aluminum) and f (ferrous) iron

Andisols Ando from Japanese term dark referring to dark volcanic ash

Aridisols Latin, aridies, dry arid

Entisols Ent meaningless, root recent

Gelisols Latin gelare, to freeze

Histosols Greek, histos, tissue

Inceptisols Latin, incepum, beginning, inception

Mollisols Latin, mollis, soft, mollify

Oxisols French oxide

Spodosols Greek spodos, wood ash

Ultisols Latin ultimus, last, ultimate

Vertisols Latin verto, vertical cracking

Gelisols: Frozen

Histosols: Organic, wet

Spodosols: Sandy, acidic

Andisols: Volcanic ash

Oxisols: Very weathered

Vertisols: Shrink and swell

Aridisols: Very dry

Ultisols: Weathered

Mollisols: Deep, fertile

Alfisols: Moderately weathered

Inceptisols: Slightly developed (young)

Entisols: Newly formed

The 12 soil orders in the

Soil Taxonomy system

The Unique Resource Base

Warm, humid, tropical region

High solar radiation, 365days

High rainfall (300 cm)

High biological activity and rich

biodiversity

Undulating topography

Altitude 3-5m bmsl to 2500 m amsl

Distinct climatic changes

5% water resources of India

Kerala State

COASTAL SANDY SOILS

Kadinamkulam series: Mixed, isohyperthermic Typic Ustipsamments

SOUTHERN LATERITEKalliyur, Thiruvananthapuram

Clayey, kaolinitic, isohyperthermic, Typic Kandiustult

NORTHERN LATERITES

HIGH HILLS

World Soil Day 2014: “Soils, foundation for family farming”

World Soil Day 2015: “Soils, a solid ground for life”

5 December

http://www.fao.org/globalsoilpartnership/iys-2015/en/

http://ec.europa.eu/environment/soil/scoping_en.htm

nsaifudeen@gmail.com