The document is a comprehensive presentation by Dr. B. Victor on soil, covering its definition, composition, functions, and the impacts of soil contamination. It highlights the vital role of soil in agriculture and human life, detailing its properties and the factors influencing plant growth. Additionally, the presentation discusses the causes and effects of soil contamination, along with remedial measures for reducing its impact.

1. Global
contamination
of soil
Presented by
Dr. B. Victor., Ph. D
Email : bonfiliusvictor@gmail.com
Blog: bonvictor.blogspot.com

2. “To forget how to
tend the soils is to
forget ourselves”
-Mahatma Gandhi

3. Presentation outline
 Definition of soil
 Soil-an introduction.
 Human dependence on soil
 Soil functions
 Components, properties, profile, a
nd types of soil.
 Soil contamination-
definition, causes and effects
 Remedial measures
 conclusion

4. Definition of Soil
 Traditional definition – material
which nourishes and supports
growing plants.
 Component definition – mixture of
mineral matter, organic
matter, water and air. (Example:
Loam soil = 45% mineral matter, 5%
organic matter, 25% water, and
25% air).

5. What is soil?
Soil is a biologically
active, complex mixture of
minerals, organic
materials, living organisms, air
and water.

6. Soil-an interface system
Soil is an interface between
biosphere, lithosphere, hydrosphere
and atmosphere.

7. Distribution of land on planet earth
 Land occupies 38% of the total space.
Type of land % composition
Agricultural land ~30 %
Forests ~30 %
Desert 36%
Other land 4%
(rock etc.)

8. Basic Soil constituents
• Solid phase
Mineral matter
Soil is a Organic matter
three •Liquid phase
phase Soil water
system •Gaseous phase
Soil air

9. Human dependence on
soil resource
The site for A place for storing
An essential base
agricultural and raw materials and
of human life
forest production wastes
A mirror of the
A constituent
history of
element of
civilizations and
landscape
cultures.

10. Global degradation of soil
95% of human food is derived
from the earth.
Only 10% of the world’s land
area is suitable for growing crops.
Soil quality is degrading
worldwide.

11. Unique soil functions
An essential natural An integrator of all A medium for plant
resource. parts of ecosystems. growth
A storehouse of
A home for A decomposing
water, heat and
organisms medium for wastes
chemicals.
A buffer system to
A source material for
neutralize harsh
construction of
environmental
shelter
changes

12. Soil-an universal ecological system
A complex heterogeneous medium
A dynamic ecological system
The outer most layer of the earth’s
crust (Earth’s living skin-1/3 of surface).
A complex open process and response
system
A vital resource that provides
food, feed, fuel and fiber

13. An overview of soil functions

14. Major components of soil
• Soils have four major
components:
(1) mineral matter,
(2) organic matter,
(3) air, and
(4) water.
 Mineral matter contains
three
fractions, sand, silt, and
clay.
 Organic matter contains
appreciable quantities
of nitrogen, phosphorus
and sulfur .
 Air and water occupy
the pore spaces in soils.

15. Soil volume
 Soil consists of
organic particles
and inorganic
matter with pore
spaces between
and within them.
 Pore spaces contain
soil air, and soil
solution.
 In other words, soil
volume consists of
solid, liquid
and gaseous
phases.

16. 5-components of soil
Soil component contents/functions
Organic matter -Dead and decaying plants
and animal & animal
manure.
-Add nutrients to the soil &
hold water.-
Minerals Inorganic materials
composed of sand, silt and
clay.
-gives texture to soil.
Living organisms Variety of organisms aerate,
mix and add nutrients to soil.
Water Essential nutrient for plants
Air Provides drainage.

17. Components of soil
by proportion
Organisms 10%
Roots 10%
Humus 80%

18. Mineral particle size ranges
Mineral
sand, silt clay.
matter
Type of mineral Size range
particle
sand 2.0-0.06mm
silt 0.06-0.002mm
clay Less than 0.002mm

19. Soil organic matter
Plant debris, animal
litter carcasses,
excreta
Soluble
leachates Organic compounds
organic matter Bacteria
roots
acetomycetes
fungi
Soil
organisms
algae
protozoa

20. Soil water
(i.e. water in the soil).
 Gravitational
water: Gravitational water
fills all the pore-space, and
leaves no room for oxygen
and gaseous exchange.
 Capillary water: This water
which is held with the force
of surface tension by the
soil particles, and is
resistant to the forces of
gravity.
 Hygroscopic water: This
water is held so tightly (by
surface tension) to the soil
particles that the plant
roots can't take it up.

21. ‘Big picture’ of soil properties
Mineral texture
texture
Organic texture
Micro-aggregates
structure
Macro-aggregates
Micro-porosity
Total porosity Meso-porosity
Macro-porosity
Capillary water
Soil water Gravitational water
Hygroscopic water

22. Physical Properties of Soils
 Soil Texture –the relative proportions
of sand, silt, and clay in the soil.
 e.g. sandy soil, silty soil, and clay soil.
 Soil Structure – Structure refers to the
arrangement of soil particles.
 E.g., Granular, Platy, Wedge, Blocky,
Prismatic, and Columnar.
 Soil structure is of particular
importance in the absorption of
water and the circulation of air

23. Physical properties of soil
Soil texture • Sandy soil, clayey soil, loamy soil
• Granules, crumbs, columns, prisms, blocks, or
Soil structure clusters
Water holding • Depends on texture of soil
capacity • Clay soil holds more water.
• Low pH soils-acidic
Acidity/alkalinity • High pH soils-alkaline
Consistence • Hard, loose, friable, firm, plastic and sticky
color • Dark, yellow, grey hues

24. Soil Color
 Color in soils is due primarily to two
factors, humus content and the chemical
nature of the iron compounds.
Chemical
Humus nature of
content the iron Soil color
compounds
 Humus has a dark brown or black color.
 Iron is an important color material which
stains mineral particles
 Ferrous oxide gives gray color
 Ferric oxide gives red color
 Hydrated ferric oxide gives yellow color

25. Soil profile
Horizon contents
O horizon Fungi, animal wastes,
leaves and branches,
at various levels of
decomposition.
A Horizon(Topsoil) Partially
decomposed matter
B Horizon(Subsoil) Few organisms
Less organic matter
C Horizon partly weathered or
decomposed rock.
R Horizon the solid rock layer

26. Soil pH
 Soil pH is primarily controlled by the
concentration of free hydrogen
ions in the soil matrix.
 Acidic soils have a relatively large
concentration of hydrogen ions.
 Alkaline soils have a relatively low
concentration of hydrogen ions.

27. pH and soil fertility
Soil fertility • Soil fertility is directly influenced by pH
through the solubility of many nutrients.
• At low pH, many nutrients become very
Low pH soluble and are readily leached from the
soil profile
High pH • At high pH, nutrients become insoluble
and plants cannot readily extract them.
Optimum • Maximum soil fertility occurs in the range
pH 6.0 to 7.2

28. Soil Types
Depending on the size of the
particles in the soil, it can be
classified as:
Sandy soil
Silty soil
Clay soil
Loamy soil
Peaty soil
Chalky soil

29. Soil factors influencing plant growth

30. Soil organisms
Micro-biota
• Soil algae, bacteria, fungi, protozoans
Meso-biota
• Nematodes, oligochaetes, insect
larvae, collembola.
Macro-biota
• Earth worms, rats, snakes.

31. Dependence biota on soil
Soil biota depend on
the soil environment
for their energy and
nutrient supply.

32. Soil contamination
Soil contamination is the
presence of man-made
chemicals or other
alteration to the natural
soil environment.

33. The fate of contaminants in soil
Contaminants bind
tightly to the soil
Contaminants
evaporate into the air
Contaminants end up
in soil/ground water.

34. Common chemicals of
soil contamination
Petroleum
Heavy metals
hydrocarbons
Pesticides Solvents

35. Sources of soil contaminants
Industrial • Active mines
pollution • Solid wastes, waste waters
• Consumption of fossil
Oil pollution fuels.
Agricultural
• Pesticides, fertilizers
pollution

36. Land pollution: sources of
solid wastes
 Wastes from agriculture – crop and farm
residues, anima manure.
 Wastes from mining – coal wastes, metal ore
wastes.
 Industrial wastes- solvents chemicals, paints.
 Solids from sewage treatments-biomass
sludge, settled solids.
 Ashes – residues from solid fuels
 Carbage –
glass, metals, clothes, plastics, wood, papers.

37. Causes of soil contamination
Indiscriminate use of fertilizers
Indiscriminate use of
pesticides, insecticides and herbicides.
Dumping of solid wastes
Deforestation and soil erosion
Urbanization

38. Effects of soil contamination

39. Effects on agriculture
 Reduced soil fertility
 Low crop yield
 Reduced soil biodiversity
 Reduced nitrogen fixation

40. Human health effects
Exposure to
• Nervous system disorders,
heavy metals kidney damage, liver toxicity.
in soil
Exposure to
agricultural • Cancer, infertility
chemicals
Other
• Birth defects, nervous system
industrial disorders, kidney diseases.
toxins

41. Reducing soil contamination
 Reduce use of herbicides and pesticides
 Encourage organic farming.
 Dispose garbage properly.
 Recycle garbage.
 Avoid over packaged items.
 Utilize natural resources efficiently and
reduce wastage.

42.  Dr.B.Victor is a highly experienced
professor, recently retired from the reputed
educational institution- St. Xavier’ s
College, Palayamkottai, India-627001.
 He was the dean of sciences, IQAC coordinator
and assistant controller of examinations.
 He has more than 32 years of teaching and
research experience
 He has taught a diversity of courses and guided
12 Ph.D scholars.
 send your comments to :
bonfiliusvictor@gmail.com

43. Thank you for watching