The document summarizes key information about soil resources. It defines soil and discusses soil-forming factors such as parent material, climate, topography and organisms. It also describes soil composition, nutrients, horizons, texture, characteristics, types of fertilizers and their pros and cons. Methods to prevent soil erosion, salinization, desertification and reclaim degraded land are also summarized.

1. Soil Resources
Submission by: Ankit Chhabra
Roll No: 01315603615
Project Guide: Dr. Tanuja Nautiyal
Department of Chemistry
Northern India Engineering College New Delhi

3. Read dust storm in china and measures taken to control it
Millions of trees defend
China against raging dust
storms from the Gobi
desert. Shown are pines
and poplars developed by
Chinese scientists to
grow rapidly in poor soil.
The agricultural land is
protected by the Great
Green Wall.

4. 1)The unconsolidated organic and mineral material
on the earth’s surface that is capable of
supporting plants.
2)A dynamic natural body, in which plants grow,
that is composed of mineral and organic materials
and living organisms.
Soil Definitions

5. Soil-Forming Factors
 Parent material (rock that is slowly broken down by
biological, chemical, and physical weathering
processes in nature.)
 Climate (when temperatures are below freezing
decomposition of organic matter and water
movement are slow, soil dvelopment in the humid
tropics is accelerated by the rapid weathering of rock
and soil minerals, the leaching of nutrients, and the
decompostion of organic detritus.)precipitation and
temperature changes

6. Soil-Forming Factors
 Topography (presence or absence of mountains and
valleys, steep slopes have little or no soil on them
because soil and rock are continually transported down
the slopes by gravity; moderate slopes and valleys, may
encourage the formation of deep soils)
 Organisms (plant roots, lichens produce acids, animals
that burrow or tunnel, such as earthworms, voles, mix
the soil, distributing organic and mineral matter
 Time Grasslands soil have rich organic matter
 How long climate has been altering parent material over
geologic time

7. Soil Composition
Soil Composition
• 45% Mineral particles (broken down pieces of rock)
• 5% Organic matter (humus - from dead organisms,
worm castings, leaf litter)
• 25% Water (precipitation)
• 25% Air (More with sandy soil, less with clay soil)

8. Soil Composition
Soil organisms - Millions in one teaspoon of fertile
agricultural soil! bacteria, fungi, algae, microscopic
worms.
•provide ecological services such as worm castings,
•decomposition to humus,
•breaking down of toxic materials,
•cleansing water,
•nutrient cycling from decomposers or upon death

9. Soil Nutrients (NPK)
Organic - animal manure, bone meal, compost
(slow-acting, long-lasting)
•Delay in availability to plants, needs time for the organic
material to decompose
•Delay causes low level of nutrient leaching
•Improves water holding capacity

10. Soil Nutrients (NPK)
Inorganic - Manufactured from chemical
compounds (fast-acting, short-lasting)
•Highly soluble so immediately available to plants
•High solubility also makes it leach quickly (pollutes water)
•Suppresses growth of microorganisms
•Source of nitrogen gases that increase air pollution
•Production requires much energy from fossil fuels,
increasing CO2 emissions.

11. Soil Horizons

12. Soil horizon
 O Horizon: Organic or litter layer, topmost layer
 A Horizon: Topsoil; mostly inorganic minerals with some
organic material and humus mixed in; crucial for plant growth
 E Horizon: Eluviation horizon; loss of minerals by leaching, a
process whereby solid materials are dissolved and transported
away, only found in forested areas, light colored
 B Horizon: Subsoil; zone of accumulation or deposition of
leached minerals and organic acids from above, clay and
minerals, (iron, aluminum and calcium)
 C Horizon: Slightly altered parent material
 R Horizon: Bedrock

13. Soil Organisms

14. Soil organisms
•Ants live in the soil in enormous
numbers, constructing tunnels
•and chambers that aerate it.
•Food brought in by the ants and the
left Over is eventually decomposed
and add to the organic matter in the
• soil.
•Ants also bury seeds in the soil and
help in reproduction

15. Soil organisms
•Symbiotic association between the
roots of plants and fungi.
•When mycorrhizal fungi are absent
from the soil, the reestablishment of
certain tree species is retarded.

16. Nutrient Cycling
•Leaching causes some nutrient minerals to be lost from
the soil ecosystem to groundwater, the weathering of the
parent material replaces much or all of them.
•Dusts carried in the atmosphere help replace nutrient
minerals in certain soils.
•Hawaiian rainforest soils, for example, receive dust
inputs from central Asia, a distance more than 600km
away.

17. Nutrient Cycling

18. Soil characterization
 Soil can be characterized by color and several other
traits:
• Texture
• Structure
• pH

19. Soil Texture
 Determined by size of particles
 Three main categories:
Clay = particles < 0.002 mm diameter
Silt = particles 0.002–0.05 mm diameter
Sand = particles 0.05–2.0 mm diameter

20. Soil Texture
 Best for plant growth is loam, an even mix of these
three types.

21. Loam
 Is an ideal agricultural soil. Has an optimum
combination of different soil particle sizes. It
contains 40% each of sand and silt, and about 20%
of clay.
 Generally larger particles provide structural support,
aeration, and permeability to the soil, whereas
smaller particles bind into aggregates, or clumps,
and hold nutrients and water.

22. Loam
 Sandy soil is not desirable because they do not hold
mineral or water and plants grown in such soils are
more susceptible to mineral deficiencies and
drought.
 Clayey soil provide poor drainage and often do not
contain enough oxygen.

23. Soil Texture Chart
 It is possible find the type of soil by making use of
the soil texture chart.
 We can determine the percentage of each
component in a soil sample and then plot the results.
(make sure the sum of the sand plus silt plus clay will
always be 100 percent.

25. Soil Characteristics
Understand what soil is and how it forms.
•1) clay = “layer silicates that are formed as
products of chemical weathering of other silicate
minerals at the earth's surface. They are found
most often in shales, the most common type of
sedimentary rock.”
•2) silt = rock worn into tiny pieces (coarser than
clay, but finer than sand). usually 1/20 millimeter
or less in diameter

26. Soil Characteristics
•3) sand = quartz or silica worn down over time.
grains with diameters between 0.06 mm to 2 mm
•4) organic matter (humus)
•5) Loam = soil containing a mixture of clay, sand,
silt and humus. Good for growing most crops.

27. Soil pH
 Most soil ranges from 4 to 8
 The soil of the Pygmy forest in Mendocino County,
California, is acidic, with a pH of 2.8 to 3.9
 Soils in Death Valley, California, have a pH of 10.5
 At a low pH, the aluminum and manganese in soil water
are more soluble, and the roots absorb them in toxic
concentrations.
 Certain mineral salts essential for plant growth, such as
calcium phosphate, become less soluble and less
available to plant at a higher pH.
 An acidic soil has a relatively reduced ability to bind
postiviely charged ions to it.

28. Soil Porosity and Permeability
 Porosity - volume of water that “fits between” the soil particles
 Permeability - rate of flow of water through soil
 % retention - how much water is “trapped” by soil
 Porosity and Permeability are directly related; when one is
high, the other is high as well. % water retention is inversely
related to both.

29. Soil Porosity and Permeability
• 1) Clay -  porosity  permeability,  retention
• 2) Silt -  porosity,  permeability, retention
• 3) Sand -  porosity,  permeability,  retention
• 4) Organic matter -  porosity,  permeability, 
retention

30. Alfisol
 Brown to gray-brown A-horizon
 Moderately weathered forest soils
 Found: Moist temperate forest biomes
 Most organic material is found in living plants
 Adequate for agriculture if supplemented with
fertilizer or organic material

31. Mollisols
 Primarily found in temperate, semiarid grasslands
 Fertile soils
 Dark brown to black A –horizon rich in humus
 Soluble minerals remain in the upper layers because
precipitation is not great enough to leach them into
lower layers.
 Best agricultural soil
 Most of the world’s grain crops are grown in
mollisols.

32. Aridisols
 Thin light colored and contain a lot of sand.
 Found: Dry lands and deserts
 Susceptible to salinization
 Crops can be grown on aridisols, if water is supplied
by irrigation

33. Oxisols
 Low in nutrient minerals
 Exist in tropical and subtropical areas with ample
precipitation
 Little organic material accumulates on the forest
floor (O-hroizon) because leaves and twigs are
rapidly decomposed.
 A-horizon is rich with humus
 Most organic matter is found in living plants

34. Soil Erosion
 Wind, water, ice, and other agents promote soil erosion
 Rainfall loosens soil particles, and then transported by
moving water.
Effects of soil erosion
 Reduces the amount of soil in an area and limits the
growth of plants
 Causes a soil to lose its fertility because essential nutrient
mineral and organic matter in the soil are removed.
Leads to loss of productivity of crops and use of more
fertilizers
 Sediments that gets into water bodies affect water quality
and fish habitats.
 Sediments with pesticides add to pollution

35. Cause and prevention of soil erosion
 Poor soil management practices
 Poor agricultural practices
 Removal of natural plant communities
 Unsound logging practices
 Clearcutting large forested areas
Sufficient plant cover limits the amount of soil erosion.
Roots help to hold the soil in place.

36. Nutrient mineral depletion
 As plant and animal detritus decomposes innatural
ecosystems, nutrient minerals are cycled back to the
soil for reuse. In agriculture, much of the plant
material is harvested. Because the nutrient minerals
in the harvested portions are unavailable to the soil,
the nutrient cycle is broken, and fertilizer must be
added periodically to the soil.

37. Soil Salinization
 The gradual accumulation of salt in a soil, often as a
result of improper irrigation methods.
 Irrigation water contains small amounts of dissolved
salts. The continued application of such water, leads to
the gradual accumulation of salt in the soil.
 When the water evaporates, the salts are left behind,
particularly in the upper layers of the soil, which are the
layers important for agriculture.
 The level can get high to an extent that plants can get
poisoned or their roots get dehydrated.
 When soil is waterlogged , capillary movement may carry
salts from groundwater to the soil surface, where they are
deposited as a crust of salt.

38. Salinization & Waterlogging

39. Salinization & Waterlogging

40. Desertification

41. Desertification
 Asia and Africa the largest land areas with
extensive soil damage, and rapid population
growth is the main cause.
 Prolonged periods of drought (Sahel). During
droughts the soil cannot support crop or
grazing animals. The Sahelians must use the
land to grow crops or they will starve.
Overexploitation leds to desertification
 To reclaim the land would require restricting
its use for many years so it could recover.

42. Soil conservationand Regeneration
 Conservation tillage
 Crop rotation
 Contour plowing
 Strip cropping
 Terracing
 Shelterbelts

43. Preserving Soil Fertility
List and describe some of the pros and cons of
using fertilizers. What different sorts of
fertilizers are available?
Experimental data comparing methods!
Click on the picture!

44. Organic and Inorganic Fertilizers
 Organic fertilizers include natural materials as
animal manure, crop residues, and compost. They
are complex and their exact composition vary. The
nutrient minerals in the organic fertilizers become
available to plants only as the organic material
decomposes. They are slow-acting and long-lasting
 Inorganic fertilizers are manufactured from chemical
compounds and their exact composition are known.
They are immediately available to plants . They also
quickly leach away.

45. Soil Reclamation
 Stabilizing the land to prevent further erosion
 Restoring the soil to its former fertility
 To stabilize the land, the bare ground is seeded with
plants that eventually grow to cover the soil, holding it in
place. After the Dust Bowl, land in Oklahoma and Texas
was seeded with drought-resistant native grasses.
 Plant shelterbelts to lessen the impact of wind ( a row of
trees planted as a windbreak to reduce soil erosion of
agricultural land.
 Restoration of soil fertility to its original level is a slow
process. Use of the land must be restricted it cannot be
farmed or grazed

46. Thank You
Submission by: Ankit Chhabra
Roll No: 01315603615
Project Guide: Dr. Tanuja Nautiyal
Department of Chemistry
Northern India Engineering College New Delhi