A short lecture on the Bio-Physical- and chemical properties of soil which includes the nutrient cycling process

1. Presented by:
Janine V. Samelo

2. COLOR
TEXTURE
STRUCTURE
DENSITY
CONSISTENCE
Physical Characteristics
of the soil

3. Soil Texture

4. Soil Textural Triangle
Foth, 1990

5. Soil Texture
SIZE AND DISTRIBUTION OF PARTICLES
 Silt Loam- has a broken appearance, appears
cloddy, lumps can be broken readily; when
pulverized, it feels soft and floury.
 Clay Loam- breaks into clods or lumps that are
hard when dry, does not crumble readily but
works into a heavy compact mass.
 Clay- fine-textured soil that usually forms very
hard lumps or clods when dry, usually sticky
when wet, individual grains can be seen or felt
readily.

6. Soil Texture
 Sand -loose and single-grained, individual grains
can be seen or felt readily, when moist, it
forms a cast but crumbles when touched.
 Sandy Loam-high percentage of sand but having
enough silt and clay to make it somewhat
coherent, If squeezed when moist, a cast can
be formed without breaking readily
 Loam.- A loam is soil having a relatively even
mixture of different grades of sand, silt, and
clay. Squeezed when dry, it forms a cast which
can be handled freely without breaking.

7. EFFECT OF SOIL TEXTURE
ON
ROOT PENETRATION
FIGURE: Development of
root system of a yellow
birch seedling in sand an
loam soil. Both soils had
adequate supplies of water
and oxygen. (Redmond,
1954)

8. The arrangement and
organization of soil particles
into natural units of aggregation
called peds.
Soil Structure

9. Soil Structure
Foth, (1990)

10. Soil Structure

11.  influences the rate at which
water and air enter and move
through the soil
 affects root penetration and
the nutrient supply of the soil
Soil Structure

12. EFFECT OF SOIL STRUCTURE
ON DOWNWARD MOVEMENT
OF WATER

13. Soil Porosity
 Soil porosity is affected mostly by
soil aggregation, texture, root
activity, entrapped gases, and by
burrowing insects, worms, and other
animals.
 The structure as well as the porosity
of the soil is extremely vital for the
reduction of the risk of soil erosion
and increase the water infiltration.

14. Soil Porosity
 Clay- poor soil aeration when wet
 Sands- good aeration or gaseous
diffusion
 50% porosity is desirable, good
balance between the retention of
water for plant use and an oxygen
supply for root respiration.

15.  Consistence is the resistance of
the soil to deformation or
rupture.
 determined by the cohesive and
adhesive properties of the
entire soil mass.
Soil Consistence

16.  deals with the strength and nature
of the forces between the sand,
silt, and clay particles
 important for tillage and traffic
considerations.
 Clay soils can become sticky when
wet, and thus make hoeing or
plowing difficult.
Soil Consistence

17. Tilth
 physical condition of the soil that
refers to the ease of tillage.
 depends on the degree and
stability of soil aggregates.
 refers as fitness of soil as a
seedbed,
 desirability for seedling emergence
and root penetration.

18. SOIL Erosion
Reasons:
• Insufficient
vegetative cover
• Growing crops on
non-suitable soils
for cultivation
• Improper tillage
How to reduce:
• Using soil to produce
crop w/c it is
suitable
• Using adequate
fertilizer and lime
• Use proven soil
preparation and
tillage methods

19. SOIL COMPACTION
 The changes in soil porosity, owing
to compaction are caused by the
long-term effects of cropping and
tillage and by the pressure of
tractor tires, animal hooves, and
shoes

20. Results of SOIL COMPACTION
decrease in total pore space
decrease in macropore space
increase in micropore space.

21. Soil Organisms & Soil
Health
Brady & Weil, 2002

22. Soil Organisms & Soil
Health
Brady & Weil, 2002

23. Bacteria
Single celled
A gram of fertile soil commonly
contains 10' to 10 10 bacteria.
Most are heterotrophs
Most are aerobes and require a
supply of oxygen
Some are anaerobic

24. Fungi
heterotrophs that vary greatly in size
and structure.
Mold mycelia are commonly seen
growing on bread, clothing, or leather
goods.
Rhizopus is a common mold that grows
on bread and in soil.
Their tolerance for acidity makes them
particularly important in acidic forest
soils.

25. Nematodes
Roundworms
most abundant animals in soils.
round shaped
free-living and inhabit the water films
that surround soil particles.
can be grouped into those that feed
on: (1) dead and decaying organic
matter, (2) living roots, and (3) other
living organisms as predators.

26. Arthropods
have an exoskeleton and jointed legs
have heart and blood system, and
usually
a developed nervous system.
most abundant are mites and
springtails.
include spiders, insects millipedes,
centipedes, wood lice, snails, and
slugs.

27. The Role of Organisms in
Soil Health
Aids in the decomposition of organic
matter (bacteria & fungi)
Releases compounds which are accumulated in
the deeper layer of soil as minerals and are
carried by underground water as nutrients
absorbed by plants
Assists nutrient cycle and release of
energy as heat

28. The Role of Organisms in
Soil Health
Breaking of aggreggates
Aids in the penetration of water
Aids in the development of porosity
Burrowing animals entraps gases for aeration

29. Essential Macronutrients
in Soil

30. ♣ exchange of nutrient elements
between the living and non
living parts of the ecosystem.
♣ conserves the nutrient supply
and results in repeated use of
the nutrients in an ecosystem.
NUTRIENT CYCLES

31. ♣ Mineralization
♣ Immobilization
NUTRIENT CYCLING
PROCESS
conversion of the elements in organic matter into
mineral or ionic forms such as NH3 , Cat-, H2P04 -
, S04 2- , and K+.
uptake of inorganic elements (nutrients) from the
soil by organisms and conversion of the elements
into microbial and plant tissues. These nutrients
are used for growth and are incorporated into
organic matter.

32. WATER CYCLE

33. CARBON CYCLE
Gaur, (20008)

34. CARBON CYCLE
Thru photosynthesis
(biotic)
Thru rocks, soil and
oceans (abiotic)

35. NITROGEN CYCLE
FOTH (1990)

36. NITROGEN FIXATION
Biological
Industrial
Atmospheric
• fixed by lightning
and other ionizing
phenomena of the
upper atmosphere
• converted as HNO3
• added to soils in
precipitation
• Via Haber-Bosch
process
• Via nitrogen fixing
bacteria (legumes)
symbiotic Non-symbiotic
• blue
green
algae

37. NITROGEN FIXATION
Adapted from Foth (1990)

38. NITROGEN CYCLE
 Nitrification is the biological oxidation of
ammonium (NH4') to nitrite (N02 ) and to
nitrate (N03- )
 two-step process, with nitrite (NO 2-) as the
intermediate product.

39. NITROGEN CYCLE
FOTH (1990)

40. PHOSPHORUS
Most phosphorus occurs in the mineral
apatite in igneous rocks and soil parent
materials.
Fluorapatite (𝐶𝑎10 𝑃𝑂4)6 𝐹2 is the most
common apatite mineral.
Phosphorus plays an indispensable
role as a universal fuel for all
biochemical activity in living cells.
Sedimentary nutrient cycle-> SLOW

41. PHOSPHORUS CYCLE
Adapted from Foth (1990)

42. PHOSPHORUS CYCLE
Adapted from Foth (1990)

43. PHOSPHORUS CYCLE
 The potential for P fixation tends to
maintain phosphorus in insoluble forms
and, therefore, the phosphorus
concentration in the soil solution is very
low.
 Thus, mass flow cannot supply plants with
sufficient phosphorus except in unusual
cases.
 As a result, most of the H 2PO4 - at root
surfaces has been moved there by
diffusion.

44. POTASSIUM CYCLE
Adapted from Foth (1990)

45. POTASSIUM CYCLE
 When plants are dormant and leaching is minimal,
weathering of potassium minerals results in an
increase in solution potassium, followed by an
increase of exchangeable potassium, followed by an
increase in the amount of fixed potassium.
 Weathering and subsequent loss of potassium by
leaching with time can deplete the soil of potassium
minerals and create soils with few potassium
minerals and very low available potassium.
 This is generally true for intensively weathered soils.
 Potassium does not complex with organic compounds

46.  Sulfur exists in some soil minerals, including
gypsum (CaSO4-2H20).
 Mineral weathering releases the sulfur as
sulfate ion which is absorbed by roots and
microorganisms.
 released as sulfur dioxide (SO2) into the
atmosphere by the burning of fossil fuels
 accumulates in soils as organic sulfur in plant
residues and is then mineralized to S04 2 -.
 Plants may absorb sulfur in the air through leaf
stomates.
SULFUR CYCLE

47. SULFUR CYCLE
Gaur (2008)

48.  contributes to the development of soil acidity.
 Sulfate is adsorbed onto the surfaces of iron
and aluminum oxides and onto the edges of
silicate clays, where aluminum is located.
 Critical to formation and fumction of protein
 Found in soil as SOM
SULFUR

49. MAGNESIUM
 Magnesium is a constituent of chlorophyll.
 magnesium deficiency results in a
characteristic discoloration of leaves.
 Sometimes, a premature defoliation of the
plant results. The chlorosis of tobacco,
known as sand drown, is due to magnesium
deficiency.
 Cotton plants suffering from a lack of
magnesium produce purplish-red-colored
leaves with green Veins.

50. CALCIUM CYCLING
Adapted from Foth (1990)

51. WHY STUDY pH?
Nutrient Availability
Effect on soil Organisms
Toxicities in acid soils
pH preferenes of plants

52. SOIL ACIDITY
W.L. Daniels

53. SOIL ACIDITY
W.L. Daniels

54. pH and Nutrient
Availability
 Foth, (1990)

55. Why Soils are acidic
Rainfall and leaching
Acidic parent material
Organic matter decay
Harvest of high yielding crops

56. 1) In all soils respiration by roots and
other soil organisms produces carbon
dioxide that reacts with water to form
carbonic acid (H2CO3). This is a weak
acid, which contributes H+ to the soil
solution
Sources of Soil Acidity
𝐶𝑂2 + 𝐻2 𝑂 → 𝐻2 𝐶𝑂3

57. 2) the mineralized nitrogen and sulfur
from the organic matter are oxidized
to nitric and sulfuric acid
3) natural or normal precipitation
reacts with carbon dioxide of the
atmosphere and the carbonic acid
formed gives natural precipitation a
pH of about 5.6.
Sources of Soil Acidity

58. Soil Acidity Management
Agricultural lime- Soil amendment containing CaCO3,
MgCO3 used to neutralize soil acidity

59. CONCLUSION
Soils has bio-physico and chemical
properties
 Soil physical structure ad texture
influences the rate at which water and
air enter and move through the soil
 affects root penetration and the nutrient
supply of the soil
 Soil organisms play a major role in
formation of soils and in nutrient cycling

60. CONCLUSION
 Living organisms need many
nutrients to survive. Vast cycles
makes nutrients available for reuse
by transforming and circulating them
thru the atmosphere, hydrosphere,
lithosphere and biosphere
 Soil pH is needed for managing
nutrient availability, effect on soil
Organisms, toxicities in acid soils,
preferences of plants

61. REFERENCES
Alberto, A.M.P., (2006). Basic Ecology. (2nd ed) Nueva Ecija: CLSU CERDS
Albers, C., Fenton M., & Ketterings Q. (2008) Cornell University Agronomy Fact Sheet
series: Retrieved August 29, 2016 from
nmsp.css.cornell.edu/publications/factsheets.asp.
Allaby, M. (2000). Basics of Environmental Science. (2nd Ed) London: Taylor & Francis e-
Library
Bharucha, E. (2004). Environmental Studies: Undergraduate Courses of all branches of
higher education (Dunster, C. & Patel B., Eds). University Grants Commission New Delhi
Chauhan A, Mittu B (2015) Soil Health - An Issue of Concern for Environment and
Agriculture. J Bioremed Biodeg 6: 286. doi:10.4172/2155-6199.1000286
Daniels, W. L. Basic Soil Science. Retrieved August 29, 2016 from
http://pubs.ext.vt.edu/430/430-350/430-350_pdf.pdf &
http://www.cses.vt.edu/revegetation/
Foth, H. D. (1990). Fundamentals of Soil Science. (8th Ed). United States of America:
John Wiley & Sons.

62. REFERENCES
Gaur, R. C. (2008). Basic Environmental Engineering. New Delhi, India: New Age International (P)
Ltd, Publishers
JOHNSON, G. V., W. R. RAUN, H.N ZHANG, and J. A. HATTEY. 2000.Oklhoma soil fertility
handbook, Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK
74078
Lehman, R. M., et al. (2015). Soil Biology for Resilient, Healthy Soil. Journal of Soil and Water
Conservation 70 (1):12A-18A
Prasadini P., & Lakshmi G. S. Environmental Science BIRM 301 Study Material. Dept. of
Environmental Science & Technology, College of Agriculture, Rajendranagar
Soil Quality Kit-Guides for Educators. United States Department of Agriclture Natural resources
conservation service
Soil Taxonomy (2nd edition) Soil Survey Staff. 1999. USDA-NRCS, Washington, DC Agriculture
Handbook 436 Retrieved August 29, 2016 from
http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/nedc/training/soil/?cid=nrcs142p2_0
53577