2. SSooiill iiss ccoommppoosseedd ooff::
 rock particles
 humus
 mineral salts
 water
 air
 organisms

4. RRoocckk ppaarrttiicclleess
vary in size
Gravel Sand Silt Clay

5. TThhrreeee ttyyppeess ooff SSooiill::
Clay Sandy
Loam
BBEESSTT
TTYYPPEE

6. TThhrreeee ttyyppeess ooff ssooiill::--
22 SSaanndd :: 11 CCllaayy

8. CCllaayy SSooiill::
 heavy soil
 difficult to dig as clay sticks

9. CCllaayy SSooiill::
 when dry it forms hard clods
 little air present
Clay Sandy
Loam

10. CCllaayy SSooiill::
retains water
soil becomes waterlogged

11. A waterlogged soil has few air
spaces as these become filled with
water

12. PPaarrttiiccllee ssiizzee aaffffeeccttss tthhee
ffoolllloowwiinngg pprrooppeerrttiieess ooff ssooiill::--
1. amount of air

13. PPaarrttiiccllee ssiizzee aaffffeeccttss tthhee
ffoolllloowwiinngg pprrooppeerrttiieess ooff ssooiill::--
2. the rate and amount of drainage

14. 3. the rise of
water in the
soil
(capillarity)
CCaappiillllaarryy wwaatteerr

15. The smaller the particle size,
the higher water rises.

16. QQuueessttiioonn:: [[AAPPRRIILL,, 22001100]]
PPaappeerr 22BB
List TWO properties of soil that
are affected by soil texture. (4)
 The distance between soil particles
 The amount of air between soil
crumbs/drainage
 The rise of water in the soil
(capillarity)
Any TWO

17. CCllaayy SSooiill iiss mmaaddee lliigghhtteerr bbyy
aaddddiinngg::--
i) humus
How do these work?
ii) lime

18. AAddddiinngg
lliimmee

19. CClluummppiinngg ooff ssooiill ppaarrttiicclleess
iinnttrroodduucceess aaiirr iinn ssooiill
A clay soil
before
treatment.
lime
humus
A clay soil after
treatment.

20. GGoooodd ccrruummbb ssttrruuccttuurree
[[tteexxttuurree]] ooff ssooiill

21. WWhhaatt iiss ‘‘hhuummuuss’’??
black or dark brown material that
remains after decomposition

22. DDaarrkk ssooiill:: rriicchh iinn hhuummuuss

23. 0-45cm
45-90cm
Bedrock
Upper topsoil layer is
dark. Why?
Lower soil layer is rich
Lower soil layer is rich
in salts. Why?
in salts. Why?

24. QQuueessttiioonn:: [[AAPPRRIILL,, 22001100]] PPaappeerr 22BB
Explain how humus:
i) Increases the soil’s water
content. (2)
Absorbing large amounts of water
or reducing evaporation from the
soil.

25. QQuueessttiioonn:: [[AAPPRRIILL,, 22001100]] PPaappeerr 22BB
b. Explain how humus:
ii) Improves the texture of a clay
soil. (2)
Humus helps soil particles
stick together into larger crumbs.

27. SSaannddyy SSooiill::
 light soil
 water drains quickly
As water drains
quickly TWO
disadvantages
result:

28. 11.. SSooiill ddrriieess uupp qquuiicckkllyy
Why is this a disadvantage for the
farmer?
Water is expensive!!

29. 22.. SSaallttss aarree lleeaacchheedd eeaassiillyy
LLeeaacchhiinngg::
ssaallttss ddiissssoollvvee &&
aarree lloosstt

30. SSaannddyy SSooiill iiss iimmpprroovveedd bbyy::
adding humus as this:-
1.holds more water
2.provides salts

31. SSooiill iiss ccoommppoosseedd ooff::
 rock particles
 humus
 mineral salts
 water
 air
 organisms

32. HHuummuuss
a jam-like substance made up of
decayed plants and animals
is found in the topsoil
– blackish in colour

33. HHuummuuss
if there is not enough oxygen,
materials accumulate to form
half decayed materials called
peat
peat decays into humus if placed
in well aerated soil

34. HHuummuuss
helps to clump soil particles into
crumbs

35. HHuummuuss iimmpprroovveess ssooiill bbyy::--
providing mineral salts from
decay by bacteria and fungi
providing air spaces
retaining water
improves crumb structure
(prevents soil from being blown
away)

37. LLooaamm SSooiill
ccoonnttaaiinnss ttwwiiccee aass mmuucchh ssaanndd aass
ccllaayy
Clay [1 part]
Sand [2 parts]
silt

38. HHooww ccaann yyoouu
sseeppaarraattee tthhee ssooiill
ppaarrttiicclleess aass sshhoowwnn
iinn tthhee cchhaarrtt??
 add water
 mix
 leave to
settle

39. EExxppeerriimmeenntt
To find the components of
soil.

41. EExxppeerriimmeenntt
To find the organic content of
soil.

42. percentage of organic matter =
loss in weight ´
weight of original dry sample
100
Original weight: 105 g
Final weight: 100 g
Loss in weight: 5 g
5 ´100 = 4.8%
105

43. SSOOIILL
 rock particles
 humus
 mineral salts
 water
 air
 organisms

44. WWaatteerr
is found as thin films around soil
particles
water moves
upwards towards
the surface by
capillarity

45. EExxppeerriimmeenntt
To find the water content of
soil.

48. PPrreeccaauuttiioonn wwhheenn hheeaattiinngg ssooiill::
Temperature must NOT be more
than 100°C.
WHY?

49. PPeerrcceennttaaggee ooff wwaatteerr iinn ssooiill::
loss in weight ´
original wet sample
100
Original wet weight: 200 g
Final weight: 185 g
Loss in weight: 15 g
15 ´100 = 7.5%
200

50. SSOOIILL
 rock particles
 humus
 mineral salts
 water
 air
 organisms

51. TTWWOO ssoouurrcceess ooff ssaallttss iinn ssooiill::
1. rock erosion
2. decay of dead organisms

52. SSaalliinniissaattiioonn iiss aa SSooiill PPrroobblleemm
 gradual accumulation of salt in the soil, usually due to
improper irrigation techniques
 often in arid and semi-arid
areas (natural mineral salt
conc. high)
– The little precipitation that
falls is quickly evaporated
– Leaves behind salts
 salt concentrations get to
levels toxic to plants

53. MMaannyy oorrggaanniissmmss bbrriinngg aabboouutt
ddeeccaayy::

54. EExxppeerriimmeenntt
To compare the drainage of two
soil samples.

55. SSOOIILL
 rock particles
 humus
 mineral salts
 water
 air
 organisms

56. AAiirr iiss uusseedd bbyy::
1. roots for
respiration
2. decomposers to
decay material into
humus

57. A good ssooiill hhaass aa lloott ooff aaiirr
ssppaacceess bbeettwweeeenn tthhee ccrruummbbss
How can a
farmer
introduce
air into
the soil?

58. By ploughing

59. EExxppeerriimmeenntt
To estimate the volume of air in a
soil.

60. EExxppeerriimmeenntt
percentage of air = volume of air in soil
volume of soil sample
´ 100
Conclusion:
 Air is important in soil for roots to respire
and for decomposers to remain alive.

61.  rock particles
 humus
 mineral salts
 water
 air
 organisms
SSOOIILL

63. BBaacctteerriiaa && FFuunnggii
make salts
available to
plants

64. EEaarrtthhwwoorrmmss iimmpprroovvee ssooiill bbyy::
1. their burrows they mix and loosen the soil
and so help to drain and aerate it
2. providing salts due to their wastes and by
pulling leaves into the soil

65. EEaarrtthhwwoorrmmss iimmpprroovvee ssooiill bbyy::
3. making the soil alkaline as it passes
through their intestine – bacterial growth is
favoured by this pH

66. EEaarrtthhwwoorrmmss iimmpprroovvee ssooiill bbyy::
4. binding soil particles together by the
secretions from the intestines
5. making the soil finer – young roots can
emerge easier

67. HHaarrmmffuull OOrrggaanniissmmss
Nematodes can be harmful by:-
1.feeding on bacteria
2.being ectoparasites and pierce
root
3.being endoparasites and damage
roots and crops

68. HHaarrmmffuull OOrrggaanniissmmss
various insect larvae eat the
roots of plants e.g. wireworms
(beetle larvae)

69. SSooiill ffeerrttiilliittyy ccaann bbee iinnccrreeaasseedd
bbyy::
1. Adding fertilisers
2. Crop rotation
3. Ploughing
4. Keeping a neutral pH

70. TTwwoo ttyyppeess ooff SSooiill FFeerrttiilliisseerr
1. Natural fertilisers
2. Artificial /
Chemical fertilisers

71. NNaattuurraall FFeerrttiilliisseerrss
Animal manure
Compost

73. WWhhyy iiss tthhee tteemmppeerraattuurree aatt tthhee
cceennttrree ooff tthhee ccoommppoosstt ppiillee
hhiigghheerr tthhaann aammbbiieenntt
tteemmppeerraattuurree??

74. Heat released by microbes is
difficult to be lost to the
surroundings – far from surface.
Cool
air in
Cool
air in
Warm air out

75. AAddvvaannttaaggeess ooff NNaattuurraall
FFeerrttiilliisseerrss
provide a wide variety of salts
maintain the crumb structure
long-lasting

76. DDiissaaddvvaannttaaggeess ooff NNaattuurraall
FFeerrttiilliisseerrss
Salts are released slowly – decay is
slow
Bad smell
Pests can grow in it

77. AArrttiiffiicciiaall FFeerrttiilliisseerrss
Manufactured from chemical
compounds

78. AAddvvaannttaaggeess ooff AArrttiiffiicciiaall
FFeerrttiilliisseerrss
Salts are very soluble and are quickly
available to the plant
No pests in it
No unpleasant smell

79. DDiissaaddvvaannttaaggeess ooff AArrttiiffiicciiaall
FFeerrttiilliisseerrss
salts are leached quickly
destroy the crumb structure (soil
becomes a powder)

80. DDiissaaddvvaannttaaggeess ooff AArrttiiffiicciiaall
FFeerrttiilliisseerrss
have less types of salts than manure
no water-holding capacity

81. DDeessccrriibbee wwhhaatt mmaayy hhaappppeenn ttoo aa ssooiill wwhheenn
oonnllyy cchheemmiiccaall
ffeerrttiilliizzeerrss aarree uusseedd oovveerr aa lloonngg ttiimmee ppeerriioodd..
loss of soil humus/organic matter content;
loss of soil texture/crumb structure;
impaired soil drainage/waterlogging;
loss of aeration;
Good
crumb
structure
Bad
crumb
structure

82. QQuueessttiioonn:: [[SSEEPP,, 22001111]] PPaappeerr 22
List TWO types of natural fertiliser.
(2)
1. Compost / peat
2. Animal manure

83. QQuueessttiioonn:: [[MMAAYY,, 22001111]] PPaappeerr 11
Give the biological explanation of the
message in the following poster. (3)
Decomposers, consisting of
bacteria and fungi, bring
about the decay of the dead
plant material. The decaying
material is called compost
and is vital for the growth of
plants as mineral ions are
released into the soil. Plants
use nitrates, phosphates and
other mineral salts to keep
healthy.

84. SSooiill ffeerrttiilliittyy ccaann bbee iinnccrreeaasseedd
bbyy::
1. Adding fertilisers
2. Crop rotation
3. Ploughing
4. Keeping a neutral pH

85. CCrroopp rroottaattiioonn
means the planned order of specific
crops planted on the same field
 rotation may vary from 2 or 3 year or
longer period
 e.g.
- wheat in autumn
- root crop in summer
- barley or oats in spring
- leguminous plants (clover, peas)

86. if the same crop is planted:
certain salts are depleted

87. BBeenneeffiittss ooff CCrroopp
rroottaattiioonn
1. maintains crumb structure
2. supplies nitrates
3. reduces infection to plants as a
pest cannot continue its life cycle if
a different crop is planted

88. SSooiill ffeerrttiilliittyy ccaann bbee iinnccrreeaasseedd
bbyy::
1. Adding fertilisers
2. Crop rotation
3. Ploughing
4. Keeping a neutral pH

89. Beneficial effects of ploughing:
makes soil porous so water drains
better
 introduces air into the soil

90. Beneficial effects of ploughing:
 incorporates the residue from the
previous crop into the soil
 reduces the prevalence of weeds in
the fields

91. TTHHEE EENNDD