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Soil

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Soil

  1. 1. SSooiill iiss ccoommppoosseedd ooff::  rock particles  humus  mineral salts  water  air  organisms
  2. 2. RRoocckk ppaarrttiicclleess vary in size Gravel Sand Silt Clay
  3. 3. TThhrreeee ttyyppeess ooff SSooiill:: Clay Sandy Loam BBEESSTT TTYYPPEE
  4. 4. TThhrreeee ttyyppeess ooff ssooiill::-- 22 SSaanndd :: 11 CCllaayy
  5. 5. CCllaayy SSooiill::  heavy soil  difficult to dig as clay sticks
  6. 6. CCllaayy SSooiill::  when dry it forms hard clods  little air present Clay Sandy Loam
  7. 7. CCllaayy SSooiill:: retains water soil becomes waterlogged
  8. 8. A waterlogged soil has few air spaces as these become filled with water
  9. 9. PPaarrttiiccllee ssiizzee aaffffeeccttss tthhee ffoolllloowwiinngg pprrooppeerrttiieess ooff ssooiill::-- 1. amount of air
  10. 10. PPaarrttiiccllee ssiizzee aaffffeeccttss tthhee ffoolllloowwiinngg pprrooppeerrttiieess ooff ssooiill::-- 2. the rate and amount of drainage
  11. 11. 3. the rise of water in the soil (capillarity) CCaappiillllaarryy wwaatteerr
  12. 12. The smaller the particle size, the higher water rises.
  13. 13. 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
  14. 14. CCllaayy SSooiill iiss mmaaddee lliigghhtteerr bbyy aaddddiinngg::-- i) humus How do these work? ii) lime
  15. 15. AAddddiinngg lliimmee
  16. 16. CClluummppiinngg ooff ssooiill ppaarrttiicclleess iinnttrroodduucceess aaiirr iinn ssooiill A clay soil before treatment. lime humus A clay soil after treatment.
  17. 17. GGoooodd ccrruummbb ssttrruuccttuurree [[tteexxttuurree]] ooff ssooiill
  18. 18. WWhhaatt iiss ‘‘hhuummuuss’’?? black or dark brown material that remains after decomposition
  19. 19. DDaarrkk ssooiill:: rriicchh iinn hhuummuuss
  20. 20. 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?
  21. 21. 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.
  22. 22. 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.
  23. 23. SSaannddyy SSooiill::  light soil  water drains quickly As water drains quickly TWO disadvantages result:
  24. 24. 11.. SSooiill ddrriieess uupp qquuiicckkllyy Why is this a disadvantage for the farmer? Water is expensive!!
  25. 25. 22.. SSaallttss aarree lleeaacchheedd eeaassiillyy LLeeaacchhiinngg:: ssaallttss ddiissssoollvvee && aarree lloosstt
  26. 26. SSaannddyy SSooiill iiss iimmpprroovveedd bbyy:: adding humus as this:- 1.holds more water 2.provides salts
  27. 27. SSooiill iiss ccoommppoosseedd ooff::  rock particles  humus  mineral salts  water  air  organisms
  28. 28. HHuummuuss a jam-like substance made up of decayed plants and animals is found in the topsoil – blackish in colour
  29. 29. 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
  30. 30. HHuummuuss helps to clump soil particles into crumbs
  31. 31. 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)
  32. 32. LLooaamm SSooiill ccoonnttaaiinnss ttwwiiccee aass mmuucchh ssaanndd aass ccllaayy Clay [1 part] Sand [2 parts] silt
  33. 33. HHooww ccaann yyoouu sseeppaarraattee tthhee ssooiill ppaarrttiicclleess aass sshhoowwnn iinn tthhee cchhaarrtt??  add water  mix  leave to settle
  34. 34. EExxppeerriimmeenntt To find the components of soil.
  35. 35. EExxppeerriimmeenntt To find the organic content of soil.
  36. 36. 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
  37. 37. SSOOIILL  rock particles  humus  mineral salts  water  air  organisms
  38. 38. WWaatteerr is found as thin films around soil particles water moves upwards towards the surface by capillarity
  39. 39. EExxppeerriimmeenntt To find the water content of soil.
  40. 40. PPrreeccaauuttiioonn wwhheenn hheeaattiinngg ssooiill:: Temperature must NOT be more than 100°C. WHY?
  41. 41. 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
  42. 42. SSOOIILL  rock particles  humus  mineral salts  water  air  organisms
  43. 43. TTWWOO ssoouurrcceess ooff ssaallttss iinn ssooiill:: 1. rock erosion 2. decay of dead organisms
  44. 44. 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
  45. 45. MMaannyy oorrggaanniissmmss bbrriinngg aabboouutt ddeeccaayy::
  46. 46. EExxppeerriimmeenntt To compare the drainage of two soil samples.
  47. 47. SSOOIILL  rock particles  humus  mineral salts  water  air  organisms
  48. 48. AAiirr iiss uusseedd bbyy:: 1. roots for respiration 2. decomposers to decay material into humus
  49. 49. A good ssooiill hhaass aa lloott ooff aaiirr ssppaacceess bbeettwweeeenn tthhee ccrruummbbss How can a farmer introduce air into the soil?
  50. 50. By ploughing
  51. 51. EExxppeerriimmeenntt To estimate the volume of air in a soil.
  52. 52. 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.
  53. 53.  rock particles  humus  mineral salts  water  air  organisms SSOOIILL
  54. 54. BBaacctteerriiaa && FFuunnggii make salts available to plants
  55. 55. 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
  56. 56. EEaarrtthhwwoorrmmss iimmpprroovvee ssooiill bbyy:: 3. making the soil alkaline as it passes through their intestine – bacterial growth is favoured by this pH
  57. 57. 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
  58. 58. 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
  59. 59. HHaarrmmffuull OOrrggaanniissmmss various insect larvae eat the roots of plants e.g. wireworms (beetle larvae)
  60. 60. SSooiill ffeerrttiilliittyy ccaann bbee iinnccrreeaasseedd bbyy:: 1. Adding fertilisers 2. Crop rotation 3. Ploughing 4. Keeping a neutral pH
  61. 61. TTwwoo ttyyppeess ooff SSooiill FFeerrttiilliisseerr 1. Natural fertilisers 2. Artificial / Chemical fertilisers
  62. 62. NNaattuurraall FFeerrttiilliisseerrss Animal manure Compost
  63. 63. WWhhyy iiss tthhee tteemmppeerraattuurree aatt tthhee cceennttrree ooff tthhee ccoommppoosstt ppiillee hhiigghheerr tthhaann aammbbiieenntt tteemmppeerraattuurree??
  64. 64. Heat released by microbes is difficult to be lost to the surroundings – far from surface. Cool air in Cool air in Warm air out
  65. 65. AAddvvaannttaaggeess ooff NNaattuurraall FFeerrttiilliisseerrss provide a wide variety of salts maintain the crumb structure long-lasting
  66. 66. DDiissaaddvvaannttaaggeess ooff NNaattuurraall FFeerrttiilliisseerrss Salts are released slowly – decay is slow Bad smell Pests can grow in it
  67. 67. AArrttiiffiicciiaall FFeerrttiilliisseerrss Manufactured from chemical compounds
  68. 68. AAddvvaannttaaggeess ooff AArrttiiffiicciiaall FFeerrttiilliisseerrss Salts are very soluble and are quickly available to the plant No pests in it No unpleasant smell
  69. 69. DDiissaaddvvaannttaaggeess ooff AArrttiiffiicciiaall FFeerrttiilliisseerrss salts are leached quickly destroy the crumb structure (soil becomes a powder)
  70. 70. DDiissaaddvvaannttaaggeess ooff AArrttiiffiicciiaall FFeerrttiilliisseerrss have less types of salts than manure no water-holding capacity
  71. 71. 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
  72. 72. QQuueessttiioonn:: [[SSEEPP,, 22001111]] PPaappeerr 22 List TWO types of natural fertiliser. (2) 1. Compost / peat 2. Animal manure
  73. 73. 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.
  74. 74. SSooiill ffeerrttiilliittyy ccaann bbee iinnccrreeaasseedd bbyy:: 1. Adding fertilisers 2. Crop rotation 3. Ploughing 4. Keeping a neutral pH
  75. 75. 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)
  76. 76. if the same crop is planted: certain salts are depleted
  77. 77. 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
  78. 78. SSooiill ffeerrttiilliittyy ccaann bbee iinnccrreeaasseedd bbyy:: 1. Adding fertilisers 2. Crop rotation 3. Ploughing 4. Keeping a neutral pH
  79. 79. Beneficial effects of ploughing: makes soil porous so water drains better  introduces air into the soil
  80. 80. Beneficial effects of ploughing:  incorporates the residue from the previous crop into the soil  reduces the prevalence of weeds in the fields
  81. 81. TTHHEE EENNDD

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