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Lecture

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Soils and soil forming factors. The rhizosphere. Some alternate methods ... The USFS Calhoun Experimental Forest in the 1950's. Union County, South Carolina. 55 ... – PowerPoint PPT presentation

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Title: Lecture


1
Lecture 6 Plant Nutrition and Soils
Image a soil profile
2
Key Concepts
  • Resources
  • Which are required
  • How they are used
  • Essential elements
  • What they are
  • What they do
  • Soils and soil forming factors
  • The rhizosphere
  • Some alternate methods to acquire nutrients

3
Resource requirements for plant growth???
?
4
Where do plants get these resources???
?
5
Where do plants get these resources???
6
Image root system of a grass
Diagram plant resource requirements and sources
7
Plant tissue composition by weight
  • Fresh herbaceous tissue is 80-85 water
  • Little water is incorporated into plant tissue
  • What does water contribute to tissue???
  • Most water is in the cell solution, in the
    vacuoles, or passing through in the transpiration
    stream

8
Critical Thinking
  • Does wood have such a high percentage of water???

9
Critical Thinking
  • Does wood have such a high percentage of water???

10
Plant tissue composition by weight
  • Fresh herbaceous tissue is 80-85 water
  • Little water is incorporated into plant tissue
  • What does water contribute to tissue???
  • Most water is in the cell solution, in the
    vacuoles, or passing through in the transpiration
    stream

11
Plant tissue composition by weight
  • Fresh herbaceous tissue is 80-85 water
  • Little water is incorporated into plant tissue
  • Water supplies all the H to carbohydrates
    electrons and protons for photosynthesis
  • Most water is in the cell solution, in the
    vacuoles, or passing through in the transpiration
    stream

12
Plant tissue composition by weight
  • Fresh herbaceous tissue is 80-85 water
  • Little water is incorporated into plant tissue
  • Water contributes H to carbohydrates electrons
    and protons for photosynthesis
  • Most water is in the cell solution, in the
    vacuoles, or passing through in the transpiration
    stream

13
DRY plant tissue composition by weight
  • 45 carbon
  • 45 oxygen
  • 6 hydrogen
  • 5 inorganic mineral nutrients

14
DRY plant tissue composition by weight
  • 45 carbon from ?? CO2
  • 45 oxygen from ?? CO2
  • 6 hydrogen from ?? water
  • 5 inorganic mineral nutrients from ?? soil

15
DRY plant tissue composition by weight
  • 45 carbon from
  • 45 oxygen from
  • 6 hydrogen from
  • 5 inorganic mineral nutrients from

16
DRY plant tissue composition by weight
  • 45 carbon from
  • 45 oxygen from
  • 6 hydrogen from
  • 5 inorganic mineral nutrients from

17
C, H, O source and fate in photosynthesis
Diagram what goes into photosynthesis and what
comes out
18
DRY plant tissue composition by weight
  • 45 carbon from CO2
  • 45 oxygen from CO2
  • 6 hydrogen from water
  • 5 inorganic mineral nutrients from
  • 0.75-1 of wet weight, but many are essential to
    plant growth and function

19
Critical Thinking
  • What is the difference between a chemical
    element, a molecule and a macromolecule???

20
Critical Thinking
  • What is the difference between a chemical
    element, a molecule and a macromolecule???

Diagram structure of chlorophyll molecule
21
Essential Elements
  • Chemical elements
  • Not molecules, though some are delivered in that
    form N vs. NO3-
  • Required for growth and function of the plant
  • Cant be replaced by some other element
  • Some contribute to structural components
  • Some contribute to metabolic processes or the
    maintenance of homeostasis

22
Essential elements in structural plant components
  • What are some essential structural components???

?
23
Essential elements in structural plant components
24
Essential elements in structural plant components
25
Essential elements for metabolic processes
  • What are some essential molecules used in
    metabolic processes???

?
26
Essential elements for metabolic processes
27
Essential elements for metabolic processes
28
Macro Nutrients vs. Micro Nutrients
mass
  • Nitrogen
  • Potassium
  • Calcium
  • Magnesium
  • Phosphorous
  • Sulfur
  • Chlorine, Iron, Boron, Manganese, Zinc, Copper
    and Molybdenum
  • Some plants also require Nickel, Sodium, Silicon,
    Selenium or others

All used in large quantities to support the
structures and processes listed before
Mostly used in enzymes, as enzyme cofactors or in
electron transfers often reused, less required
29
Study table in book!
Table essential nutrients, both macro and micro
30
Memory device in honor of my friend and mentor,
Dr. Chuck Davey celebrated in 2006 for 50 years
of service to soil science!!!
  • C HOPKNS CaFe, Mg, Mn B CuZn Mo, Cl
  • C. Hopkin's cafe, mighty good, managed by cousin
    Mo, waitress Clara
  • Nickel may also be essential

31
Some minerals required, some by chance
Images various plants that use additional
elements
Sulfur in mustards
Silicon in horsetails
Uranium in macadamia nuts
32
Critical Thinking
  • How do you tell which are required???

33
Critical Thinking
  • How do you tell which are required???

34
Critical Thinking
  • How do you tell which are required???
  • How would elements NOT required enter the plant
    tissue???

35
Critical Thinking
  • How do you tell which are required???
  • How would elements NOT required enter the plant
    tissue???

36
All plants will exhibit signs of deficiencies..
Images signs of deficiency
37
Critical Thinking
  • If the deficiency appears first in the older
    leaves, is that nutrient mobile or immobile???

38
Critical Thinking
  • If the deficiency appears first in the older
    leaves, is that nutrient mobile or immobile???
  • How???

39
Critical Thinking
  • If the deficiency appears first in the older
    leaves, is that nutrient mobile or immobile???
  • How???

40
Fe deficiency in younger leaves ()
Mg deficiency in older leaves ()
41
Critical Thinking
  • Why would some elements be mobile, and others
    not???

42
Critical Thinking
  • Why would some elements be mobile, and others
    not???

43
Most plants get most of their nutrients from the
soil absorbed through the roots
Image roots
44
Soil is not just Dirt!
  • Soil is the skin of the earth
  • Soil provides for virtually all our food
  • Soil supports the forests that maintain the
    hydrological cycle
  • Soil supports virtually all terrestrial
    ecosystems from micro-organisms to charismatic
    macro-fauna

45
The results of deforestation are ecological,
economic and social disaster ( )
Image erosion after tropical deforestation
46
Removing the plants removes the soils protective
blanket and erosion is almost inevitable
47
Erosion from deforestation in Madagascar
More images erosion
48
Sedimentation from erosion this represents a
huge loss of soil capital
Image sediments from eroded land flooding out
to sea
49
Sediments eroding off Haiti
Image sediments eroding off Haiti into the sea
50
Dominican Republic
Image the political boundary is clear from the
deforestation
Haiti
51
Haitis drought is caused largely by
deforestation the hydrological cycle has been
snapped
Image the drought in Haiti, where residents eat
mud to survive
52
Deforestation in Warwickshire, England
Maps deforestation in England and in the US
Deforestation in the US
53
Map soil loss in the Southern Piedmont of the
US due to deforestation and abusive agricultural
practices
Piedmont soil erosion in the southeastern US
54
Image eroded land in the Southern Piedmont
The USFS Calhoun Experimental Forest in the
1950s Union County, South Carolina
55
Loss of soil (along with the boll weevil) nearly
eliminated productive agriculture in the Southern
Piedmont after the 1920s now most of the
Piedmont is in industrial pine plantations
because it can no longer support productive
agriculture
Maps loss of farms, rise of industrial
forestry, creating the biological deserts of pine
plantations
56
Social Justice You can help!!!
57
Compassionate Thinking
  • What can you do to help???

58
Compassionate Thinking
  • What can you do to help???

59
SoilA dynamic natural body in which plants
grow, composed of mineral and organic materials,
air, water, and living organisms
60
SoilA dynamic natural body in which plants
grow, composed of mineral and organic materials,
air, water, and living organisms
61
SoilA dynamic natural body in which plants
grow, composed of mineral and organic materials,
air, water, and living organisms
62
SoilA dynamic natural body in which plants
grow, composed of mineral and organic materials,
air, water, and living organisms
63
SoilA dynamic natural body in which plants
grow, composed of mineral and organic materials,
air, water, and living organisms
64
SoilA dynamic natural body in which plants
grow, composed of mineral and organic materials,
air, water, and living organisms
65
SoilA dynamic natural body in which plants
grow, composed of mineral and organic materials,
air, water, and living organisms
66
SoilA dynamic natural body in which plants
grow, composed of mineral and organic materials,
air, water, and living organisms
67
SoilA dynamic natural body in which plants
grow, composed of mineral and organic materials,
air, water, and living organisms
68
SoilA dynamic natural body in which plants
grow, composed of mineral and organic materials,
air, water, and living organisms
69
Soil Forming FactorsParent MaterialClimateLiv
ing OrganismsTopographyTime
All soil forming factors interact!!!
70
Parent Material
  • The substrate from which soil forms
  • May be bedrock or some deposited material
    (sediments, organic material)
  • Determines soil texture, mineral content
  • Influences soil structure and pH

71
Igneous rocks form from molten rock
72
Pegmatite granite with large-grained feldspar
(slow cooling)
73
Sedimentary rocks form from deposited materials
74
Flat sedimentary rocks
Sedimentary rocks after tectonic thrusting and
folding
75
Metamorphic rocks form from igneous or
sedimentary rocks that have been altered by heat
and pressure
76
gneiss
77
In the Charleston area, our soils form from
unconsolidated Coastal Plain sediments
78
Critical Thinking
  • Why???

79
Critical Thinking
  • Why???

80
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81
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82
PM determines soil texture percentage of sand,
silt and clay Loam soils have equal
percentage of each texture class
83
CLAY
84
Clays are especially important
  • Tiny (lt2um)
  • Huge surface area per unit mass (1000X more than
    same volume of sand)
  • Typically platy in structure vast additional
    internal surface area (800 m2/gm)
  • Typically clay minerals carry a negative charge

85
Critical Thinking
  • Why is a huge surface area of negative charge
    important to soil fertility???

86
Critical Thinking
  • Why is a huge surface area of negative charge
    important to soil fertility???

87
Most clays carry negative charge on both external
and internal surfaces
88
Cation Exchange remember the root cap protons
displace cations
89
Texture also influences soil moisture clays
hold onto more water Small pore size and
negative charge Relationship between soil
texture, field capacity and water availability
90
Parent materials are weathered by other soil
forming factors to form soil
91
Soils are typically layered, in horizons, because
of downward movement of water, clays, etc
92
Critical Thinking
  • Which soil horizon has the most biological
    activity???
  • Why???

93
Critical Thinking
  • Which soil horizon has the most biological
    activity???
  • Why???

94
A Horizon The topsoil is the most biologically
active horizon more air, water and organic
materials from the surface
95
Soil Profile a cut that reveals the horizons
96
Climate
  • Primarily temperature and precipitation patterns
  • Temperature controls freeze-thaw cycles that
    contribute to physical weathering
  • Temperature also affects the rate of biochemical
    reactions
  • Temperature also affects the rate of
    decomposition by fungi, bacteria, and other
    living organisms

97
Climate
  • Precipitation contributes to soil moisture, which
    affects plant growth and the activity of
    decomposing organisms
  • Precipitation affects erosion (the physical loss
    of soil particles) and leaching (chemical losses
    from the soil solution as water passes through
    the soil this contributes to profile formation)

98
Major biomes are determined by climate
microclimate is also important in soil development
99
Living Organisms
  • Macro-organisms, including plants and animals
  • Micro-organisms, including bacteria, fungi,
    single-celled protists, and micro-fauna
  • Human activity typically results in abrupt and
    very negative changes to soil

100
Living Organisms Plants
  • Contribute organic material both from above
    (shoots) and below (roots), and both sources
    affect horizonation
  • Help to mix the soil root channels, wind throws
  • Cycle nutrients from soil to plant and back
    (sometimes through animals, always through
    decomposers)
  • Help prevent soil erosion by breaking the force
    of rain, providing a litter layer

101
Same parent material will develop into a
different soil under different plant communities
102
Critical Thinking
  • Why are grassland soils so dark at the surface???

103
Critical Thinking
  • Why are grassland soils so dark at the surface???

104
Living Organisms Animals
  • Help to mix the soil by burrowing, some even
    eat soil (earthworms)
  • Contribute organic material when they die
  • Contribute to nutrient cycling

105
Critical Thinking
  • How do animals contribute to nutrient cycling???

106
Critical Thinking
  • How do animals contribute to nutrient cycling???

107
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108
Living Organisms Micro-orgs
  • Decompose organic material, cycle nutrients, add
    OM
  • Trillions/kg of soil (double handful of soil.)
  • N-fixing bacteria supply virtually all N for
    plant growth, either free living or in nodule
  • the nitrogen paradox.bacteria convert
    atmospheric N to forms suitable for plant uptake
  • Mycorrhizae mutual symbiotic association
    between fungi and roots, present in most plants,
    required by some

109
Small animals, soil dwelling micro-fauna, fungi,
bacteria, and other micro-organisms decompose
dead OM, cycling nutrients back into the soil
110
Living Organisms Micro-orgs
  • Decompose organic material, cycle nutrients, add
    OM
  • Trillions/kg of soil (double handful of soil.)
  • N-fixing bacteria supply virtually all N for
    plant growth, either free living or in nodule
  • The nitrogen paradox.bacteria convert
    atmospheric N to forms suitable for plant uptake
  • Mycorrhizae mutual symbiotic association
    between fungi and roots, present in most plants,
    required by some

111
N-fixing bacteria in symbiotic mutualisms, mostly
with legumes
112
Living Organisms Micro-orgs
  • Decompose organic material, cycle nutrients, add
    OM
  • Trillions/kg of soil (double handful of soil.)
  • N-fixing bacteria supply virtually all N for
    plant growth, either free living or in nodule
  • the nitrogen paradox.bacteria convert
    atmospheric N to forms suitable for plant uptake
  • Mycorrhizae mutual symbiotic association
    between fungi and roots, present in most plants,
    required by some

113
Critical Thinking
  • What do you think mycorrhizae might contribute to
    the symbiosis???

114
Critical Thinking
  • What do you think mycorrhizae might contribute to
    the symbiosis???

115
Mycorrhizae are symbiotic mutualisms between
fungi and plants fungal hyphae vastly increase
surface area for water and nutrient absorption
85 of plants depend on them
116
Living Organisms The human impact
  • Removing vegetation dramatically increases
    erosion, cultivation exacerbates
  • Deforestation can snap hydrological cycles
  • Excessive fertilizer and pesticide use
    contaminates both soil and water
  • Improper irrigation salinates soil
  • Wetland drainage damages wetland soils
  • and on.

117
Topography the shape of the land
  • Determines the movement of water, thus affecting
    erosion and leaching rates
  • Determines where water accumulates, which affects
    soil moisture, which affects organismal activity,
    which affects soils.
  • Aspect affects the amount of solar radiation at
    the surface, and thus soil temperature
  • Large topographic features influence
    precipitation patterns
  • Even micro-topography influences plant
    distribution

118
Topographic Aspect red and blue face S and W
green and yellow face N and E
119
Critical Thinking
  • Why are the north and east slopes of a hill
    cooler???

120
Critical Thinking
  • Why are the north and east slopes of a hill
    cooler???

121
Topography the shape of the land
  • Determines the movement of water, thus affecting
    erosion and leaching rates
  • Determines where water accumulates, which affects
    soil moisture, which affects organismal activity,
    which affects soils.
  • Aspect affects the amount of solar radiation at
    the surface, and thus soil temperature
  • Large topographic features influence
    precipitation patterns
  • Even micro-topography influences plant
    distribution

122
Orographic lifting makes it rain
123
Critical Thinking
  • What the heck is orographic lifting and why does
    it cause rain???

124
Critical Thinking
  • What the heck is orographic lifting and why does
    it cause rain???

125
Critical Thinking
  • What the heck is orographic lifting and why does
    it cause rain???

126
Orographic lifting causes cooling and
precipitation, rain shadow to the leeward
127
Topography the shape of the land
  • Determines the movement of water, thus affecting
    erosion and leaching rates
  • Determines where water accumulates, which affects
    soil moisture, which affects organismal activity,
    which affects soils.
  • Aspect affects the amount of solar radiation at
    the surface, and thus soil temperature
  • Large topographic features influence
    precipitation patterns
  • Even micro-topography influences plant
    distribution

128
Small change in elevation
big change in the plant community!
129
Time.
  • The length of time all these factors have been
    acting determines the characteristics of the soil
  • The same parent material will develop different
    soils as time passes
  • Major component of primary succession

130
Soil development on glacial till
131
Soil Forming FactorsParent MaterialClimateLiv
ing OrganismsTopographyTime
Remember all soil forming factors interact!!!
132
The Rhizosphere
The area of interaction between root and soil. A
huge volume of soil, but a very narrow zone
133
The rhizosphere is the zone of cation exchange,
nutrient and water uptake
134
The Rhizosphere
  • Complex zone with many interacting factors
  • Plant affects soil through compounds secreted by
    the plants roots
  • Relative proportions of nutrients in the soil
    solution can affect uptake of all nutrients
  • Also, different species have different nutrient
    requirements
  • Rhizosphere is the control zone for plant/soil
    interactions

135
Some plants use alternate methods to absorb some
nutrients
  • Parasites, saprophytes, carnivores

136
Key Concepts QUESTIONS???
  • Resources
  • Which are required
  • How they are used
  • Essential elements
  • What they are
  • What they do
  • Soils and soil forming factors
  • The rhizosphere
  • Some alternate methods to acquire nutrients
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