Transcript Soils for Plant Growth - Master Gardener Volunteer Program

Soils for Plant Growth
A Unit of the
Michigan State University Extension
Master Gardener Curriculum
Soils for Plant Growth
Objectives
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Define soil
Understand its composition
Understand its physical properties
Understand its chemical properties
Identify essential plant nutrients and their
management
Soils for Plant Growth
Objectives
• Understand management practices related to
changing soil properties
• Understand environmental implications of
soil management practices
• Use knowledge gained to analyze and
assess concerns related to soil properties
Soils for Plant Growth
What Is Soil?
Soils for Plant Growth
What Is Soil?
Soils for Plant Growth
What Is Soil?
Soils for Plant Growth
What Is Soil?
Soils for Plant Growth
What Is Soil?
• Not DIRT!!!
• Precious resource
• Loose, unconsolidated material on the
earth’s surface
• Soil scientist’s definition
Soils for Plant Growth
What Is Soil?
“A natural body of the earth’s surface
having characteristics resulting
from climate and living organisms
acting upon parent material
as conditioned by slope
over periods of time”
Soils for Plant Growth
What Is Soil?
• Parent material
• Organisms
Soils for Plant Growth
What Is Soil?
• Parent material
• Organisms
• Climate
• Topography
• Time
Soils for Plant Growth
Soil Provides
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Anchorage
Water
Air
Nutrients
Growth-producing chemical environment
Soils for Plant Growth
Soil Is Composed of
• Mineral solids
• Organic solids
• Pore spaces
Soils for Plant Growth
Ideal Soil Composition
5%
Water
25%
45%
Air
Mineral
25%
Organic
Soils for Plant Growth
Physical Properties of Soil
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Texture
Structure
Pore space
Density
Temperature
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Color
Soil organisms
Organic matter
Groundwater
Soils for Plant Growth
Soil Texture
• Sand
• Silt
• Clay
Soils for Plant Growth
Coarser
Loamy
Sand Sand
Sandy
Loam
Finer
Loam
Silt
Loam
Clay
Loam
Clay
Soils for Plant Growth
100
90
10
20
80
30
70
clay
60
40
silty
clay
50
40
30
20
sandy
clay
clay loam
sandy clay
loam
10
60
silty clay
loam
silt loam
loamy
sand
sand
100
90
80
70
80
loam
sandy loam
50
90
silt
70
60
50
40
30
Percent Sand
20
10
100
Soils for Plant Growth
Soil Structure
Loose
Aggregated
Soils for Plant Growth
Influence of Soil Structure
Dominant texture
Characteristics with
little structure
Characteristics with
greater structure
Clay
Wet,
poorly aerated,
slow permeability
Better aeration,
internal drainage and
permeability
Sand
Droughty
Improved water holding
capacity
Soils for Plant Growth
Texture Vs Structure
• Texture is unchangeable
• Structure can be improved or destroyed
Soils for Plant Growth
Compaction
Good Structure
Compressed Structure
Soils for Plant Growth
Excessive Tillage
Too Much Tillage
Soils for Plant Growth
Porosity
Porosity
Porosity
Porosity
Porosity
Water holding capacity
Drainage
Aeration
Density
Soils for Plant Growth
Macro- and Micropores
Water-filled
microprore
Air-filled
macropore
Soils for Plant Growth
Water Movement
Sand
Loam
Clay
Soils for Plant Growth
Soil Density
Clay
Sand
Soils for Plant Growth
Soil Temperature
Soils for Plant Growth
Soil Color
• Affects soil temperature
• Indicates how much organic matter is
present
• Predicts natural drainage conditions
Soils for Plant Growth
Topsoil Color
Dark
• High organic matter
• Formed under cool,
wet conditions
Light
• Low organic matter
• Formed under warmer,
drier conditions
Soils for Plant Growth
Soil Organisms
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Bacteria
Fungi
Mycorrhizae
Lichens
Protozoa
Invertebrates
Vertebrates
Soils for Plant Growth
Organic Matter Vs Humus
Organic matter
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decomposes to form humus
Leaves
Manure
Grass clippings
Decomposes rapidly
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Highly decomposed
Stable
Rich in nitrogen
Slowly degradable
Soils for Plant Growth
Groundwater
• Stored in aquifers, water-saturated zones
beneath the earth’s surface
• Part of the soil environment if close to the
surface - high water table
• Easily contaminated
Soils for Plant Growth
Points to Remember
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Know the physical characteristics of your soil
Adding organic matter is usually beneficial
Don’t over till
Don’t compact
Maintain groundcover on slopes
Avoid bringing in soil of drastically different
texture
Soils for Plant Growth
Chemical Properties of Soil
CEC
Capacity - Cation Exchange Capacity
pH
Availability
EC
Intensity - Electroconductivity
Ca:Mg
Balance - Nutrient ratios
Soils for Plant Growth
Chemistry 101
Atom
• The smallest unit of a substance that has all
the properties of that substance
• No net electrical charge
• Model behaves a bit like our solar system
Electron (-)
Proton (+)
Neutron
-
+
Soils for Plant Growth
Chemistry 101
Molecule
• A group of atoms connected by chemical
bonds
• No net electrical charge
• Example: H2O - water
H
O
H
Soils for Plant Growth
Chemistry 101
Ion - An atom or molecule that has an
electrical charge due to the loss or gain of
electrons
H2O
+
H +
OH
Soils for Plant Growth
Chemistry 101
Ion
• Cation - an ion with a positive charge
Ca++ Mg++ H+ K+ NH4+
• Anion - an ion with a negative charge
OH- NO3- SO4-- Cl-
Soils for Plant Growth
Chemistry 101
• Unlike charges attract
+
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• Like charges repel
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+
Soils for Plant Growth
Chemical Properties of Soil
CEC
Capacity - Cation Exchange Capacity
– ++Ca
Soil
particle – +K
– ++Mg
Soils for Plant Growth
Cation Exchange Capacity
+H
+K
NH4+
+H +K +NH4
++Ca
Mg++
++Mg
NH4+
++Ca
Humus
Clay
Soils for Plant Growth
Cation Exchange Capacity
CEC
1-5
6 - 10
• Very low with not much clay or humus
• Intermediate loamy texture or sandy with
more humus
10+
• Progressively more clay and/or humus
20+
• Probably an organic soil
Soils for Plant Growth
Chemical Properties of Soil
CEC
pH
Availability
Soils for Plant Growth
What Is pH and Why Is It
Important?
H2O
H+ + OH-
Remember: Everything is dissolved in water
Soils for Plant Growth
Neutral
Acid
Alkaline
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Battery Vinegar
acid
Orange
juice
Pure
water
Baking
soda
Ammonia
Bleach Lye
Soils for Plant Growth
Neutral
Acid
Alkaline
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Blueberries
Alfalfa
Most
plants
Soils for Plant Growth
Factors Influencing Soil pH
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Components of the soil
Lime
Water quality
Type of nitrogen applied
Amount of fertilizer
Crop species
Soils for Plant Growth
What Does This Plant Tell You
about the pH of the Soil?
Soils for Plant Growth
What Does This Plant Tell You
about the pH of the Soil?
Soils for Plant Growth
Chemical Properties of Soil
K+ NO 3
Ca++ ClEC
Intensity - Electroconductivity
Soils for Plant Growth
Chemical Properties of Soil
EC
CEC
Ca:Mg
Fe:Mn
K:Ca:Mg
N:K
pH
Ca:Mg
Balance - Nutrient ratios
Soils for Plant Growth
Essential Elements
HOPKNS Ca Fe
C B Mg
Cl Mn Mo
Cu Zn!
Soils for Plant Growth
Essential Elements
HOPKNS Ca Fe
C B Mg
Cl Mn Mo
Cu Zn!
Soils for Plant Growth
Essential Elements
HOPKNS Ca Fe
C B Mg
Cl Mn Mo
Cu Zn!
Soils for Plant Growth
Macronutrients
• Nitrogen (N as NO3 and NH4)
Soils for Plant Growth
Macronutrients
• Nitrogen (N as NO3 and NH4)
• Phosphorous (P)
– Associated with root growth and flower
development
– Potential pollutant
– Deficiency results in purpling of leaves
Soils for Plant Growth
Macronutrients
• Nitrogen (N as NO3 and NH4)
• Phosphorous (P)
• Potassium (K)
– Reduced growth / vigor
– Marginal necrosis on older leaves
– Wilt
Soils for Plant Growth
Macronutrients
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Nitrogen (N as NO3 and NH4)
Phosphorous (P)
Potassium (K)
Magnesium (Mg)
Calcium (Ca)
Sulfur (S)
Soils for Plant Growth
Essential Elements
HOPKNS Ca Fe
C B Mg
Cl Mn Mo
Cu Zn!
Soils for Plant Growth
Changing Soil Properties
• Changing physical properties
– Bringing in sand / clay / topsoil
– Adding compost
• Changing chemical properties
– Fertilizing
– Adjusting the pH
Soils for Plant Growth
Changing Physical Properties
• Changing soil texture
– Bringing in sand / clay / topsoil
• Changing soil structure
– Adding compost
Soils for Plant Growth
What about Gypsum?
Gypsu
m
Is it a quick fix for clay soils?
Soils for Plant Growth
Fertilizer Composition
120
100
80
60
N
P
K
N
P
46-0-0
2
0-46-0
3
K
40
20
0
12-12-12
1
Inert Material
Urea
0-0-60
4
Tri-Superphosphate Muriate of Potash
Soils for Plant Growth
Pounds of Actual Nitrogen
• 1 pound of actual nitrogen per 1,000 square
feet of lawn
• 3 pounds of actual nitrogen per 1,000
square feet for trees or shrubs
• 2 pounds of actual nitrogen prior to planting
vegetables then side dress with 1 pound of
actual nitrogen
Soils for Plant Growth
How Much Fertilizer?
20-10-5
100 divided by 20 = 5
Soils for Plant Growth
How Much Fertilizer?
46-0-0
? divided by ? = ?
Soils for Plant Growth
Raising Soil pH
• Lime
– Dolomitic lime (calcium and magnesium)
– Calcitic lime (calcium only)
– Hydrated lime (calcium only with faster reaction)
• Wood ashes
Soils for Plant Growth
Lowering Soil pH
• Ammonical nitrogen (ammonium sulfate)
• Iron sulfate
• Acids
• Elemental sulfur
Soils for Plant Growth
Why Test Soil?
• Basis for using lime and fertilizer
• Diagnosing problems
• Evaluating nutrient balances
• Protecting the environment
Soils for Plant Growth
Taking a Soil Sample
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When
Where
How
Amount
Preparing and packaging
Fill out the form completely
Soils for Plant Growth
Interpreting Soil Test Results
• Lawns
Soils for Plant Growth
Interpreting Soil Test Results
• Gardens
Soils for Plant Growth
What Is Soil?
“A natural body of the earth’s surface
having characteristics resulting
from climate and living organisms
acting upon parent material
as conditioned by slope
over periods of time”
Soils for Plant Growth
Horizons
• “A” horizon - topsoil
• “E” horizon - transition
• “B” horizon - subsoil
• “C” horizon - parent material
• “R” horizon - bedrock
Soils for Plant Growth
What’s the Soil Like Where
You Live?
Soils for Plant Growth
What Would You Do?
• New home on
farmland
• Soil compacted
during construction
• Owner wants to
establish a lawn
Soils for Plant Growth
What Would You Do?
• Vegetable garden in full
sun
• Sandy soil
• Plants lack vigor
• Plants turn yellow by
mid-summer
Soils for Plant Growth
What Would You Do?
• Three-year-old
flower beds
• Annuals and
perennials
• Unsatisfactory
results
• Clay soil
Soils for Plant Growth
What Would You Do?
• Trees and shrubs won’t
grow
• Dead rhododendrons
• Yellowing pin oak
• Plants slowly dying
• Heavy clay soil
Soils for Plant Growth
Questions and Comments