Soils for Plant Growth

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Soils for Plant Growth

• A Unit of the
• Michigan State University Extension
• Master Gardener Curriculum

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Objectives
Soils for Plant Growth

• Define soil
• Understand its composition
• Understand its physical properties
• Understand its chemical properties
• Identify essential plant nutrients and their
  management

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Objectives
Soils for Plant Growth

• 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

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What Is Soil?
Soils for Plant Growth
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Soils for Plant Growth
What Is Soil?
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Soils for Plant Growth
What Is Soil?
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Soils for Plant Growth
What Is Soil?
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What Is Soil?
Soils for Plant Growth

• Not DIRT!!!
• Precious resource
• Loose, unconsolidated material on the earths
  surface
• Soil scientists definition

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What Is Soil?
Soils for Plant Growth

• A natural body of the earths surface having
  characteristics resulting from climate and living
  organisms acting upon parent material
• as conditioned by slope
• over periods of time

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What Is Soil?
Soils for Plant Growth

• Parent material
• Organisms

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Soils for Plant Growth
What Is Soil?

• Parent material
• Organisms
• Climate
• Topography
• Time

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Soil Provides
Soils for Plant Growth

• Anchorage
• Water
• Air
• Nutrients
• Growth-producing chemical environment

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Soil Is Composed of
Soils for Plant Growth

• Mineral solids
• Organic solids
• Pore spaces

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Ideal Soil Composition
Soils for Plant Growth
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Water
Air
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Mineral
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Organic
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Physical Properties of Soil
Soils for Plant Growth

• Texture
• Structure
• Pore space
• Density
• Temperature

• Color
• Soil organisms
• Organic matter
• Groundwater

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Soil Texture
Soils for Plant Growth

• Sand
• Silt
• Clay

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Soils for Plant Growth
Coarser
Loamy Sand
Sandy Loam
Silt Loam
Clay Loam
Sand
Loam
Clay
Finer
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Soils for Plant Growth
100
90
10
20
80
30
70

clay
40
60
Percent Silt
Percent Clay
50
50
silty clay
sandy clay
60
40
silty clay loam
clay loam
70
30
sandy clay loam
80
20
loam
silt loam
90
sandy loam
10
silt
loamy sand
100
sand
100
90
80
70
60
50
40
30
20
10
Percent Sand
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Soil Structure
Soils for Plant Growth
Loose
Aggregated
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Influence of Soil Structure
Soils for Plant Growth
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Texture Vs Structure
Soils for Plant Growth

• Texture is unchangeable
• Structure can be improved or destroyed

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Compaction
Soils for Plant Growth
Compressed Structure
Good Structure
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Excessive Tillage
Soils for Plant Growth
Too Much Tillage
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Porosity
Soils for Plant Growth

• Porosity Water holding capacity
• Porosity Drainage
• Porosity Aeration
• Porosity Density

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Macro- and Micropores
Soils for Plant Growth
Water-filled microprore
Air-filled macropore
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Soils for Plant Growth
Water Movement
Sand
Loam
Clay
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Soil Density
Soils for Plant Growth
Clay
Sand
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Soil Temperature
Soils for Plant Growth
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Soil Color
Soils for Plant Growth

• Affects soil temperature
• Indicates how much organic matter is present
• Predicts natural drainage conditions

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Topsoil Color
Soils for Plant Growth

• Dark
• High organic matter
• Formed under cool, wet conditions

• Light
• Low organic matter
• Formed under warmer, drier conditions

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Soil Organisms
Soils for Plant Growth

• Bacteria
• Fungi
• Mycorrhizae
• Lichens
• Protozoa
• Invertebrates
• Vertebrates

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Organic Matter Vs Humus
Soils for Plant Growth
decomposes to form
humus
Organic matter

• Highly decomposed
• Stable
• Rich in nitrogen
• Slowly degradable

• Leaves
• Manure
• Grass clippings
• Decomposes rapidly

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Groundwater
Soils for Plant Growth

• Stored in aquifers, water-saturated zones beneath
  the earths surface
• Part of the soil environment if close to the
  surface - high water table
• Easily contaminated

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Points to Remember
Soils for Plant Growth

• Know the physical characteristics of your soil
• Adding organic matter is usually beneficial
• Dont over till
• Dont compact
• Maintain groundcover on slopes
• Avoid bringing in soil of drastically different
  texture

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Chemical Properties of Soil
Soils for Plant Growth
Capacity - Cation Exchange Capacity
CEC
Availability
pH
Intensity - Electroconductivity
EC
Balance - Nutrient ratios
CaMg
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Chemistry 101
Soils for Plant Growth

• 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
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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
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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-
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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-

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Chemistry 101
Soils for Plant Growth

• Unlike charges attract
• Like charges repel

_



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Soils for Plant Growth
Chemical Properties of Soil
Capacity - Cation Exchange Capacity
CEC

• Ca

Soil particle

• K

• Mg

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Cation Exchange Capacity
Soils for Plant Growth
H
K
NH4
K
H
NH4
Ca
Mg
Mg
NH4
Ca
Clay
Humus
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Cation Exchange Capacity
Soils for Plant Growth
CEC 1 - 5 6 - 10 10 20

• Very low with not much clay or humus
• Intermediate loamy texture or sandy with more
  humus
• Progressively more clay and/or humus
• Probably an organic soil

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Soils for Plant Growth
Chemical Properties of Soil
CEC
Availability
pH
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What Is pH and Why Is It Important?
Soils for Plant Growth
H2O H OH-
Remember Everything is dissolved in water
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Soils for Plant Growth
Neutral
Acid
Alkaline
0 1 2 3 4 5 6 7 8 9 10 11
12 13 14
Vinegar
Ammonia
Bleach
Lye
Battery acid
Orange juice
Pure water
Baking soda
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Soils for Plant Growth
Neutral
Acid
Alkaline
0 1 2 3 4 5 6 7 8 9 10 11
12 13 14
Alfalfa
Blueberries
Most plants
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Factors Influencing Soil pH
Soils for Plant Growth

• Components of the soil
• Lime
• Water quality
• Type of nitrogen applied
• Amount of fertilizer
• Crop species

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What Does This Plant Tell You about the pH of the
Soil?
Soils for Plant Growth
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Soils for Plant Growth
What Does This Plant Tell You about the pH of the
Soil?
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Soils for Plant Growth
Chemical Properties of Soil
K
NO3-
Cl-
Ca
Intensity - Electroconductivity
EC
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Soils for Plant Growth
Chemical Properties of Soil
EC
CaMg FeMn KCaMg NK
CEC
pH
Balance - Nutrient ratios
CaMg
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Essential Elements
Soils for Plant Growth
HOPKNS Ca Fe C B Mg Cl Mn Mo Cu Zn!
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Soils for Plant Growth
Essential Elements
HOPKNS Ca Fe C B Mg Cl Mn Mo Cu Zn!
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Soils for Plant Growth
Essential Elements
HOPKNS Ca Fe C B Mg Cl Mn Mo Cu Zn!
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Soils for Plant Growth
Macronutrients

• Nitrogen (N as NO3 and NH4)

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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

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Macronutrients
Soils for Plant Growth

• Nitrogen (N as NO3 and NH4)
• Phosphorous (P)
• Potassium (K)
• Reduced growth / vigor
• Marginal necrosis on older leaves
• Wilt

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Soils for Plant Growth
Macronutrients

• Nitrogen (N as NO3 and NH4)
• Phosphorous (P)
• Potassium (K)
• Magnesium (Mg)
• Calcium (Ca)
• Sulfur (S)

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Soils for Plant Growth
Essential Elements
HOPKNS Ca Fe C B Mg Cl Mn Mo Cu Zn!
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Changing Soil Properties
Soils for Plant Growth

• Changing physical properties
• Bringing in sand / clay / topsoil
• Adding compost
• Changing chemical properties
• Fertilizing
• Adjusting the pH

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Changing Physical Properties
Soils for Plant Growth

• Changing soil texture
• Bringing in sand / clay / topsoil
• Changing soil structure
• Adding compost

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What about Gypsum?
Soils for Plant Growth
Gypsum

• Is it a quick fix for clay soils?

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Fertilizer Composition
Soils for Plant Growth
N
P
N
P
K
K
12-12-12
46-0-0 Urea
0-46-0 Tri-Superphosphate
0-0-60 Muriate of Potash
Inert Material
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Pounds of Actual Nitrogen
Soils for Plant Growth

• 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

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How Much Fertilizer?
Soils for Plant Growth
100 divided by 20 5
20-10-5
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Soils for Plant Growth
How Much Fertilizer?
? divided by ? ?
46-0-0
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Raising Soil pH
Soils for Plant Growth

• Lime
• Dolomitic lime (calcium and magnesium)
• Calcitic lime (calcium only)
• Hydrated lime (calcium only with faster reaction)
• Wood ashes

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Lowering Soil pH
Soils for Plant Growth

• Ammonical nitrogen (ammonium sulfate)
• Iron sulfate
• Acids
• Elemental sulfur

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Why Test Soil?
Soils for Plant Growth

• Basis for using lime and fertilizer
• Diagnosing problems
• Evaluating nutrient balances
• Protecting the environment

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Taking a Soil Sample
Soils for Plant Growth

• When
• Where
• How
• Amount
• Preparing and packaging
• Fill out the form completely

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Interpreting Soil Test Results
Soils for Plant Growth

• Lawns

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Soils for Plant Growth
Interpreting Soil Test Results

• Gardens

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What Is Soil?
Soils for Plant Growth

• A natural body of the earths surface having
  characteristics resulting from climate and living
  organisms acting upon parent material
• as conditioned by slope
• over periods of time

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Horizons
Soils for Plant Growth

• A horizon - topsoil
• E horizon - transition
• B horizon - subsoil
• C horizon - parent material
• R horizon - bedrock

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Whats the Soil Like Where You Live?
Soils for Plant Growth
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What Would You Do?
Soils for Plant Growth

• New home on farmland
• Soil compacted during construction
• Owner wants to establish a lawn

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Soils for Plant Growth
What Would You Do?

• Vegetable garden in full sun
• Sandy soil
• Plants lack vigor
• Plants turn yellow by mid-summer

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Soils for Plant Growth
What Would You Do?

• Three-year-old flower beds
• Annuals and perennials
• Unsatisfactory results
• Clay soil

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Soils for Plant Growth
What Would You Do?

• Trees and shrubs wont grow
• Dead rhododendrons
• Yellowing pin oak
• Plants slowly dying
• Heavy clay soil

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Questions and Comments
Soils for Plant Growth