Soils and Plant Nutrition Master Gardener Class

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Soils and Plant NutritionMaster Gardener Class
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What is Soil?
Soil is the medium in which plants grow - the
basis for plant growth.
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Four Major Components of Soil

• Sand
• Silt
• Clay

Air
20-30
Mineral
45-48
Water
20-30
Organic Matter
2-5
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Soil Components
Sand 2.0 to 0.05mm Silt 0.05 to
0.002mm Clay less than 0.002mm
Mineral
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The proportion of sand, silt and clay determine a
soils texture.
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Soil texture determines a soils water-holding
capacity
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Relationship Between Soil Texture and Water
Availability
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Five Things Organic Matter Does for Soil

• Improves the soils physical condition.
• Supplies plant nutrients.
• Increases water infiltration.
• Helps decrease erosion.
• Improves soil tilth (the soils ability to resist
  compaction).
• Basically natures way of recycling!

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The Ideal Soilfor Crop Production

• Medium texture and organic matter for air and
  water movement
• Sufficient clay to hold soil moisture reserves
• Deep, permeable subsoil with adequate fertility
  levels
• Environment for roots to go deep for moisture and
  nutrients

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Soil Depth InfluencesRelative Productivity
Soil depth usable Relative by roots,
ft. productivity,
1 35 2 60 3 75 4 85 5 95 6 100
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Soil Slope AffectsRelative Productivity
Relative productivity,
Soil slope, Not easily eroded Easily eroded
0-1 100 95 1-3 90 75 3-5 80 50 5-8 60 30
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The smallest particles of soil are called
colloids. Colloids have a negative charge so
they attract positively charged particles.
Colloids repel other negatively charged particles
- like a magnet.
An element or group of elements with an
electrical charge is called an ion. Ions with
negative charges are called anions. Ions with
positive charges are called cations.
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Cation Exchange Capacity
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Plant Nutrients
C HOPKNS CaFe Mg B Mn Cu Zn Mo Cl
See Hopkins Cafe Managed By My Cousin Mo Clay
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Carbon - Hydrogen - Oxygen The three most
abundant elements - plants obtain them from water
and air. These three elements make up more than
94 of plant dry tissue. The remaining 13
elements make up less than 6 of plant dry tissue.
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Macronutrients
Manganese Iron Boron Zinc Copper Molybdenum Chlori
ne
Nitrogen Phosphorus Potassium Sulfur Calcium Magne
sium
Micronutrients
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Roots contact onlya small percentageof
available nutrients
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Nitrogen . . . (N)

• A nitrogen deficiency most limits plant growth.
• Provides a visual green response in plants.
• Plants use large amounts of nitrogen.
• Necessary for the production and transfer of
  energy - photosynthesis.
• Stimulates plant growth.
• Increases seed and fruit yield.
• Improves the quality of leaf and forage crops.
• Present in the soil in three forms.

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• Nitrogen is present in the soil in three major
  forms
• Organic
• Inorganic
• Elemental

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The Nitrogen Cycle
Atmospheric nitrogen
Industrial fixation (commercial fertilizers)
Atmospheric fixation and deposition
Crop harvest
Animal manures and biosolids
Volatilization
Plant residues
Runoff and erosion
Biological fixation by legume plants
Plant uptake
Denitrification
Organic nitrogen
Nitrate (NO3)
Ammonium (NH4)
-
Immobilization

Leaching
Mineralization
Component
Input to soil
Loss from soil
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Nitrogen Deficiency
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Phosphorus . . . (P)

• Also an essential part of photosynthesis.
• Responsible for utilization of starch and sugar.
• Cell nucleus formation.
• Cell division and multiplication.
• Cell organization.
• Transfer of heredity.

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Phosphorus Cycle
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Phosphorus Deficiency
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Potassium . . . (K)

• After nitrogen, plants use the largest amount of
  potassium.
• Plays an essential role in the metabolic process
  of plants.
• Plays a role in raising the disease resistance of
  many plant species.

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How Potassium Moves in Soil
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Potassium Deficiency
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Calcium . . . (Ca)

• An essential part of the wall structure and
  strength of plant cells.
• Provides for normal transport and retention of
  other elements.
• Does not move in plant, deficiency develops in
  new leaves
• Counteracts the effects of alkali salts and
  organic acids within the plant.

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Magnesium . . . (Mg)

• Is essential for photosynthesis.
• Makes up a part of the chlorophyll in green
  plants.
• Helps activate plant enzymes needed for plant
  growth.
• Dolomitic lime and epsom salts contain Magnesium

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Magnesium Deficiency
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Sulfur . . . (S)

• Activates plant enzymes.
• Is required for nodulation and nitrogen fixation
  of legumes.
• Present in glycosides which give the
  characteristic odors and flavors of mustard,
  onion and garlic.

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Soil organic matter is a majorsource of S
S
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Manganese . . . (Mn)

• Activates plant enzymes.
• May substitute for magnesium

Iron . . . (Fe)

• Essential for the synthesis of chlorophyll.
• Symptoms include chlorosis between the veins with
  green veins

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Copper . . . (Cu)

• Essential for plant growth.
• Activates many plant enzymes.

Zinc . . . (Zn)

• Regulates plant growth by controlling the
  synthesis of indoleacetic acid.
• Activates plant enzymes.

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Boron . . . (B)

• Regulates the metabolism of carbohydrates in
  plants.

Molybdenum . . . (Mo)

• Required in tiny amounts.

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MicronutrientsARE NOTmiracle workers
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Nutrient Deficiencies

• A note about nutrient deficiencies
• While many deficiencies show specific symptoms
  this is an inexact science at best.
• Many of the symptoms overlap so the only way to
  be sure is with a combination of tissue analysis
  and soil sampling.

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Nutrient Deficiency Symptoms
Nutrient Position on plant Chlorosis Leaf margin necrosis? Color and leaf shape
N All leaves Yes No Yellowing of leaves and leaf veins
P Older leaves No No Purplish patches
K Older leaves Yes Yes Yellow patches
Mg Older leaves Yes No Yellow patches
Ca Young leaves Yes No Yellow leaves
S Young leaves Yes No Yellow leaves
Mn, Fe Young leaves Yes No Interveinal chlorosis
B, Zn, Cu, Mo Young leaves - - Deformed leaves
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Soil pH is a measure of the hydrogen ion
concentration in the soil.
Buffer pH is the soils ability to resist changes
in pH.
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pH Units
Optimum pH for most plants 5.5 to 6.5
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Factors in Addition to Soil pH Which Influence
the Frequency of Liming

• Soil texture
• Rate of N fertilization
• Rate of crop removal of Ca and Mg
• Amount of lime applied
• pH range desired
• Tillage system
• Irrigated crops

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Why Acid Soils Should Be Limed

• Increases CEC in variable charge soils
• Increases availability of several nutrients
• Supplies Ca and Mg to plants
• Improves symbiotic N fixation in legumes
• Improve crop yields

• Reduces Al and other metal toxicities
• Improves the physical condition of the soil
• Stimulates microbial activity in the soil

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Soil Acidity Affects Plant Growth

• Aluminum, Fe and Mn can reach toxic levels
  because of increased solubilities in acid soils
• Reduced activity of organisms responsible for the
  breakdown (mineralization) of organic matter
• Possible Ca deficiency . . . but most likely a Mg
  deficiency

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Soil Acidity Affects Plant Growth

• The performance of soil-applied herbicides can be
  adversely affected
• Reduced activity of symbiotic N fixing bacteria
• Clay soils high in acidity are less highly
  aggregated
• Availability of nutrients such as P, K and Mo is
  reduced
• Tendency for K to leach is increased

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How Lime Reduces Soil Acidity

• Ca2 ions from aglime replace Al3 at the
  exchange sites. The Al3 reacts with water
  releasing H
• Carbonate ions (CO32-) from aglime react in the
  soil solution, creating excess OH- (hydroxyl)
  ions which combine with H ions forming water
• The pH increases because the acidity source (H)
  has been reduced

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Liming Materials

• Calcitic Lime
• Dolomitic Lime
• Hydrated Lime
• (Use 75 of the above recommended amount)
• Wood Ashes
• (Use with caution!)

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Relative Neutralizing Values of Some Common
Liming Materials
Relative Liming neutralizing material value,
Relative Liming neutralizing material value,
Calcium carbonate 100 Dolomitic
lime 95-108 Calcitic lime 85-100 Baked oyster
shells 80-90 Marl 50-90 Burned lime 150-175
Burned oyster shells 90-110 Hydrated
lime 120-135 Basic slag 50-70 Wood
ashes 40-80 Gypsum None By-products Variable
Relative neutralizing value is used
interchangeably here with calcium carbonate
equivalent
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Particle SizeDetermines Lime Reactivity
Lime reacted in 1 to 3 years,
Finer particle size (logarithmic scale of mesh
size)
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For best results, apply lime well ahead of
planting to allow sufficient time to neutralize
soil acidity
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Fertilizer grade (or analysis) refers to how much
of an element there is in a fertilizer based on
percentage by weight.
Fertilizer ratio describes the relative
proportions of N-P-K in a fertilizer.
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Fertilizer is referred to as

• Complete when it contains all three major plant
  nutrients.
• Incomplete when it lacks one of the major plant
  nutrients.
• Balanced when it contains equal amounts of N-P-K.
• Premium refers to fertilizers that contain the
  minor elements
• Slow release refers to fertilizers that release
  the elements slowly over time

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Lets Do Some MATH

• Many fertilizer recommendation come as pounds of
  (insert element) per 1000 square feet.
• If you add that much product you will NOT get the
  right amount because the product contains only a
  percentage of the element.
• So now what do you do?

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To determine the amount of ammonium sulfate a
5,000-sq ft lawn needs if the lawn requires one
lb of nitrogen per 1,000 sq ft...

• Lawn 5,000 sq. ft.
• Fertilizer Ammonium sulfate (21-0-0)
• Rate of Application 1lb of nitrogen per 1,000
  sq. ft.
• Ammonium sulfate is 21 nitrogen.
• 21 is the same as 0.21 or 21/100.
• This means for every 100 lb. of fertilizer
  there are 21 lb. of nitrogen.
• We need 1 lb of nitrogen for every 1,000 sq.
  ft. Using proportions, we can calculate the
  amount of ammonium sulfate needed to get 1 lb of
  N. X represents the unknown amount being
  calculated.

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Tims Method
To get the right amount of product take the
constant supplied on the right and divide by the
analysis of the element you want.

• ½ lb/1000 ft2 50
• 1 lb/1000 ft2 100
• 1.5 lb/1000 ft2 150
• 2 lb/1000 ft2 200
• 2.5 lb/1000 ft2 250
• See the pattern?

For the example to apply 1 lb of nitrogen /1000
ft2 using 21-0-0. 100/21 4.76 lbs of 21-0-0
per 1000 ft2.
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How much lime and fertilizer should I add to my
garden?
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Soil Test
Soil Test
Soil Test
Soil Test
Soil Test
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Soil testing is essential to applying the correct
fertilizer and Lime!
Adding fertilizer to the soil without testing is
like baking a cake without reading the recipe or
measuring the ingredients
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The greatest potentialfor error in soil
testingis in taking the sample
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A good sample is critical to getting a good soil
analysis!
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Sampling for Home Gardens and Lawns

• Consider different soils and management
  situations that need to be sampled

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Plant analysis and soil testing go hand-in-hand
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Soil Testing vs. Plant Analysis

• Soil testing and plant analysis are
  complementary, but very different
• Soil tests predict nutrient availability
• Plant analysis assesses nutrient uptake
• Soil tests are not always good predictors of
  nutrients that leach easily, i.e. N or S
• Plant analysis is a better tool to assess some
  micronutrients, e.g. B, Fe, Mo

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Lets Review

• To a horticulturist what is soil?
• What is organic matter and what does it do for
  the soil?
• What is pH? What is buffer pH?
• How can I KNOW how much lime and fertilizer to
  add?

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Other Recommended InformationFollow the Links

• Bob Lipperts Soil Page
• Indoor plants
• Fertilizing Lawns
• Mulch
• Fertilizing Trees
• Fertilizing Vegetables

• Home and Garden Information Center (HGIC)
• Soil testing
• Changing the pH of your soil
• Fertilizers
• Composting

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• www.clemson.edu/sandhill
• On the left you will see a link to the South
  Carolina Master Gardener Program.
• This program is available under both powerpoint
  presentations and Electronic Training

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Credits

• I am not a soil scientist so much of this was
  taken from several sources. Some of the
  following are sources Ive stolen this
  information from. Thanks to all who had a part.

• South Carolina Master Gardener Manual
• Home and Garden Information Center
  (http//hgic.clemson.edu)
• Bob Lipperts Powerpoint (Clemson University)
  Slide Presentation
• Michelle Clarks (Richland County Master
  Gardener) MG Slide Presentation
• Brian Smiths (Charleston County Extension Agent)
  COTS Slide Presentation

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• This concludes our lesson.

If you have questions feel free to email me at
rdncn_at_clemson.edu