Soils and Nutrition

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Soils and Nutrition

• HORT 411 Nursery Crops

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Today

• Properties of soils
• Identifying nutrient deficiencies
• Container media
• Fertility management

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Properties of soils

• Physical properties
• Texture
• Permeability
• Water holding capacity
• Structure
• Porosity
• Bulk density
• Chemical properties
• Fertility
• Cation exchange capacity
• pH
• Salinity

• Biological Properties
• Soil biota
• Microorganisms

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Soil Management

• Tilling
• Ripping
• Maintain appropriate soil physical properties

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Properties of soils

• Physical properties
• Soil texture affects
• water retention
• aeration
• specific heat capacity
• fertility or cation exchange capacity
• tillage

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Properties of soils

• Physical properties
• Permeability
• the rate at which water moves through the soil
• Water holding capacity
• the ability of a soil to hold water for plant use
• Both are affected by the amount, size, and
  arrangement of pores
• Macropores control a soils permeability and
  aeration
• Micropores are responsible for a soils WHC

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Properties of soils

• Aeration
• Definition
• The process by which air in the soil is replaced
  by air from the atmosphere.
• Soil air mainly composed of
• Oxygen
• Needed for respiration by roots and
  microorganisms
• Carbon dioxide
• Byproduct of respiration
• Reduced aeration is a result of
• Waterlogging
• Soil compaction
• Crusted soils

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Properties of soils

• Bulk density (DB)
• Definition
• The mass of a known volume (including air space)
  of soil
• Compaction leads to an ? in DB
• Soil becomes more dense through a loss of pore
  space
• Measurement
• Soil volume is determined in place
• Dried to a constant weight
• DB soil DW / soil volume
• Causes
• Use of heavy equipment, esp. in wet soils

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Properties of soils

• Bulk density (DB)
• Consequences
• Impeded root penetration
• Reduced water infiltration
• Reduced water availability
• Reduced nutrient availability
• Reduced gas exchange
• Reduced availability of O2
• Greater accumulation of CO2

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Properties of soils

• Bulk density (DB)
• Indiana

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Properties of soils

• Physical properties
• Texture
• Permeability
• Water holding capacity
• Structure
• Porosity
• Bulk density
• Chemical properties
• Fertility
• Cation exchange capacity
• pH
• Salinity

• Biological Properties
• Soil biota
• Microorganisms

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Properties of soils

• Fertility
• Nutrients classified as macro or micro based
  on concentration in plant tissue
• Macronutrients
• N and K most often deficient in low fertility
  soils
• Micronutrients

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Properties of soils

• Methods for determination of soil chemical
  properties
• Saturated media extract (SME)
• Pour-through (PT)
• Typically values are half those of SME values

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Properties of soils

• Chemical properties
• Cation Exchange Capacity (CEC)
• capacity to hold cations
• Silicate and aluminosilicate clay particles are
  negatively charged colloids.
• Cations are bound ionically to the surface of
  these colloid particles.
• CEC is expressed as meq/100 g of soil.
• Cations with higher charge densities, ie, smaller
  cations, will replace larger cations.
• H will displace Ca
• Ca will displace Mg.

Typical CEC values by soil type
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Soil Management

• Cation Exchange Capacity (CEC)
• Definition
• A measure of the total amount of exchangeable
  cations that a soil can hold.

• High in
• Clay
• Organic matter
• Alkaline soils
• Low in
• Sand
• Perlite
• Acid soils

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Soil Management

• Cation Exchange Capacity (CEC)
• Ion attraction to soil depends on
• Ion size
• Number of valence electrons
• Degree of hydration
• Concentration of salts

Na NH4 K Mg Ca H
Increasing attraction to soil
What about anions? PO4- NO3- SO4- Cl-
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Soil Management

• pH
• What is pH?
• What is the optimal pH for plants?
• How does pH affect nutrient availability?
• Most nutrient imbalances are due to pH, not the
  amount of nutrient present.
• Example Hydrangea flower color

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Soil Management

• pH and nutrient availability
• Most nutrients more available at low pH

Most available
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Soil Management

• pH and nutrient availability
• Example Fe and Mn
• Both are available at low pH
• Availability declines with ?pH
• Some Indiana soils are pH 8
• Combination of high pH and acid-loving plants
• Fe or Mn deficiencies
• Problem in oaks in IN (prefer pH of 4.5-6.0)

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Soil Management

• pH and nutrient availability
• Soil pH can be modified
• increase pH
• lime
• lower pH
• sulfur
• Degree of change depends on
• Soil texture
• Organic matter
• For of modifying substance to be used
• Rate of change depends on
• Temperature
• Moisture

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pH and nutrient deficiency

• Modifying soil pH
• Degree of change depends on
• Soil texture
• Organic matter
• Form of modifying substance to be used

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pH and nutrient deficiency

• Modifying soil pH
• For ornamentals in IN soils, we sometimes want to
  ? pH
• Quick fixes
• Aluminum sulfate
• Ammonium sulfate
• Urea
• Longer term
• Sulfate (gypsum)
• Time how long will it take?
• Area how much of the root zone can we actually
  change?

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Soil pH

• Sources of soil acidity
• Hydrolysis of aluminum
• Alumino-silicate clay dissociations
• Organic matter breakdown
• Carbonation
• Nitrification
• Sulfur oxidation

Hydrolysis of aluminum Al3(soln.) H20 ?
Al(OH)2 H Al(OH)2 H20 ? Al(OH)2
H Al(OH)2 H20 ? Al(OH)3 H
Nitrification Nitrosomonas 2 NH4 3O2 ? NO2-
2H2O 4H Nitrobacter 2NO2- O2 ? 2NO3-
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Soil pH

• Neutalizing soil acidity
• Calcium carbonate (lime)
• Magnesium carbonate
• Calcium-magnesiu carbonate
• Calcium oxide (CaO)
• Calcium hydroxide
• Wood ash

Calcium carbonate CaCO3 H ? Ca2
HCO3 HCO3 H ? CO2 H20
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Soil Management

• pH and nutrient availability
• Species dependent

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Plants tolerant of high pH
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Properties of soils

• Physical properties
• Texture
• Permeability
• Water holding capacity
• Structure
• Porosity
• Bulk density
• Chemical properties
• Fertility
• Cation exchange capacity
• pH
• Salinity

• Biological Properties
• Soil biota
• Microorganisms

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Properties of soils

• Roles of OM in soil
• Attracts and holds elements in an available state
• reducing leaching losses
• Binds soil particles into aggregates
• increasing aeration
• increasing capillary water movement
• increasing root penetration
• Increases water-holding capacity

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Properties of soils

• Roles of soil organisms
• fix N2 from air
• mineralization
• form symbiotic relationships with roots
• increased mineral uptake
• create tunnels in soil
• increased aeration, water penetration, etc
• prey on plant pathogens
• produce CO2

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Soil Management

• Soil sterilization
• Steam
• Soil temp 76F
• With steam 180F
• Methyl Bromide
• Exemption ends soon

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Soil Management

• Many nursery practices contribute to loss of soil
  productivity
• Digging
• Erosion
• Clean cultivation
• Working on wet soils

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Soil Management

• Fallow (bare-ground)
• Decrease habitat for pests and diseases
• Cover-crop
• Increase organic
• matter content
• Organic matter added
• Sawdust
• Compost
• Manure

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Container media

• Ideal characteristics
• Free of weeds, pests, and disease
• Heavy enough to avoid tipping over
• Light enough for efficient handling shipping
• Well drained
• High water holding capacity
• Other factors
• Price
• Availability
• Consistency

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Media selection

• Physical properties
• Related to container size
• Air space
• Available water
• Not related to container size
• Porosity
• Bulk density

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Media selection

• Physical properties
• Normal ranges for container media
• Total porosity 50 - 85
• Air space 10 - 30
• Available water 25 - 30
• Bulk density 0.19 - 0.52 g/cc

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Media selection

• Physical properties
• Water holding capacity
• Aeration
• Bulk density
• Chemical properties
• Fertility
• pH
• Cation exchange capacity

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Container media organic amendments

• Peat moss
• Plant material (usually Sphagnum spp.) that has
  decomposed under partial exclusion of oxygen
• High WHC
• High CEC
• Low nutrient levels
• Low pH (3.0 - 4.5)
• Hydrophobic

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Container media organic amendments

• Softwood bark
• Pine bark stripped from trees and screened into
  various sizes. May be fresh, aged, or composted.
• Hardwood bark
• Less acid than softwood bark. May contain
  leachable organic acids (toxic)

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Container media organic amendments

• Sawdust and wood chips
• CN ratio is extremely high and therefore not
  recommended.

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Container media organic amendments

• Manures
• Potentially high in soluble salts
• Fine particle size
• Weed seeds
• Nutrient contribution
• Plant-based composts
• Particle size may be too fine or too large
• Degree of degradation (CN) important

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Container media inorganic amendments

• Perlite
• Silicaceous material
• Volcanic origin
• Improves aeration
• Very low mass
• High water holding capacity
• (3 4 its weight)
• Low cation exchange capacity
• No nutrient content
• Neutral pH

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Container media inorganic amendments

• Vermiculite
• Hydrated Mg-Al-Fe silicate
• Improves aeration
• Low bulk density
• High water holding capacity
• 5 its weight
• High cation exchange capacity
• Neutral pH
• Contains K and Mg

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Stock types
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Container media typical mixes

• Greenhouse
• Commercial (premixed) mixes
• Consistent product quality
• Content the same
• Expensive
• Not tailored to specific plant type
• Custom mixes
• Typically peat, vermiculite, and perlite
• Nursery
• Typically bark, peat, sand, and soil
• Typical recipe
• 80 bark
• 10 peat
• 10 sand

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Media selection

• Composts
• Add CEC and nutrients to substrates
• reduce adding minor nutrients
• provide starter nutrients
• high soluble salts
• Raise pH
• no lime addition necessary
• Lack course particles
• Increase water holding capacity
• Further decomposition is a concern
• Limit to 10-30 container volume

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Goals of Nutrient Management

• Supply adequate amount of nutrients for
• Maintained shoot growth
• Healthy root growth
• Protection from insects disease
• Over-fertilization results in
• Excessive growth
• Increased costs
• Environmental damage

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Factors to consider when developing a
fertilization program

• Nutrient availability
• Relative proportion of nutrients to each other
• Timing of application
• Moisture availability

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How to identify a nutrient deficiency

• Soil and plant tissue test
• Annual growth
• Deficiency symptoms

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Soil Management

• Tests for nutrient status
• Plant tissue tests
• Timing
• Sampling methods
• Soil tests
• Monitor nutrient status
• Adjust fertilizer formulations
• Timing
• Conduct in conjunction with tissue tests
• Water tests
• pH
• Nitrates
• Soluble solids (salts)

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Soil Management

• Tests for nutrient status

• AL Great Lakes Lab, Inc.
• Fort Wayne, IN
• Ag Source Belmond Labs
• Belmond, IA
• Agri Labs, Inc
• Bronson, MI
• Brookside Farms Lab
• New Knoxville, OH
• Cal Mar Soil Testing Lab
• Westerville, OH
• CLC Labs
• Westerville, OH
• Ingrams Soil Testing Center
• Sullivan, IN

• Land O Lakes, Inc.
• Indianapolis, IN
• Midwest Laboratories
• Omaha, NE
• Mowers Soil Testing Plus, Inc
• Toulon, IL
• Spectrum Analytical, Inc
• Washington Courthouse, OH
• Southern Illinois Soil Lab
• Hamel, IL
• United Soils, Inc
• Fairbury, IL
• Waters Agricultural Labs
• Camilla, GA

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• Deficiency symptoms
• Roles of essential nutrients
• Nutrients that are part of carbon compounds
• N, S
• Nutrients that are important in energy storage or
  structural integrity
• P, Si, B
• Nutrients that remain in ionic form
• K, Ca, Mg, Cl, Mn, Na
• Nutrients that are involved in redox reactions
• Fe, Zn, Cu, Ni, Mo

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• Deficiency symptoms - Nutrient mobility
• Highly mobile
• N, P, K, Mg, Zn, Mo
• Deficiencies occur in older leaves
• Immobile
• Ca, S, Fe, B, Cu
• Deficiencies occur in younger leaves

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• Deficiency symptoms Nutrient mobility
• Highly mobile
• N, P, K, Mg, Zn, Mo
• Deficiencies occur in older leaves
• Immobile
• Ca, S, Fe, B, Cu
• Deficiencies occur in younger leaves

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Nitrogen

• Most required nutrient in plants
• Forms
• Nitrate (NO3-)
• Preferred source for plants
• Uptake most rapid in low pH soils
• Ammonium (NH4)
• Uptake most rapid in neutral pH soils
• Uptake of both forms is temperature-dependent

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Urea ((NH2)2CO)
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Nitrogen

• Deficiencies
• required in greatest amounts
• amino acids, nucleic acids, chlorophyll
• symptoms
• Uniform chlorosis
• Small leaves
• Occurs in old leaves

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Nitrogen

• Molybdenum (Mo) is essential for N conversion
  from ammonium to nitrate in plants
• Therefore, Mo deficiency can result in N
  deficiency symptoms
• Especially true in conifers
• Typically found on acid soils
• Treatment
• Granular or foliar sodium molybdate

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Nitrogen

• Which form to apply?
• Decision based on
• Soil pH
• Weather
• Moisture dependence
• Solubility
• Fast or slow release
• Leaching potential
• Other nutrition needs

• Toxicities
• Dry soils
• Cold
• Poorly drained soils

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Nitrogen

• Sources of quick-release N for woodies
• Availability is not dependent on moisture or warm
  temperatures

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Nitrogen

• Sources of urea-N for woodies

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Nitrogen

• Sources of organic N for woodies
• Sources
• Composted leaf litter, animal manures, etc.
• Slow release
• Very dependent on moisture and temperature
• Added benefits
• Improve soil structure
• May provide protection against diseases

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Nitrogen

• Potentially harmful if released into the
  environment
• How do you minimize amount of nitrogen released?
• Timing of application(s)
• Method of application
• Cultural practices
• New methods
• e.g. defoliants
• You MUST understand the physiology of the crops
  you are working with

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Phosphorus

• Deficiencies
• Required in relatively high amounts
• nucleic acids, ATP
• Deficiencies occur on acid soils
• Symptoms
• Small leaves
• Weak, stunted plant
• Bronze to purple tinge
• Occurs in old leaves

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Phosphorus

• Forms
• Inorganic
• Superphosphate (0-20-0)
• Triple superphosphate (0-46-0)
• Phosphoric acid
• Ammonium phosphate (11-48-0)
• Di-ammonium phosphate (18-46-0)
• Organic
• Compost
• Leaf litter
• Bone meal

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Phosphorus

• Application
• Apply prior to planting if possible.
• Phosphorus is available for several years.

Source Smith, 1986
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Phosphorus

• Excessive application
• Results in deficiencies of other nutrients
• Copper, iron, zinc, calcium
• Can leach into ground water

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Potassium

• Deficiencies
• Required in relatively high amounts
• Water uptake, stomatal opening
• Deficiencies in woodies are rare
• Symptoms
• Weak, stunted plant
• More susceptible to disease
• Occurs in old leaves

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Potassium

• Forms
• Inorganic
• Potassium chloride (0-0-60)
• Potassium sulfate (0-0-60)
• Potassium nitrate (13-0-44)
• Organic
• Manure
• Seaweed

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Potassium

• Application
• Apply prior to planting
• Potassium levels may be low at the end of the
  growing season

Source Smith, 1986
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Iron (Fe)

• Most common micronutrient deficiency in woody
  plants
• Most common in high pH soils
• Some species especially susceptible
• Pin oak, white pine, sweet gum
• Loss of roots leads to deficiency
• Some nutrients in excess cause Fe deficiency
• Phosphorus, zinc, manganese, copper
• PFe ratio should be about 291

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Iron (Fe)

• Deficiency treatment options
• Soil treatment
• Typically not practical to modify soil pH for
  trees
• Chelates
• Sequestar 6 Iron chelate, Sequestrene 138
• Usually only last 1 year
• Foliar spray
• Iron chelates or iron sulfate
• Apply early in the season
• Response is quick, but often spotty
• Trunk injection
• Ferric ammonium citrate (iron citrate) or iron
  sulfate
• Apply just after leaf expansion
• Uptake improved if holes are drilled in root
  flares
• Lasts for approximately 2 years

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Iron (Fe)

• Chelates
• Iron application
• Fe supplied as FeSO4 or Fe(NO3)2
• FeOH precipitate forms
• Fe(PO4)2 may also form
• Chelators form soluble complexes
• ionic rather than covalent bonds
• common chelators
• ethylenediaminetetraacetic acid (EDTA)
• diethylenetriaminepentraacetic acid (DTPA)

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Manganese (Mn)

• Also a common micronutrient deficiency in woody
  plants
• Most common in high pH soils
• Some species especially susceptible
• Maples, cherry
• Cold, wet periods
• Can be applied as manganese sulfate (MnSO4)

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• pH and nutrient availability
• Example Fe and Mn
• Both are available at low pH
• Availability declines with ?pH
• Some Indiana soils are pH 8
• Combination of high pH and acid-loving plants
• Fe or Mn deficiencies
• Problem in oaks in IN (prefer pH of 4.5-6.0)

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Fertilizer Application

• Not just amounts, but ratios
• Some elements compete at the root surface

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Timing of Application

• Spring
• Major application
• Have nutrients available before growth begins
• Fall
• Increase N reserves (foliar spray)
• Avoid extremely high applications late in season
• Not effective during or after onset of cold
  weather
• Think about solubility and speed of release

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Timing of Application

• Effect of plant growth stage (trees and shrubs)
• Stage 1 Planting to newly planted
• Approx. 1 lb actual N per 1000 ft2
• Broadcast quick release N do not add to
  planting hole
• Stage 2 Young trees and shrubs
• Rapid growth usually desired
• Approx. 2 to 4 lb actual N per 1000 ft2
• Split applications for plants surrounded by turf
• Stage 3 Mature trees and shrubs
• Growth rate slows
• Goal is maintaining plant health
• Approx. 1 lb actual N per 1000 ft2

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Timing of Application

• Effect of plant phenology
• Roots active in early spring and fall

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Timing of Application

• Effect of soil type
• Sandy soils
• Nutrients in solution and therefore more
  available
• Nutrients move more quickly through soil
• Quick response
• Leaching potential is higher
• Split applications
• Clay soils
• Nutrients more bound to soil particles
• Nutrients move slowly through soil
• Slow response
• Leaching potential is lower
• Split applications not necessary

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Fall Fertilization

• Why?
• Some nutrients limiting at the end of the season.
• Spring rain may leach soil nutrients.
• Optimal timing of spring fertilization is tricky.
• Potential effects
• Increased cold hardiness.
• Increase nutrient reserves to draw upon in
  spring.

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Fall Fertilization

• Which fertilizer to use?
• Based on soil test
• Low in N
• High in K
• Potentially micros as well
• How much?
• Rule of thumb 1 lb per 1000 ft2

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Fall Fertilization

• Nitrogen
• Avoid applying high N fertilizer, even if soil
  test indicates slight deficiency.
• Application can lead to maintained growth and
  decreased cold acclimation.
• Can also create imbalances with other nutrients
  (e.g. K)

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Fall Fertilization

• Potassium
• Low availability in some areas at the end of the
  growing season
• Apply in fall for enhanced spring growth
• Use a potassium source low in nitrogen and
  phosphorus
• 5-3-15, 5-5-30, or 5-0-20
• Apply late Aug to early Sept to allow for uptake
• Application rate of 1 lb K per 1000 ft2
• N is required for efficient uptake of K, so check
  soil tests and apply accordingly

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• Factors affecting plant nutrient uptake
• Nutrient
• availability
• mobility
• competition
• Plant
• species
• cultivar
• phenology
• stress

• Environment
• water
• ionic status
• pH
• temperature