Mineral Nutrition A discussion in Chapter 5

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Mineral NutritionA discussion in Chapter 5

• Are Plants What They Eat?
• or
• What is Plant Food?

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Sixteen essential elements

• Carbon, Hydrogen, Oxygen
• Nitrogen, Phosphorus, Potassium
• Ca Calcium, Mg Magnesium, Sulfur
• Fe Iron, Mn Manganese, Mo Molybdenum
• Cu Copper, Boron, Zn Zinc
• Cl Chlorine
• C Hopkins CaFe, Mg B Mn CuZn, Cl Mo

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Essential Elements

• CHO come from air and water
• All the rest come into plants as dissolved
  solutes in soil water
• Not only must they be in the soil, they must also
  exist in a form usable to plants
• Nutrient usage in plants is categorized by the
  relative amounts used in plants
• Macronutrients
• Micronutrients

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Primary Macronutrients

• Nutrients used in largest amounts
• Nitrogen
• Phosphorus
• Potassium

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Secondary Macronutrients

• Used in lesser amounts than primary, but still a
  lot more than micronutrients
• Calcium
• Magnesium
• Sulfur

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Micronutrients

• Minerals used in much smaller amounts
• Iron, Manganese, Molybdenum
• Copper, Boron, Zinc
• Chlorine

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Availability by pH levels
All nutrient forms are affected by soil pH, but
especially the micronutrients. This is why we
often have iron-deficient plants in the West.
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Nitrogen

• Can cause rapid vegetative growth
• Fixed by bacteria on legume plants
• Absorbed as NO3-, NH4, NH2
• Is easily leached from soils
• Especially sandy soil

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N Fertilizer composition and effect on soil pH
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Phosphorus

• Not very soluble in soil water
• Does not leach
• Deficiencies show up as exceptionally dark green
  or purple leaves
• Flowering, fruiting, root development, disease
  resistance

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Potassium

• Easily leached
• Important in stomata opening and closing, water
  retention, starch formation, chlorophyll
  formation
• Deficiency results in stunted plants, older
  leaves may wilt, intervenal chlorosis begins at
  base

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Iron

• Often deficient in plants grown on alkaline soils
• Not due to lack of Fe in soil, but unavailable
  form
• Intravenous yellowing progressing to white
  foliage
• Many micro fertilizers are formulated as
  chelates

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Chelate

• Greek, meaning claw
• Large organic molecules that hold specific
  cations allowing them to be absorbed and used by
  plants
• Chelates hold Fe, Mn, Zn, and S and prevent them
  from reacting with inorganic anions
• Sequestering agents

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Fertilizers

• Divided into 2 common types
• Organic
• Inorganic

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Organic Fertilizers

• Derived from decomposition of animal wastes or
  plant products
• Also act as soil amendments or conditioners
• Nutrients are released slowly through
  decomposition
• Slow and unreliable in cold soil
• Expensive for the amount of nutrients they
  actually contain

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Inorganic Fertilizers

• Come from mined and manufactured raw materials
• Much more concentrated than Organics
• Can be formulated as fast-release or slow-release
• As far as N goes, most plants use the same form
  (NO3-), regardless of how it gets there
• Can cause rapid depletion of soil OM

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Fertilizer Forms

• Liquids
• Salty so they dissolve in water
• Sprayed on root zone or as a foliar application
• Have high tendency to burn plants
• Are usually short-lived
• Granules
• Most common form
• Heavy pellets dont drift too far
• Can be slow-release

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Fertilizer Forms

• Tablets and Spikes
• Large compressed items that are pushed into the
  soil or placed in a hole
• Expensive for the amount of nutrient they contain
• Release nutrients very slowly over time
• Several months to more than a year

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Purchase

• Many factors exist when choosing a fertilizer to
  purchase
• Slow or fast release
• Organic or inorganic
• Liquid or solid
• Analysis
• Price

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Analysis

• Is a statement of the type and quantity of
  nutrients, and must be included on every package
• The standard statement form is 3 numbers
  separated by hyphens on the bag
• 15-5-15 for example
• The numbers give N, P as P2O5, and K as K2O

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Analysis

• Fertilizers are also grouped based on relative
  amounts of N, P, and K
• Balanced 10-10-10
• Complete 20-8-16
• Single Element 21-0-0

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Application Methods

• Topdressing
• Pre-plant incorporation
• Sidedressing
• Needle Feeding
• Drilled-hole
• Foliar

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Mineral Nutrition _at_ Home

• Macronutrients
• Nitrogen will be needed by turf, flowers, shrubs,
  trees, and the garden, add yearly in early spring
  as roots start to grow
• For turf two applications - early spring and
  early fall
• Use residual acid form - ammonium
  sulfate

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Mineral Nutrition _at_ Home

• Macronutrients
• Phosphorus may be needed every 3 - 5 years for
  turf, flowerbeds, shrubs, trees and gardens
• Potassium will generally not be needed. There is
  a sufficient supply in Utah soils and Utah waters
  are high in potassium

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Mineral Nutrition _at_ Home

• Secondary mineral nutrients are usually not
  needed
• Calcium
  Magnesium
  Sulfur

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Mineral Nutrition _at_ Home

• Micronutrients
• Iron
• Manganese
• Zinc
• Look for early signs of deficiencies
• Test with chelated materials applied to the
  foliage to determine needs