Soils and plant nutrients

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Soils and plant nutrients

• Soils and soil texture
• Soil texture triangle
• Plant nutrients
• Major nutrients
• Secondary nutrients
• Minor nutrients
• _________ Exchange Capacity (CEC)
• Soil pH

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Soils

• Consists of a series of layers called _________
• Topsoil (A horizon) upper most layer
• Soils consists of
• Mineral particles determine soil texture
• Organic matter
• Air and ___________
• Soil organisms

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Soil texture - Introduction

• Soil texture coarseness or fineness of soil
• Why is soil texture important?
• It determines
• ____________________ size
• Pore space
• Amount of air (oxygen)
• _________________ flow through soil
• How easily the soil is worked
• _________________ easily worked soil
• Three soil textures (sand, silt, clay)

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Sand texture

• Largest particles
• Size from 0.2mm (finest sand) to 2 mm (coarsest
  sand)
• Warms up and dries early in the spring
• Does not hold water or ________________
• Feels gritty if rubbed between fingers

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Silt texture

• Intermediate particle size
• 0.002 to 0.05 mm
• Often referred to as rock _____________
• Can be transported long distances in water or air
• Feels silky or floury to the touch

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Clay texture

• Smallest particle size
• lt 0.002 mm in size
• Does not drain well
• Slow to warm up
• Difficult to work (not _______________)
• ____________ growth poor due to small spaces
  between particles
• Retains nutrients
• Feels sticky to touch and forms a ribbon

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Soil type

• Most soils are a mixture of different soil
  textures
• Often a soil type will be dominated by a
  particular soil texture
• Example ________________ sand
• Important to know the soil type because it will
  determine the ____________________ practices you
  need to use
• What is the drainage?
• Do soil amendments need to be added?

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Soil texture triangle

• Allows you to know the soil type of your gardens
  soil
• Three axis - clay, ______, sand
• Example 20 clay, 40 silt, and 40 sand is a
  loam soil

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Nutrients needed by plants
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Nutrients needed by plants

• Can divide the nutrients needed by plants into 3
  categories
• Major plant nutrients
• Nutrients needed in largest amounts
• ____________________ plant nutrients
• Nutrients needed in moderate amounts
• Minor nutrients
• Nutrients needed in very small amounts

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Major plant nutrients

• Consist of
• Nitrogen (N)
• ________________ (P)
• Potassium (K) also called Potash
• Major plant nutrients are listed on fertilizer
  bags
• N, P, K
• Form of nutrients will be listed in smaller print

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Nitrogen

• Nitrogen under goes a cycle in environment
• N is essential building block of plants. Used in
• Proteins
• Plant pigments
• _________________
• Secondary metabolites
• Plant hormones (i.e. _____________)
• Needed in largest amounts
• Most N is in atmosphere
• In soil most N is in organic matter
• Unavailable to plants

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Nitrogen

• Plants absorb the nitrate form of N
• The nutrient most likely to be deficient
• Ways nitrogen becomes unavailable to plants
• _______________
• Downwards movement of N and other nutrients in
  the soil solution
• Runoff when bound to clay or organic matter
• Harvest of crops
• Denitrification
• In ___________________ soils, N can be converted
  by microbes into atmospheric N

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Nitrogen

• Nitrogen deficiency
• Symptoms ____________________ of the leaves,
  especially the older leaves
• Treatment apply a material high in N
• Excess nitrogen
• Easy to over apply nitrogen
• Will cause
• ______________ maturity
• Uneven ripening
• Overly succulent _________

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Phosphorous (P)

• Plants use phosphates
• Phosphates can be ____________ pollutants
• Most soils contain large amounts of P but not in
  forms available to the plant
• Functions
• It is important for use and storage of energy
• Stimulates root, fruit, and seed development

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Phosphorous

• Phosphorous deficiency
• Symptoms Slight stunting of the plant, older
  leaves will be _______________, and undeveloped
  root system
• Treatment
• Apply ___________ meal
• Apply a synthetic fertilizer containing a high
  level of P
• Phosphorous does not move much in the soil

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Potassium (K) also known as Potash

• Where did the name potash originate?
• Considered to be in the form of K2O
• Not _______________ readily
• Is essential for synthesis of proteins and
  carbohydrates
• Is needed in higher amounts by root crops
• Organic fertilizers are often low in K

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Potassium

• Potassium deficiency
• Symptoms
• Small inferior flowers and fruits and
  _________________ plants.
• Yellowing along the edges of older leaves
• Leaves become _________________
• Treatment is to apply a fertilizer high in K

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Secondary Nutrients

• Calcium
• Plays an important role in _______ wall
  development
• Calcium deficiency problems
• Calcium deficiency is rare but plants sometimes
  cannot adequately distribute calcium

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Calcium

• Symptoms
• ____________ in lettuce and cabbage
• Blossom-end rot in tomatoes
• Treatment
• There is no immediate cure for calcium
  deficiency problems
• Adding materials high in calcium will not solve
  the problem
• Maintain even watering
• ________________ the plants
• Maintains more even soil moisture

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Secondary Nutrients

• Magnesium
• Magnesium deficiency
• Symptoms yellowing starting between the
  _____________ of the older leaves
• Sulfur
• Generally not a problem
• Used for making soils more ____________ and is
  found in compost and manures

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Micronutrients

• Introduction
• Are needed in very small quantities
• Generally all micronutrients are available in
  _________________ materials you apply to the
  garden
• Best treatment is to prevent the problem from
  occurring in the first place
• Availability is determined by soil _________

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Micronutrients

• Examples of important micronutrients
• Iron needed in synthesis of _____________
• _________
• Boron deficiencies are more likely on
  ________________ soils
• Molybdenum deficiency generally due to acid soil
  conditions

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Cation Exchange Capacity (CEC)

• It is the ability of clay, organic matter, and
  ________________ to attract positive ions
• Clay, organic matter, and humus all have
  ___________ charges on their surfaces
• Most nutrients (P, K, Ca, etc) are _____________
  or have positive charges
• Opposites attract

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Soil pH Acidity and Alkalinity

• What is pH?
• pH is logH
• pH is a scale from 1 to ______
• Why is pH important?
• Because nutrients are more or less available
  depending on the soils pH
• The ideal range is 6.2 to ______

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Soil pH

• Influences disease problems
• Acid soils promote ____________ root disease of
  cabbage
• Adjusting the pH
• ___________ is used to raise the pH
• Sulfur is used to ___________ the pH