Environmental Requirements

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Environmental Requirements
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Soil

• composed of sand, silt, and clay, organic matter,
  living organisms, and pore spaces

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Soil

• classified according to percentage of sand, silt,
  and clay they contain.

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Soil Particles

• vary greatly in size
• sand is the largest
• silt - medium
• clay - smallest

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Clay

• particles hold moisture and plant food elements
  more effectively than larger particles.

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Soil Profile

• consists of 3 basic layers
• topsoil
• subsoil
• soil bedrock

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Topsoil

• represents depth normally plowed

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Subsoil

• deep rooting plants send roots down into subsoil

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Sandy Soil

• silt and clay make up less than 20 by weight
• drain well
• little water holding capacity

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Clayey Soil

• must contain at least 30 clay
• holds more moisture than is good for plants
• poor drainage

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Loamy Soil

• most desirable soil
• equal parts sand, silt and clay

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Soil Improvement

• Drainage
• change soil structure
• add organic matter to encourage earth worms

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Worms

• their tunnels and castings result in better soil
  structure - aggregation - clinging together

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Drainage

• drainage tiles
• raise planting beds
• ditching between beds

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Moisture retention

• adding organic matter (o.m.)
• sources of o.m.
• animal manure
• green manure - crop grown and plowed under to
  improve the soil

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Sources of O.M.

• peat moss
• sawdust
• mulches - compost or wood chips

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Mulches

• placed on the surface to help retain moisture
• reduce runoff and evaporation
• reduce weeds

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Moisture retention

• irrigation

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Fertilizing

• fertilize according to soil test results

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Diseases

• plant resistant varieties
• chemicals
• soil pasteurization
• heat to 180 degrees F for 30 minutes.

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Nutritional deficiencies

• show on leaves of plants
• Nitrogen - pale green leaves
• Phosphorus - purple color on underside of leaves

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Planting Media Mixes

• Soil less mixes
• advantages include uniformity - doesnt vary in
  pH, fertility or texture

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advantages

• sterile
• lightweight
• good moisture retention and drainage
• fee of weed seeds

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disadvantages

• light weight - pots tip in strong wind
• minor elements are missing
• transplants may not adjust well to new media

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Content of mixes

• perlite
• improve aeration
• volcanic origin

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Vermiculite

• exploded Mica
• improves aeration

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Plant food and fertilizers

• divided into two groups
• Major elements (macro)
• Nitrogen - N
• Phosphorus - P
• Potassium - K

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minor elements (micro)

• Calcium - Ca
• Magnesium - mg
• Sulfur - S
• Iron - Fe

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minor elements (micro)

• Manganese - Mn
• Boron - B
• Copper - Cu
• Zinc - Zn

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Plant requirements

• large amounts of major elements
• relatively small amounts of minor elements

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Commercial fertilizers

• shows or pounds per cwt. (100) of the three
  major elements in large numbers on the container
  or bag.

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Commercial fertilizers

• 5-10-5
• 5 N, 10 P, 5 K
• remaining 80 is filler
• NPK are always listed in that order.

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Soil tests

• determine amount of elements needed for various
  plants.

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Nitrogen

• generally purchased in one of four forms
• Nitrate of soda
• ammonium nitrate

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Nitrogen

• ammonium sulfate
• urea formaldehyde

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Nitrogen

• has most noticeable effect on plants
• encourages above ground vegetative growth
• regulates use of other elements

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Too much N

• lower disease resistance
• weaken stem because of long soft growth
• lower fruit quality

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Too much N

• delay maturity
• increase winter damage to plants

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Not enough N

• yellow or light green color
• stunted root and top growth

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N lost easily from soil

• leaching - being filtered down through soil with
  water
• not held by soil particles, dissolved in water
• O.M. holds insoluble N for slow release

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Dont use excess N

• quickly lost through leaching
• can damage plants

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Phosphorous

• held tightly by soil particles
• not easily leached

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Phosphorous

• effects plants in several ways
• encourage cell division

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Phosphorous

• flowers and seeds dont form without it
• hastens maturity, offsetting quick growth caused
  by N.

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Phosphorous

• encourage root growth
• makes K more available
• increase disease resistance
• improves quality of grain, root and fruit crops

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Phosphorous

• container plants can be damaged by excess P
• increases soluble salt content of medium
• causes dehydration of roots

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Phosphorous

• Insufficient P
• purple color on underside of leaf
• reduced flower fruit and seed production

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Insufficient P

• susceptibility to cold injury
• susceptibility to plant diseases
• poor quality fruit and seeds

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Potassium

• modifies both fast soft growth of N and early
  maturity of P
• is essential

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Potassium

• increase disease resistance
• encourages healthy root systems
• essential for starch formation

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Potassium

• development of chlorophyll
• efficient use of CO2

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Insufficient K

• leaves appear dry and scorched with irregular
  yellow areas on the surface

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Lime

• CaCO3- Calcium Carbonate
• acts as a plant food
• affects soil acidity
• soil acidity affects availability of plant food
  elements

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Lime

• furnishes Calcium

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pH

• measure of acidity or alkalinity
• pH scale - runs from 0 - 14
• most plants grow best from 5.6-7.0

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pH

• 7.0 is neutral
• pH of 7 or above is alkaline or basic
• pH below 7 is acidic

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pH

• as numbers decrease, solution becomes more
  acidic.
• As numbers increase, solution becomes more basic
  or alkaline

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pH

• if soil is too acidic, lime is added to raise the
  pH
• if soil is too alkaline, sulfur is added

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Above ground environment

• temperature
• some plants prefer cool weather
• some plants prefer warm weather

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Temperature

• there are temperatures above and below which
  plants stop growth
• generally, plant growth rate increases as temps
  increase up to about 90 degrees

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Light

• must be present before plants can manufacture
  food
• plants vary in light requirement
• effects flowering

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Photoperiodism

• response to different periods of day and night in
  terms of growth and maturity

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Photoperiodism

• short day plants
• chrysanthemum and Christmas Cactus
• bloom when days are short and nights are long

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Photoperiodism

• long day plants
• lettuce and radishes
• bloom when days are long and nights are short

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Photoperiodism

• day length indifferent
• do not depend on length of light or darkness
• African Violet and tomato

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Phototropism

• plants appear to grow towards the sun or light
  source

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Humidity

• moisture level of the air
• most plants grow best in 40-80 RH
• Relative Humidity

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Humidity

• too high humidity may cause the spread of fungus
  diseases

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Plant diseases and Insects

• reduce production
• lower fruit and vegetable quality

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Gases and Air Particles

• CO2 is vital to plants for Ps
• Air pollutants can cause damage

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Air Pollutants

• Sulfur Dioxide - SO2 - from burning coal
• Carbon Monoxide - CO - exhaust from cars

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Carbon Monoxide

• reduces plant growth
• can kill plants