Environmental Requirements

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Transcript Environmental Requirements

Environmental
Requirements
Soil
composed of sand, silt, and
clay, organic matter, living
organisms, and pore spaces
Soil
classified according to
percentage of sand, silt, and
clay they contain.
Soil Particles
vary greatly in size
sand is the largest
silt - medium
clay - smallest
Clay
particles hold moisture and
plant food elements more
effectively than larger particles.
Soil Profile
consists of 3 basic layers
topsoil
subsoil
soil bedrock
Topsoil
represents depth normally
plowed
Subsoil
deep rooting plants send roots
down into subsoil
Sandy Soil
silt and clay make up less than
20% by weight
drain well
little water holding capacity
Clayey Soil
must contain at least 30% clay
holds more moisture than is
good for plants
poor drainage
Loamy Soil
most desirable soil
equal parts sand, silt and clay
Soil Improvement
Drainage
– change soil structure
– add organic matter to encourage
earth worms
Worms
their tunnels and castings result
in better soil structure aggregation - clinging together
Drainage
drainage tiles
raise planting beds
ditching between beds
Moisture retention
adding organic matter (o.m.)
sources of o.m.
animal manure
green manure - crop grown and
plowed under to improve the
soil
Sources of O.M.
peat moss
sawdust
mulches - compost or wood
chips
Mulches
placed on the surface to help
retain moisture
reduce runoff and evaporation
reduce weeds
Moisture retention
irrigation
Fertilizing
fertilize according to soil test
results
Diseases
plant resistant varieties
chemicals
soil pasteurization
– heat to 180 degrees F for 30
minutes.
Nutritional deficiencies
show on leaves of plants
Nitrogen - pale green leaves
Phosphorus - purple color on
underside of leaves
Planting Media Mixes
Soil less mixes
advantages include : uniformity
- doesn’t vary in pH, fertility or
texture
advantages
sterile
lightweight
good moisture retention and
drainage
free of weed seeds
disadvantages
light weight - pots tip in strong
wind
minor elements are missing
transplants may not adjust well
to new media
Content of mixes
perlite
improve aeration
volcanic origin
Vermiculite
exploded Mica
improves aeration
Plant food and
fertilizers
divided into two groups
Major elements (macro)
Nitrogen - N
Phosphorus - P
Potassium - K
minor elements (micro)
Calcium - Ca
Magnesium - mg
Sulfur - S
Iron - Fe
minor elements (micro)
Manganese - Mn
Boron - B
Copper - Cu
Zinc - Zn
Plant requirements
large amounts of major
elements
relatively small amounts of
minor elements
Commercial fertilizers
shows % or pounds per cwt.
(100#) of the three major
elements in large numbers on
the container or bag.
Commercial fertilizers
5-10-5
5% N, 10% P, 5% K
remaining 80% is filler
NP&K are always listed in that
order.
Soil tests
determine amount of elements
needed for various plants.
Nitrogen
generally purchased in one of
four forms
Nitrate of soda
ammonium nitrate
Nitrogen
ammonium sulfate
urea formaldehyde
Nitrogen
has most noticeable effect on
plants
encourages above ground
vegetative growth
regulates use of other elements
Too much N
lower disease resistance
weaken stem because of long
soft growth
lower fruit quality
Too much N
delay maturity
increase winter damage to
plants
Not enough N
yellow or light green color
stunted root and top growth
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
Don’t use excess N
quickly lost through leaching
can damage plants
Too much N!
Phosphorous
held tightly by soil particles
not easily leached
Phosphorous
effects plants in several ways
encourage cell division
Phosphorous
flowers and seeds don’t form
without it
hastens maturity, offsetting
quick growth caused by N.
Phosphorous
encourage root growth
makes K more available
increase disease resistance
improves quality of grain, root
and fruit crops
Phosphorous
container plants can be
damaged by excess P
increases soluble salt content
of medium
causes dehydration of roots
Phosphorous
Insufficient P
purple color on underside of
leaf
reduced flower fruit and seed
production
Insufficient P
susceptibility to cold injury
susceptibility to plant diseases
poor quality fruit and seeds
Potassium
modifies both fast soft growth
of N and early maturity of P
is essential
Potassium
increase disease resistance
encourages healthy root
systems
essential for starch formation
Potassium
development of chlorophyll
efficient use of CO2
Insufficient K
leaves appear dry and scorched
with irregular yellow areas on
the surface
Lime
CaCO3- Calcium Carbonate
acts as a plant food
affects soil acidity
soil acidity affects availability
of plant food elements
Lime
furnishes Calcium
pH
measure of acidity or alkalinity
pH scale - runs from 0 - 14
most plants grow best from
5.6-7.0
pH
7.0 is neutral
pH of 7 or above is alkaline or
basic
pH below 7 is acidic
pH
as numbers decrease, solution
becomes more acidic.
As numbers increase, solution
becomes more basic or alkaline
pH
if soil is too acidic, lime is
added to raise the pH
if soil is too alkaline, sulfur is
added
Above ground
environment
temperature
some plants prefer cool
weather
some plants prefer warm
weather
Temperature
there are temperatures above
and below which plants stop
growth
generally, plant growth rate
increases as temps increase up
to about 90 degrees
Light
must be present before plants
can manufacture food
plants vary in light requirement
effects flowering
Photoperiodism
response to different periods of
day and night in terms of
growth and maturity
Photoperiodism
short day plants
chrysanthemum and Christmas
Cactus
bloom when days are short and
nights are long
Photoperiodism
long day plants
lettuce and radishes
bloom when days are long and
nights are short
Photoperiodism
day length indifferent
do not depend on length of
light or darkness
African Violet and tomato
Phototropism
plants appear to grow towards
the sun or light source
Humidity
moisture level of the air
most plants grow best in 4080% RH
Relative Humidity
Humidity
too high humidity may cause
the spread of fungus diseases
Plant diseases and
Insects
reduce production
lower fruit and vegetable
quality
Gases and Air Particles
CO2 is vital to plants for Ps
Air pollutants can cause
damage
Air Pollutants
Sulfur Dioxide - SO2 - from
burning coal
Carbon Monoxide - CO exhaust from cars
Carbon Monoxide
reduces plant growth
can kill plants