Transcript Environmental Requirements - mr-white-ag

Environmental
Requirements
Original by Linda Rist
Modified by Georgia Agricultural
Education Curriculum Office
July, 2002
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
plowed
depth normally
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. Continued…
–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
results
according to soil test
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
 Boron
-B
 Copper - Cu
 Zinc - Zn
- Mn
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
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,
roots 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% relative humidity (R.H.)
 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
Photosynthesis
 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