SOIL

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 – A horizon Subsoil – B horizon soil bedrock – C horizon

Topsoil

represents depth normally ploughed

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

Read page 49

Answer the questions

Answers pg 49

1. - B2. - B3. - B4. - C5. - C6. - D7. - C8. - A9. - D10. - A

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

Read page 50 – Nutrient status

Answer all questions

Answers for page 50

1. They are required by plants in relatively large quantities.

2. They are only needed in small amounts. Too much could cause toxicity problems or nutrient imbalance.

3. Sandy soils allow water to percolate readily because of the large macropore space. The water takes dissolved nutrients with it. Clay soils do not drain easily so nutrients are retained.

4. Small clay particles means a much larger surface area than sand particles so therefore release more nutrients from that large surface area.

Nutritional deficiencies

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

underside of leaves

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

Soil tests

determine amount of elements needed for various plants.

Nitrogen generally purchased in one of four forms Nitrate of soda ammonium nitrate http://www.youtube.com/watch?v=Ekx84-T5GLk&feat

ure=related

Nitrogen

ammonium sulfate urea formaldehyde

Nitrogen has most noticeable effect on plants encourages above ground vegetative growth regulates use of other elements http://www.youtube.com/watch?v=N1AVE6-FcAI&feat

ure=related http://www.youtube.com/watch?v=m4YToXw724w&fe

ature=related http://www.youtube.com/watch?v=uYaTdC-dCYQ&fe

ature=relmfu

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

NutrientsNutrient Why plants need this

nutrientNitrogen Used to make proteins and encourages leaf

growth. Important in the process of photosynthesis.

Potassium Important in the processes of photosynthesis and respiration and with flowering and fruit growth.

Sulfur Used in the production of chlorophyll and needed in many proteins.

Boron Involved in the production of proteins and growth hormones and found in some enzymes.

Copper Occurs in some enzymes concerned with respiration.

Iron Needed to make chlorophyll and occurs in some enzymes

involved in respiration.Carbon Used in the processes of

photosynthesis, respiration and transpiration.

Oxygen Used in the processes of photosynthesis, respiration and transpiration.

Phosphorus Important in the production of flowers and fruit and in the process of photosynthesis.

Calciumhttp://www.youtube.com/watch?v=UpsmJaHFH1g

Occurs in the cell walls and required for the development of stem and root tips.

Magnesium Used in the production of chlorophyll.

Molybdenum Used in the chemical reaction to make nitrogen available in the soil from nitrates.

Manganese Aids in the production of chlorophyll and occurs in some enzymes.

Cobalt Present in some enzymes and required in some growth processes.

Hydrogen Used in the processes of photosynthesis, respiration and transpiration.

Zinc Important in controlling plant growth.

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 40-

80% 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