Environmental Requirements Soil n composed of sand silt

Environmental Requirements

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

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

Soil Particles n vary greatly in size n sand is the largest n silt - medium n clay - smallest

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

Soil Profile n consists of 3 basic layers n topsoil n subsoil n soil bedrock

Topsoil n represents plowed depth normally

Subsoil n deep rooting plants send roots down into subsoil

Sandy Soil n silt and clay make up less than 20% by weight n drain well n little water holding capacity

Clayey Soil n must contain at least 30% clay n holds more moisture than is good for plants n poor drainage

Loamy Soil n most desirable soil n equal parts sand, silt and clay

Soil Improvement n Drainage – change soil structure –add organic matter to encourage earth worms

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

Drainage n drainage tiles n raise planting beds n ditching between beds

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

Sources of O. M. n peat moss n sawdust n mulches - compost or wood chips

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

Moisture retention n irrigation

Fertilizing n fertilize results according to soil test

Diseases n plant resistant varieties n chemicals n soil pasteurization –heat to 180 degrees F for 30 minutes.

Nutritional deficiencies n show on leaves of plants n Nitrogen - pale green leaves n Phosphorus - purple color on underside of leaves

Planting Media Mixes n Soil less mixes n advantages include : uniformity - doesn’t vary in p. H, fertility or texture

advantages n sterile n lightweight n good moisture retention and drainage n fee of weed seeds

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

Content of mixes n perlite n improve aeration n volcanic origin

Vermiculite n exploded Mica n improves aeration

Plant food and fertilizers n divided into two groups n Major elements (macro) n Nitrogen - N n Phosphorus - P n Potassium - K

minor elements (micro) n Calcium - Ca n Magnesium - mg n Sulfur - S n Iron - Fe

minor elements (micro) n Manganese n Boron -B n Copper - Cu n Zinc - Zn - Mn

Plant requirements n large amounts of major elements n relatively small amounts of minor elements

Commercial fertilizers n shows % or pounds per cwt. (100#) of the three major elements in large numbers on the container or bag.

Commercial fertilizers n 5 -10 -5 n 5% N, 10% P, 5% K n remaining 80% is filler n NP&K are always listed in that order.

Soil tests n determine amount of elements needed for various plants.

Nitrogen n generally purchased in one of four forms n Nitrate of soda n ammonium nitrate

Nitrogen n ammonium sulfate n urea formaldehyde

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

Too much N n lower disease resistance n weaken stem because of long soft growth n lower fruit quality

Too much N n delay maturity n increase winter damage to plants

Not enough N n yellow or light green color n stunted root and top growth

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

Don’t use excess N n quickly lost through leaching n can damage plants

Phosphorous n held tightly by soil particles n not easily leached

Phosphorous n effects plants in several ways n encourage cell division

Phosphorous n flowers and seeds don’t form without it n hastens maturity, offsetting quick growth caused by N.

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

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

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

Insufficient P n susceptibility to cold injury n susceptibility to plant diseases n poor quality fruit and seeds

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

Potassium n increase disease resistance n encourages healthy root systems n essential for starch formation

Potassium n development of chlorophyll n efficient use of CO 2

Insufficient K n leaves appear dry and scorched with irregular yellow areas on the surface

Lime n Ca. CO 3 - Calcium Carbonate n acts as a plant food n affects soil acidity n soil acidity affects availability of plant food elements

Lime n furnishes Calcium

p. H n measure of acidity or alkalinity n p. H scale - runs from 0 - 14 n most plants grow best from 5. 6 -7. 0

p. H n 7. 0 is neutral n p. H of 7 or above is alkaline or basic n p. H below 7 is acidic

p. H n as numbers decrease, solution becomes more acidic. n As numbers increase, solution becomes more basic or alkaline

p. H n if soil is too acidic, lime is added to raise the p. H n if soil is too alkaline, sulfur is added

Above ground environment n temperature n some plants prefer cool weather n some plants prefer warm weather

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

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

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

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

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

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

Phototropism n plants appear to grow towards the sun or light source

Humidity n moisture level of the air n most plants grow best in 4080% RH n Relative Humidity

Humidity n too high humidity may cause the spread of fungus diseases

Plant diseases and Insects n reduce production n lower fruit and vegetable quality

Gases and Air Particles n CO 2 is vital to plants for Ps n Air pollutants can cause damage

Air Pollutants n Sulfur Dioxide - SO 2 - from burning coal n Carbon Monoxide - CO exhaust from cars

Carbon Monoxide n reduces plant growth n can kill plants