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

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 40- 80% 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