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SOIL
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Soil n composed of sand, silt, and clay, organic matter, living organisms, and pore spaces
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Soil n classified according to percentage of sand, silt, and clay they contain.
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Soil Particles n vary greatly in size n sand is the largest n silt - medium n clay - smallest
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Clay n particles hold moisture and plant food elements more effectively than larger particles.
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Soil Profile n consists of 3 basic layers n Topsoil – A horizon n Subsoil – B horizon n soil bedrock – C horizon
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Topsoil n represents depth normally ploughed
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Subsoil n deep rooting plants send roots down into subsoil
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Sandy Soil n silt and clay make up less than 20% by weight n drain well n little water holding capacity
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Clayey Soil n must contain at least 30% clay n holds more moisture than is good for plants n poor drainage
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Loamy Soil n most desirable soil n equal parts sand, silt and clay
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Read page 49 n Answer the questions
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Answers pg 49 1. - B 2. - B 3. - B 4. - C 5. - C 6. - D 7. - C 8. - A 9. - D 10. - A
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Soil Improvement n Drainage – change soil structure –add organic matter to encourage earth worms
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Worms n their tunnels and castings result in better soil structure - aggregation - clinging together
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Drainage n drainage tiles n raise planting beds n ditching between beds
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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
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Sources of O.M. n peat moss n sawdust n mulches - compost or wood chips
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Mulches n placed on the surface to help retain moisture n reduce runoff and evaporation n reduce weeds
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Moisture retention n irrigation
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Fertilizing n fertilize according to soil test results
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Read page 50 – Nutrient status n Answer all questions
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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.
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Nutritional deficiencies n show on leaves of plants n Nitrogen - pale green leaves n Phosphorus - purple color on underside of leaves
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Plant food and fertilizers n divided into two groups n Major elements (macro) n Nitrogen - N n Phosphorus - P n Potassium - K
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minor elements (micro) n Calcium - Ca n Magnesium - mg n Sulfur - S n Iron - Fe
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minor elements (micro) n Manganese - Mn n Boron - B n Copper - Cu n Zinc - Zn
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Plant requirements n large amounts of major elements n relatively small amounts of minor elements
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Soil tests n determine amount of elements needed for various plants.
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Nitrogen n generally purchased in one of four forms n Nitrate of soda n ammonium nitrate n http://www.youtube.com/watch?v=Ekx84- T5GLk&feature=related http://www.youtube.com/watch?v=Ekx84- T5GLk&feature=related
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Nitrogen n ammonium sulfate n urea formaldehyde
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Nitrogen n has most noticeable effect on plants n encourages above ground vegetative growth n regulates use of other elements n http://www.youtube.com/watch?v=N1AVE6- FcAI&feature=related http://www.youtube.com/watch?v=N1AVE6- FcAI&feature=related n http://www.youtube.com/watch?v=m4YToXw724w&fe ature=related http://www.youtube.com/watch?v=m4YToXw724w&fe ature=related n http://www.youtube.com/watch?v=uYaTdC- dCYQ&feature=relmfu http://www.youtube.com/watch?v=uYaTdC- dCYQ&feature=relmfu
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Too much N n lower disease resistance n weaken stem because of long soft growth n lower fruit quality
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Too much N n delay maturity n increase winter damage to plants
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Not enough N n yellow or light green color n stunted root and top growth
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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
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Don’t use excess N n quickly lost through leaching n can damage plants
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Phosphorous n held tightly by soil particles n not easily leached
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Phosphorous n effects plants in several ways n encourage cell division
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Phosphorous n flowers and seeds don’t form without it n hastens maturity, offsetting quick growth caused by N.
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Phosphorous n encourage root growth n makes K more available n increase disease resistance n improves quality of grain, roots and fruit crops
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Phosphorous n container plants can be damaged by excess P n increases soluble salt content of medium n causes dehydration of roots
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Phosphorous n Insufficient P n purple color on underside of leaf n reduced flower fruit and seed production
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Insufficient P n susceptibility to cold injury n susceptibility to plant diseases n poor quality fruit and seeds
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Potassium n modifies both fast, soft growth of N and early maturity of P n is essential
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Potassium n increase disease resistance n encourages healthy root systems n essential for starch formation
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Potassium n development of chlorophyll n efficient use of CO2
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Insufficient K n leaves appear dry and scorched with irregular yellow areas on the surface
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Nutrients NutrientWhy plants need this nutrient NitrogenUsed to make proteins and encourages leaf growth. Important in the process of photosynthesis. PotassiumImportant in the processes of photosynthesis and respiration and with flowering and fruit growth. SulfurUsed in the production of chlorophyll and needed in many proteins. BoronInvolved in the production of proteins and growth hormones and found in some enzymes. CopperOccurs in some enzymes concerned with respiration.
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IronNeeded to make chlorophyll and occurs in some enzymes involved in respiration. CarbonUsed in the processes of photosynthesis, respiration and transpiration. OxygenUsed in the processes of photosynthesis, respiration and transpiration. PhosphorusImportant in the production of flowers and fruit and in the process of photosynthesis. Calcium http://www.youtube.com/watch?v =UpsmJaHFH1g Occurs in the cell walls and required for the development of stem and root tips. MagnesiumUsed in the production of chlorophyll.
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MolybdenumUsed in the chemical reaction to make nitrogen available in the soil from nitrates. ManganeseAids in the production of chlorophyll and occurs in some enzymes. CobaltPresent in some enzymes and required in some growth processes. Hydrogen Used in the processes of photosynthesis, respiration and transpiration. ZincImportant in controlling plant growth.
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Lime n CaCO 3 - Calcium Carbonate n acts as a plant food n affects soil acidity n soil acidity affects availability of plant food elements
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Lime n furnishes Calcium
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pH n measure of acidity or alkalinity n pH scale - runs from 0 - 14 n most plants grow best from 5.6-7.0
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pH n 7.0 is neutral n pH of 7 or above is alkaline or basic n pH below 7 is acidic
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pH n as numbers decrease, solution becomes more acidic. n As numbers increase, solution becomes more basic or alkaline
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pH n if soil is too acidic, lime is added to raise the pH n if soil is too alkaline, sulfur is added
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Above ground environment n temperature n some plants prefer cool weather n some plants prefer warm weather
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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
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Light n must be present before plants can manufacture food n plants vary in light requirement n effects flowering
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Photoperiodism n response to different periods of day and night in terms of growth and maturity
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Photoperiodism n short day plants n chrysanthemum and Christmas Cactus n bloom when days are short and nights are long
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Photoperiodism n long day plants n lettuce and radishes n bloom when days are long and nights are short
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Photoperiodism n day length indifferent n do not depend on length of light or darkness n African Violet and tomato
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Phototropism n plants appear to grow towards the sun or light source
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Humidity n moisture level of the air n most plants grow best in 40- 80% relative humidity (R.H.) n Relative Humidity
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Humidity n too high humidity may cause the spread of fungus diseases
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Plant diseases and Insects n reduce production n lower fruit and vegetable quality
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Gases and Air Particles n CO2 is vital to plants for Photosynthesis n Air pollutants can cause damage
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Air Pollutants n Sulfur Dioxide - SO2 - from burning coal n Carbon Monoxide - CO - exhaust from cars
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Carbon Monoxide n reduces plant growth n can kill plants
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