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Transcript
SOIL • Medium: The soil mixture is the plant’s source for food, water, and support ▫ The soil mix will have effect on the health, vitality, and appearance of a plant or crop SOIL FORMATION • Begins as rock that is broken into smaller particles ▫ Snow, ice, wind, and rain • Parent material: The original rocky material before weathering has taken place • Lower plant forms such as lichens, moss, and fungi grow on rock matter • Organic matter: The decay of plants and animals which is essential for soil formation WEATHERING • Changes the consistency, chemical makeup, moisture, content, and general composition of a soil ▫ Physical and chemical weathering • Physical: Caused by heating and cooling, freezing and thawing, wind and water • Chemical: Reaction and interaction of water, oxygen, carbon dioxide, and other substances TOPOGRAPY • The surface features of a region including hills, valleys, rivers, lakes, and mountains • Causes particles to move up or down slopes and relocates the parent material • Soil is ever changing because of: ▫ Particle structures, sizes, types, amounts or organic and inorganic content, layers of soil, and pH values SOIL COMPOSITION • Minerals: The inorganic material in a soil ▫ Usually 64 elements • Organic matter is comprised of decayed or decaying plants or animals • Porous fraction of soil contains water and air ▫ Ideal ration is 50:50 SOIL PARTICLES • Particles are classed according to size • Coarse (largest particle size) ▫ Sand and gravel • Medium ▫ Silt • Fine (smallest particle size) ▫ Clay SOIL TEXTURE • Refers to the size of individual particles • Soil is a mixture of: ▫ Sand, silt, and clay • The percentage of each particle determines the soil’s ability to drain and hold water • Loam: Contains a percentage of sand, silt, clay, and organic matter ORGANIC MATTER SOIL TEXTURE TRIANGLE SOIL WATER • Leaching: Movement of water and nutrients away from plant roots • Capillary water: Held by the soil and available to plant through their roots • Gravitational water: Moves down and away from the surface by gravity, not used by plant roots • Hygroscopic water: Held so tightly by soil it is unavailable to plants SOIL pH • pH value: The acidity or alkalinity of a soil ▫ Plants have a preferred pH range ▫ pH scale = 0 – 14 Acidic: Below 7 Alkaline (basic): Above 7 Neutral: 7 • Soluble: Ability to dissolve • Microorganisms: Microscopic plant or animal life that decompose organic matter in soil or media PLANT MEDIUM • Requirements for a good plant medium: ▫ Moisture and nutrient retention ▫ Good porosity ▫ Provide support for the plant ▫ Shrinking and swelling ▫ Must be sterilized in greenhouses ▫ Has to be reproducible • Porosity: The air space (pores) between solid particles of soil or medium • Aeration: Movement of air through the soil SOIL MEDIA MATERIALS • Organic matter: Decomposing remains of plants and animals ▫ Loosens texture and holds water Compost: Dark soil of decomposed organic matter used as a fertilizer Peat Moss: Partially decomposed plant matter that has high water retention Sphagnum Moss: Dehydrated stems and leaves of acidic bog plants Pine Bark: ¼ inch or smaller pieces of bark which absorbs nutrients and releases them slowly NATURAL SOILS • Topsoil is the uppermost layer of soil and consists of: ▫ ▫ ▫ ▫ Air Water Minerals Organic Matter • The heaviest media material used is MASONRY OR PLASTER SAND which has sharp, coarse particle INORGANIC MEDIA MATERIALS • Inorganic matter: Media which contains no organic (plant or animal) particles ▫ Perlite: VOLCANIC rock crushed and heated to 1800 degrees Fahrenheit Improves aeration and water holding capacity ▫ Vermiculite: Mica compound heated to 2000 degrees Fahrenheit Improves moisture retention ▫ Wetting Agents: Chemicals which change the properties of water or other liquids SOILLESS MIXTURES • Artificial soils are media mixtures where soil has been replaced with other materials ▫ Developed because of the shortage of good horticultural-grade soils ▫ Agricultural and roadside soils have been treated and are harmful to plants Pesticides Construction materials Mineral salts SOILLESS MIXTURES • Extra consistency ▫ Maintained from batch to batch • Easy to use and cost less • Good drainage and aeration • Hydroponics: Growing method which uses a mineral-nutrient water solution instead of soil ▫ Growing solution can be easier than soil ▫ Can be expensive to set up and maintain