Copy of Media Intro

Slide 1 LHAP 105Media Introduction Developed by LHAP/Horticulture Olds College - ‹#› Slide 2 Media defined: A component or combination of components designed to give the optimum ratio of AIR, WATER, and MINERALS to a given crop and provide sufficient SUPPORT. (4 Basic Functions) Slide 3 Media Components Sphagnum peat Coir fibre Mineral soils Vermiculite, Perlite Rice Hulls, Sand Pine bark Rockwool What Are They?! Slide 4 Properties of a Container Media A. Physical properties Chemical properties C. Biological properties D. Other desirable characteristics Slide 5 Physical properties – Media must provide: 1. Support Keeps plants upright Anchors roots Slide 6 Bulk Density (Db) Defined = the mass (weight) of dry solids in relation to the bulk (volume) of the media. Db= oven dried weight of media (g) volume of soil (in cc or ml) Slide 7 Bulk Density applied For ease of handling, a light Db is desirable (optimum pore spaces and low pot weight)... but it MUST still support the plant. Slide 8 A. Physical properties 2. Total Porosity Defined: Percentage of media composed of pore spaces *Greenhouse media optimum: 75-85% pore spaces* Slide 9 A. Physical properties 3. Aeration Porosity: MACROPORES Water drains quickly through media with large pores 15-20% Pa= Large Containers (nursery) 20-25% Pa = For Rapid Growth (GH) Slide 10 Physical properties 4. Capillary Porosity MICROPORES Slide 11 Symptoms of poor aeration and prolonged water logging of media Wilting Roots with brown tips Lack of root hairs Sour smell Rotten egg odor Stunted growth Chlorosis in older leaves Necrotic margins Roots forming on stems at media surface Slide 12 Physical properties 5. Stable organic matter (note the difference between STABILITY and SUPPORT) Provides aeration, drainage and water holding capacity Slide 13 Chemical Properties Slide 14 B. Chemical properties Media components can affect mineral content and availability: Slide 15 Chemical properties Cation Exchange Capacity (C.E.C) The sum of the exchangeable cations that media can retain per unit weight Slide 16 B. Chemical properties Hatched areas indicate ranges of Cation Exchange Capacity (meq/L) for media components Slide 17 B. Chemical properties 2. 2. Acceptable pH Determination of Acidity or Alkalinity! GH mixes ideal pH = 5.5-6.5 Slide 18 Availability of Nutrients in relation to media pH https://extension.uga.edu Slide 19 Chemical properties 3. Low soluble salts/initial low fertility Dissolved mineral salts found in media Can be a source of mineral supply - Can also be toxic Slide 20 B. Chemical properties 4. Buffering Capacity described as the media’s ability to resist change in pH *Components with high CEC also have high buffering capacity* Slide 21 BIOLOGICAL PROPERTIES Photo source: Filter Forge Slide 22 C. Biological Properties Two considerations: Presence or absence of Harmful Pathogens 2. Presence or absence of Beneficial Microorganisms Slide 23 Biological Properties 1. Pest free Components are considered sterile from the bag ** Mineral Soil MUST be PASTEURISED prior to use ** Slide 24 Biological Properties 2. Beneficial microorganisms Compost brings biological life to a mix Mycorrhizae… (Myke) Slide 25 D. Other desirable characteristics of media 1. Biologically, physically, chemically stable 2. Standardized and uniform from batch to batch 3. Media components should be: Economical Readily available Easily mixed Light in weight