Slide 1 LHAP 105 Media Components Ppt developed by E.Kawahara Slide 2 Organic Matter Base Materials Slide 3 Field Soil **Field Soil is no longer used in container mixes.** Because of the potential for pathogens it needs to be Pasteurized. High Bulk Density is also an issue. In a container it limits aeration porosity. Field soil is not consistent. Slide 4 Pasteurization Pasteurization - eliminates organisms harmful to plants - no harm to beneficial soil organisms Soil should allow uniform penetration of steam fumigant See Chart – 60 degrees C for 30 minutes for most harmful organisms* Over steaming at too high temperature soil will be sterilized. Slide 5 Pasteurization Chart Weeds (most) 70°-80°C for 15 min. Insects and Mites 60°-71°C for 20 min. Bacteria (most) 60°C for 10 min. Fusarium 57°C for 30 min. Botrytis 55°C for 15 min. Nematodes 55°C for 15 min. Rhizoctonia 52°C for 30 min. Sclerotinia 50°C for 5 min. Pythium 46°C for 40 min. Slide 6 Pasteurization Methods Steam – fast, efficient, effective, economical Potted media – inject steam into bottom of a cart full of media, cool and fill pots Ground beds – If tiled for drainage, inject steam into tiles If no tiles, cover bed with tarp, inject steam directly under tarp Aerated steam Steam from a boiler is combined with air to create a 70oC mix that is pushed through the media. Slide 7 Soil pasteurizer https://www.mcgill.ca/plant/fr/media-gallery/detail/21/22 Slide 8 Peat Moss Acidic - pH of 3.5-5 Non-renewable-ish Low-ish Carbon Footprint high CEC, low salts, H2O holding capacity Adds O.M. with stability Difficult to re-wet. Slide 9 Coir Made from Coconut husk All the benefits of Peat (except better) PLUS: Easier to re-wet renewable Expands 5-9x (shipping) Better drainage - but holds water in micropores Slide 10 Materials that add Porosity Slide 11 Vermiculite Crushes easily Only one use Ties up Phosphates WILL NOT decompose! High Porosity, Low Db Sterile Dangerous to breathe Slide 12 Drainage and Aeration Low Bulk Density Inert Dangerous to breathe Floats Contains Fluoride Perlite Slide 13 Rice Hulls Sub for Perlite: Safer, Easily Renewable Good Porosity Stable within 1 year Sterile Slide 14 Sawdust/ Wood Products Used similarly to Vermiculite, Peat, or Coir… BUT Extreme variability and potential for toxins All wood products MUST be composted prior to use! Slide 15 Sand Stable and Inert Must be washed Heavy - increase Db good Drainage and Aeration when used alone Slide 16 Rockwool Low CEC Sterile Used for Propagation E.Wheale, 2015: Rockwool Media Slide 17 Additives Slide 18 Additives (Amendments) Wetting Agents - Can be gels or Floral Balls… Fritted and / or Chelated Trace Elements Superphosphate (root establishment) Osmocote (long term / nursery crops only) Slide 19 Lime Calcium Carbonate (or Calcitic lime) - CaCO3 Fairly quick impact For a pH change of 1 = 4,600 lbs / acre Sources: limestone, burned or hydrated lime Dolomitic Lime - CaCO3 + MgCO3 Slow Release Adds Magnesium Slide 20 Bio-Char Lightweight and Porous Carbon sink Variable (expensive to produce - GH grades are not priority production). Slide 21 Hydroponics Operations & Other Components... Often Hydroponics will still require some form of media for the roots. Rockwool bags are one option Growers also use Expanded Clay Pebbles (click here) Laterite in aquariums… for more info, click here Slide 22 Styrofoam and tire crumb are not considered useful in greenhouse media. Non-organic, Non-biodegradable, No Cation exchange… there are just too many better options