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Soilless mixes

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Basics on soilless growing media. Physical, chemical characteristics and other attributes

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Soilless mixes

  1. 1. It all depends…. SOILLESS MIXESKevin Donnelly, CH.
  2. 2. GROWING MEDIA Air Water Structure Nutrient Reservoir
  3. 3. THE IDEAL MIX It all depends…. Fits your growing style Produces quality plants with limited management Consistent/Predictable Cost effective
  4. 4. PHYSICAL PROPERTIES
  5. 5. MACRO VS. MICROPORES 30% Air 75% Water 45% Water 25% Solids 25% Solids
  6. 6. CAPILLARY ACTION IN MIX Important when sub irrigating containers Pores act as a straw and
  7. 7. ZONE OF SATURATION Amount mix will hold at the bottom
  8. 8. CONTAINER SIZE Size and Shape of container can effect water air water relationships  Look at the force of gravity 45% Air 25% Air 10% Air
  9. 9. BULK DENSITY/ COMPACTION Depending on how it is filled can impact air water relationships Compact vs. lightly filed
  10. 10. SHRINK Settling after watering Component breakdown Out the bottom? Shrink from blending
  11. 11. WHY IT MATTERS Overwatering or under watering causes issues Pick up method of checking watering status  If I change the weight of your mix, you will mess up  Surface may dry up but not underneath  Knock out pots to check
  12. 12. WETTING AGENT Aids in wetting up mix  Peat is hydrophobic Helps with even watering,  Not channeling down the sides of the pot A good idea for postharvest quality
  13. 13. CHEMICAL PROPERTIES
  14. 14. PH Will effect nutrient availability Fluctuates over the course of the crop The plant causes pH changes Alkalinity of your water is important  May need to do acid injections Buffer capacity of your components Lime and Iron Sulfate
  15. 15. PH
  16. 16. EC AKA soluble salts Measure of salt content in solution Can be from good salts or bad Many use EC as indication of fertility Listed in dS/m or ppm (dS/m X 670) Dilution method matters!!
  17. 17. NUTRIENTS Minerals/non coated  dolomite lime  Iron Sulfate Controlled Release Fertilizers (CRF or SRF)  Encapsulated NPK+ Organic Fertilizers  Often have low analysis and low availability (predictable)
  18. 18. OTHER MEASURMENTS Organic Matter CEC C:N Weed Seed presence Wettability Moisture content
  19. 19. TESTING What do you test for How Often How do you test  Interal testing  External lab What do you do with that information
  20. 20. SAMPLING How you sample may add bias to the test Area of pot  Top 1/3rd  Middle 1/3rd  Bottom 1/3rd Random sample or targeted sample
  21. 21. TESTING FOR PHYSICAL PROPERTIES Air Porosity  Field Method  NCSU Porometer Sieve analysis
  22. 22. TESTING CHEMICAL In house  EC  pH External Lab  Nutrients  CEC  Etc.
  23. 23. EC Method maters  1:1  2:1  SME  Pour Thru Many use it for managing fert  If EC reading falls below X, then fertigate
  24. 24. PH TESTING Moving Target Can be adjusted 7 6.5 6 5.5 5 4.5 4 1 2 3 4 5 6 7 8 9
  25. 25. BIG POINT FOR ANY TESTING Don’t make major changes right after testing starts to correct issues that may be normal Need historical values to see what is your norm Plants don’t read test reports
  26. 26. BIOLOGICAL Mycorrhizae Benificial bacteria/fungi These can be incorporated into mix  As well as some pesticides
  27. 27. Its all about logisticsCOMPONENTS
  28. 28. AGGREGATES Perlite  Others Vermiculite  Lava  Glass Sand  Polystyrene Calcined clay  Rockwool  Oildri  LWA
  29. 29. ORGANIC COMPONENTS Peat  “Composts”  Landscape compost  Sphagnum  Manure compost  Reed Sedge  Biosolids Pine  Worm Casting Rice  Mushroom “Compost” Coir  Spent Mushroom Substrate
  30. 30. NEW PRODUCTS Why we need them  Look for local  Price  Cheap  Availability  Effective  Quality  Sustainability These are not replacements
  31. 31. NEW FRONTIERS Whole Tree Substrate Corn Cobs Miscanthus Biochar
  32. 32. MANAGING RAW COMPONENTS These are natural products They vary They change over time How you manage them maters

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