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SOIL

SOIL. SOIL. Physical elements {TILTH} – e.g. sand, silt, clay, organic material and aggregates (see SOIL {1}) Living elements (other than plants) – e.g. nematodes , earthworms , fungi, protozoa, bacteria, insects, spiders, mites… ( see SOIL {2}) Chemical elements

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SOIL

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  1. SOIL

  2. SOIL • Physical elements {TILTH} – e.g. sand, silt, clay, organic material and aggregates (see SOIL {1}) • Living elements (other than plants) – e.g. nematodes, earthworms, fungi, protozoa, bacteria, insects, spiders, mites… (see SOIL {2}) • Chemical elements –pH and its effect on nutrients (primary, secondary and micro- nutrients); water; oxygen

  3. pH A controversial topic!!??

  4. pH – a controversial topic

  5. pH – a controversial topic Author has gardened in Oregon, Canada, California and now lives in Australia – the article was adapted from a book published by MOTHER EARTH NEWS titled, “Book for Wiser Living”.

  6. Research based information • The previous two slides were not from a source that bases its findings on research. • When looking for accurate information online, be sure the source ends with .eduor .gov.

  7. Significance of pH • Soil pH is one of the most important soil measurements.  It plays a huge role in the availability of nutrients to plant roots, nutrient run-off, leaching and microbial efficiency

  8. Root development of tomato plants in self-watering containers pH 6.5 pH 3.8 & 5 Low pH (5 and below) and low Ca result in damage to root membranes. http://hubcap.clemson.edu

  9. Root development in self-watering containers pH 3.8 in 30 gallon tub (lack of healthy white roots) pH 6.2 5-gallon (healthy, white roots)

  10. What is pH? • p= proportion / H = of H+ ions • Relative concentration of H+ in water • H20 H+ + OH- • H+ and OH- must always be equal in a neutral solution • Water has properties of both a weak acid and a weak base.

  11. Significance of pH • Chemical controls (insecticides, fungicides, miticides) • Nutrient availability • Root system development • Microbial activity

  12. Significance of pH • Chemical controls (insecticides, fungicides and miticides) • Ideal pH range between 5.5 to 6 • Acceptable range is 4 – 7

  13. Insecticides and basic pH of water • The effectiveness of some classes of insecticides is greatly reduced when the pH of the water used for dilution is at or over a pH of 8. • In these instances, a high temperature also reduces the effectiveness. (Alkaline hydrolysis)

  14. Insecticides and basic pH of water • Most susceptible are: ORGANOPHOSPHATES (malathion) -(and DIMETHOATE, a mitecide), • CARBAMATE (Sevin), and some PYRETHROIDS. • Fungicides are not sensitive to pH. ≈pH precautions not usually on the label≈

  15. Biologicals and pH • A pH over 8 will reduce the effectiveness of BT (Bacillus thuringiensis) • Never mix COPPER SULFATE, COPPER OXIDE or BORDEAUX MIXTURE with acidic water…they may produce a phytotoxic effect.

  16. Insecticides/Fungicides and pH

  17. Treat ‘em all alike • Rather than try to memorize which insecticides and miticides are sensitive to pH, threat them all with the same precautions until you are certain that they will be unaffected. • Using the wrong pH can render the chemical ineffective.

  18. pH of water to dilute insecticide • pH range of 3.5 – 6.0 • Spray • Short term storage of 12 to 24 hours • pH range of 6.1 – 7.0 • Spray • Do not leave in leave in sprayer over 2 hours • pH above 7 or below 3 • Do not use to mix insecticide

  19. St. Tammany Water pH

  20. Municipal water supplies Why are they all alkaline (above a pH of 7) (Because an acidic pH will dissolve copper pipes over time)

  21. Practical significance of pH

  22. http://plantsinaction.science.uq.edu.au Primary nutrients • N+/- • P+ • K+ • S- • Ca+ • Mg+ • Fe+ • Mn+ • Cu+ • Zn+ • B+ • Mo- • Al+ Secondary nutrients Micronutrients {Ni+ and Cl- are sometimes included}

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