Where Does The Water Come From ?

1. Where Does The Water Come From ?

4. Examples of Variation in Groundwater Quality Well # 1 Well # 2 Well # 3 Soil Zone Sand and Gravel Aquifer Limestone or Granite Aquifer Sandstone Aquifer

6. Irrigation Water Alkalinity concentrations (ppm CaCO3) from Florida 25 20 15 10 5 0 Frequency % <40 40–80 80-20 120-160 160-200 200-240 240-280 280-320 320-360 360-400 >400

7. The Goal Is To Achieve A Stable Medium pH Over Time

8. Plant Growth Cycle Active Growth Establishment Mature

9. pH • pH affects the solubility of fertilizers, and the efficacy of pesticides and growth regulators. • the higher the water pH the less soluble these materials are

10. pH Drift 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 Alkaline Water pH “Optimum” Range NH4+ fertilizers Time

11. Alkalinity • A measure of water’s ability to neutralize acids – a buffering ability • Mostly carbonates and bicarbonates – associated with Ca and Mg (limestone) • May cause pH to rise in media over time, especially in small containers Note: Alkalinity “controls” pH Must know alkalinity to manage pH

12. Alkalinity • Expressed in ppm, mg/L, meq/L • Expressed as CaCO3 or HCO3- • Irrigation water should have an alkalinity of less than 100ppm; if higher than 150 ppm, acidification is needed

13. Alkalinity CaMg(CO3)2 Ca2+ + Mg2+ + 2CO32- Dolomitic limestone Hardness Hardness and Alkalinity Generally Go Hand-In-Hand but They Are NOT One and the Same You Can Use the Water Hardness to Estimate Its Alkalinity

14. Alkalinity Terms mg/liter or ppm CaCO3 of alkalinity mg/liter or ppm bicarbonate Milliequivalents alkalinity 1 2 3 4 5 50 100 150 200 250 60 122 183 244 305

15. Substrate Acidity 2CO32- + 2H + H2CO3 Alkalinity H2O + CO2 Both the alkalinity and the acidity are neutralized

16. The Effect of Water Alkalinity on Media pH and Acid Requirement Sample A Sample B pH = 9 pH = 7 Alk = 50 ppm Alk = 300 ppm Increases growing medium pH Little or no effect on the growing medium pH One drop of acid to get pH 6 Ten drops of acid to get pH 6

17. Action Steps To Correct High Alkalinity reverse osmosis 480 Alkalinity (ppm) bicarbonate acid injection 180 120 acid fertilizer and/or less lime none

18. SalinitySalinity is measured by Electro-conductivity • Total Dissolved Salts (TDS) – all salts present in the water (1 mMho/cm=640 ppm) • less than 0.75 mMho /cm for plugs • less than 1.0 mMho /cm for other greenhouse crops • less than 2.0 mMho /cm for other nursery crops

19. Testing The Soil Solution !

20. Pour Thru Method • Simple technique for measuring pH and EC • Charts for recording pH & EC • Guidelines for crops • Procedures to keep on track

21. 6 or 8-inch saucers are adequate for collecting the leachate

22. Distilled Water Volumes Pot Size ml oz 4 inch 5 inch 6 inch 6.5 inch 1 Qt 4 Qt 12 Qt 75 75 75 100 75 150 350 2.5 2.5 2.5 3.5 2.5 5.0 12.0

23. Flats: Use 50 ml Distilled Water

24. EC Comparisons 1:2 SME Indication PourThru 0 to 0.3 0.3 to 0.8 0.8 to 1.3 1.3 to 1.8 1.8 to 2.3 > 2.3 0 to 0.8 0.8 to 2.0 2.0 to 3.5 3.5 to 5.0 5.0 to 6.0 > 6.0 0 to 1.0 1.0 to 2.6 2.6 to 4.6 4.6 to 6.5 6.6 to 7.8 > 7.8 Very Low Low Normal High Very High Extreme

25. Initial EC

26. Crop pH Ranges

27. Geraniums (6” pinched) 6.0 to 6.6 1/28 6.6 to 6.8 5/01 5.8 to 6.0