Managing Water Quality in Growing Media

1. Managing Water Quality in Growing Media David Wm. Reed Department of Horticultural Sciences Texas A&M University

2. Factors That Impact Water Quality in Growing Media

3. Factors That Impact Water Quality in Growing Media

4. Factors That Impact Water Quality in Growing Media

5. Factors That Impact Water Quality in Growing Media

6. Factors That Impact Water Quality in Growing Media

7. Factors That Impact Water Quality in Growing Media

8. Factors That Impact Water Quality in Growing Media

9. Factors That Impact Water Quality in Growing Media

10. Factors That Impact Water Quality in Growing Media

11. Factors That Impact Water Quality in Growing Media

12. Factors That Impact Water Quality in Growing Media Irrigation Water Quality

13. Factors That Impact Water Quality in Growing Media

14. Irrigation Water Quality Chemical Properties pH alkalinity EC SAR Individual Soluble Salts Water Treatment Methods

15. Growing Medium EC and pH (from Lang 1996)

16. Irrigation Water Alkalinity Limits Minimum Maximum ppm meq/l ppm meq/l Plugs and/or seedlings38 0.75 66 1.3 Small pots/shallow flats 38 0.75 86 1.7 4" to 5" pots/deep flats 38 0.75 106 2.1 6” pots/long term crops 63 1.25 131 2.6 (from Bailey 1996)

17. Irrigation Water Critical Limits (from Biernbaum 1994)

18. Plant Nutrient Requirements Supplied by Irrigation Water

19. Sulfur Supplied by Irrigation Water 20-30 ppm supplies most plant’s requirement (from Reddy 1996)

20. Irrigation Water Quality Water Treatment Methods

21. Water Purification Methods (from Reed 1996)

22. Reverse Osmosis Unit

23. Reverse Osmosis Water Purification To Decrease Salts Pretreatments: 1) Polymer injection to coagulate due to high SDI 2) Depth Filter to remove coagulated particles 3) Charcoal Filter to remove municipal chlorine 4) Ion Exchange to remove residual polymer Purification System: Reverse Osmosis using polyamide membranes (pH resistant, chlorine sensitive) Production Capacity Purified Water 5,760 gallons per day Blended Water (40/60) 14,400 gallons per day Blend to EC of 0.75 dS/m (approx. 500 ppm) (from Reed 1996)

24. Reverse Osmosis Water Purification To Decrease Salts Costs Lease and Service $900 per month Water (1.09/1,000) $700 per month Electricity $200 per month Total $1800 per month Purified Water Cost1 cent per gallon Blended Water Costs0.4 cents per gallon Production Space Irrigated 80,000 to 135,000 square foot of 6-inch production space (at 12-20 oz/6”pot/day at 0.9 sq. ft. space/6”pot) Purified Water Used For Salt sensitive foliage plants and mist propagation (from Reed 1996)

25. Acid Injection80% Neutralization to Approx. pH 5.8 Fluid ounce of acid ppm per 1,000 of water, per oz. per for each meq 1,000 gal Acid of alkalinity water Nitric (67%) 6.78 1.64 N Phosphoric (75%) 8.30 2.88 P Sulfuric (35%) 11.00 1.14 S (from Bailey 1996)

26. Fertilizer Program Soluble Liquid Feed Granular Incorporation Controlled Release Incorporation

27. Factors That Impact Water Quality in Growing Media

28. EC of Soluble Fertilizers & Water Quality (from Peterson 1996)

29. Fertility & Salt Stratification in the Root Zone Subirrigation – New Guinea Impatiens ‘Barbados’ (from Kent & Reed 1996)

30. Irrigation Method Top-Watering vs. Subirrigation Vertical Stratification of Salts Evaporation from Surface Leaching Fraction

31. Factors That Impact Water Quality in Growing Media

32. Vertical Stratification of Soluble Salts

33. Salt Stratification in the Root Zone with Different Irrigation Methods (from Molitor, 1990, Warncke & Krauskopf 1983)

34. Evaporation from Surface Causes Vertical Stratification of Salts

35. Effect of Evaporation on Salt Stratification Poinsettia ‘Gutbier V-14 Glory’ (from Argo and Biernbaum 1995 Warncke & Krauskopf 1983)

36. Effect of Evaporation on Salt Stratification Poinsettia ‘Gutbier V-14 Glory’ (from Argo and Biernbaum 1995 Warncke & Krauskopf 1983)

37. Vertical Stratification of Soluble Salts and Root Distribution

38. Salt Stratification & Root Distribution Spathiphyllum in subirrigation (from Kent & Reed, unpubl; Warncke & Krauskopf 1983)

39. Track EC to Monitor Soluble Salt Accumulation Over Fertilization Minimum Fertility Level Caution: DO NOT sample the top layer

40. Graphical Tracking: EC Crop: ______________________

41. Leaching Fraction and Soluble Salt Accumulation

42. Leaching in Top-Watering Vs. Subirrigation

43. Leaching Fraction in Top-Watering Low LF LF ~ 0.3-0.4 High LF LF @ ECw / (5(ECe(desired)-ECw))

44. Effect of Leaching Fraction on Medium EC Poinsettia ‘V-14 Glory’ 0 LF 0.15 LF 0.35 LF 0.55 LF (from Yelanich and Biernbaum 1993, Warncke & Krauskopf 1983)

45. Top Layer Salts and Wilting Upon IrrigationEspecially Critical in Subirrigation (from Todd & Reed 1998)

46. Leaching & Salt Removal From MediaNew Guinea Impatiens ‘Blazon’ in Subirrigation (from Todd & Reed 1998)

47. Determination of Soluble Salt Toxicity Limits “Shoot Gun” Approach

48. Plant Response to 24 Texas Water Sources 1.1 0.5 0.2 0.9 0.3 0.7 0.3 1.0 0.8 0.8 0.1 0.5 0.1 0.5 0.2 0.4 1.2 (from Kent & Reed unpubl)

49. Growth Versus EC with 24 Water Sources Vinca ‘Apricot Delight’ Grown in Subirrigation (from Kent & Reed unpubl)

50. Growth Versus EC with 24 Water Sources Vinca ‘Apricot Delight’ Grown in Subirrigation (from Kent & Reed unpubl)