Managing Water Quality in Growing Media

1
Managing Water Quality in Growing Media

• David Wm. Reed
• Department of Horticultural Sciences
• Texas AM 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 seedlings 38 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 plants 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 Cost 1 cent per gallon
• Blended Water Costs 0.4 cents per gallon
• Production Space Irrigated
• 80,000 to 135,000 square foot of 6-inch
  production space
• (at 12-20 oz/6pot/day at 0.9 sq. ft.
  space/6pot)
• 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 Poins
ettia Gutbier V-14 Glory
(from Argo and Biernbaum 1995 Warncke Krauskopf
1983)
36
Effect of Evaporation on Salt Stratification Poins
ettia 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 Spathiphy
llum 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
LF 0.3-0.4
Low LF
High LF
LF _at_ 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
0.5
0.1
0.1
0.2
0.5
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)
51
Growth Versus EC with 24 Water Sources Vinca
Apricot Delight Grown in Subirrigation
(from Kent Reed unpubl)
52
Growth Versus Na Cl with 24 Water Sources Vinca
Apricot Delight Grown in Subirrigation
(from Kent Reed unpubl)
53

• Determination of
• Soluble Salt Toxicity Limits
• Studies on Individual Salts
• (cation anion combinations)

54
Toxicity Limits to Sodium Bicarbonate
0 mM
2.5 mM
5 mM
Rose
7.5 mM
10 mM
Chrysanthemum
0 mM
2.5 mM
5 mM
7.5 mM
10 mM
(from Valdez, PhD)
55
Predicted NaHCO3 Toxicity Limit as a Function of
Chlorosis
(from Valdez, PhD)
56

• Determination of
• Soluble Salt Toxicity Limits
• Studies on Individual Salts
• (cation anion combinations)
• Problem With This Approach
• Do not know if the effect is due to the cation or
  the anion

57
Determination of Soluble Salt Toxicity
Limits Separation of Anion and Cation Effects
Using Mixture Experiments
58
Pure blends
Mixture Experiment Design
X 100
Tertiary blends
Centroid
2/31/61/6
Binary blends
½½0
1/31/31/3
1/62/31/6
1/61/62/3
Z 001
Y 010
0½½
59
Mixture-Amount Experiments to Separate the Na
and HCO3- Effect in Sodium Bicarbonate
Na tox./K def.-19
Shoot Dry Mass (g)
0 mM HCO3
HCO3- effect-15
7.5 mM HCO3
(from Valdez, PhD)
60

Binary Mixture Experiments to Separate the Na
and HCO3- Effect in Sodium Bicarbonate
2.5 mM total binary mixture
0 HCO3-
Na-19
Shoot Dry Mass (g)
HCO3--19
2.5 HCO3-
Na
K
Proportion of K and Na
(from Valdez, PhD)
61
Mixture-Amount Experiments To Separate Chloride,
Bicarbonate and Sulfate Effects
(from Kent Reed unpubl)
62
Separation of Chloride, Bicarbonate and Sulfate
Effects with Mixture-Amount Experiments
Vinca Pacifica Red in Subirrigation
HCO3
HCO3
HCO3
Cation Na
Cation Na
Cation Na
SO4
SO4
SO4
Cl
Cl
Cl
45 meq/l
30 meq/l
60 meq/l
(from Kent Reed unpubl)
63
Mixture-Amount Experiments To Separate Chloride,
Bicarbonate and Sulfate Effects
Vinca Pacifica Red in Subirrigation
HCO3
HCO3
HCO3
Cation Na
Cation Na
Cation Na
SO4
SO4
SO4
Cl
Cl
Cl
45 meq/l (2,300 to 3,400 ppm)
30 meq/l (1,700 to 2,500 ppm)
60 meq/l (2,800 to 4,400 ppm)
(from Kent Reed unpubl)
64
Thanks
65
EC of Soluble Fertilizers Water Quality
66
Separation of Sodium and Bicarbonate Effect Using
Mixture Experiments
g shoot mass
Na tox./K def.-19
HCO3- effect-15
(from Valdez, Ph.D. dissertation)
67
Leaching Salt Removal From MediaNew Guinea
Impatiens Illusion in Subirrigation
(from Todd Reed 1998)