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

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Managing Water Quality in Growing Media


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managing water quality in growing media

Managing Water Quality in Growing Media

David Wm. Reed

Department of Horticultural Sciences

Texas A&M University

irrigation water quality

Irrigation Water Quality

Chemical Properties

pH

alkalinity

EC

SAR

Individual Soluble Salts

Water Treatment Methods

slide15

Growing Medium EC and pH

(from Lang 1996)

irrigation water alkalinity limits

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)

sulfur supplied by irrigation water
Sulfur Supplied by Irrigation Water

20-30 ppm supplies most plant’s requirement

(from Reddy 1996)

irrigation water quality1

Irrigation Water Quality

Water Treatment Methods

reverse osmosis water purification to decrease salts

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)

reverse osmosis water purification to decrease salts1

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)

acid injection 80 neutralization to approx ph 5 8

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)

fertilizer program

Fertilizer Program

Soluble Liquid Feed

Granular Incorporation

Controlled Release Incorporation

slide29

Fertility & Salt Stratification in the Root Zone

Subirrigation – New Guinea Impatiens ‘Barbados’

(from Kent & Reed 1996)

irrigation method

Irrigation Method

Top-Watering vs. Subirrigation

Vertical Stratification of Salts

Evaporation from Surface

Leaching Fraction

slide33

Salt Stratification in the Root Zone with Different Irrigation Methods

(from Molitor, 1990, Warncke & Krauskopf 1983)

evaporation from surface causes vertical stratification of salts
Evaporation from Surface

Causes Vertical Stratification of Salts

slide35

Effect of Evaporation on Salt Stratification

Poinsettia ‘Gutbier V-14 Glory’

(from Argo and Biernbaum 1995

Warncke & Krauskopf 1983)

slide36

Effect of Evaporation on Salt Stratification

Poinsettia ‘Gutbier V-14 Glory’

(from Argo and Biernbaum 1995

Warncke & Krauskopf 1983)

slide38

Salt Stratification & Root Distribution

Spathiphyllum in subirrigation

(from Kent & Reed, unpubl;

Warncke & Krauskopf 1983)

slide39
Track EC to Monitor

Soluble Salt Accumulation

Over Fertilization

Minimum Fertility Level

Caution: DO NOT sample the top layer

graphical tracking ec
Graphical Tracking: EC

Crop: ______________________

leaching fraction and soluble salt accumulation
Leaching Fraction

and

Soluble Salt Accumulation

leaching fraction in top watering

Leaching Fraction in Top-Watering

Low LF

LF ~ 0.3-0.4

High LF

LF @ ECw / (5(ECe(desired)-ECw))

slide44

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)

top layer salts and wilting upon irrigation especially critical in subirrigation

Top Layer Salts and Wilting Upon IrrigationEspecially Critical in Subirrigation

(from Todd & Reed 1998)

leaching salt removal from media new guinea impatiens blazon in subirrigation

Leaching & Salt Removal From MediaNew Guinea Impatiens ‘Blazon’ in Subirrigation

(from Todd & Reed 1998)

determination of soluble salt toxicity limits shoot gun approach
Determination of

Soluble Salt Toxicity Limits

“Shoot Gun” Approach

slide48

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)

slide49

Growth Versus EC with 24 Water Sources

Vinca ‘Apricot Delight’ Grown in Subirrigation

(from Kent & Reed unpubl)

slide50

Growth Versus EC with 24 Water Sources

Vinca ‘Apricot Delight’ Grown in Subirrigation

(from Kent & Reed unpubl)

slide51

Growth Versus EC with 24 Water Sources

Vinca ‘Apricot Delight’ Grown in Subirrigation

(from Kent & Reed unpubl)

slide52

Growth Versus Na + Cl with 24 Water Sources

Vinca ‘Apricot Delight’ Grown in Subirrigation

(from Kent & Reed unpubl)

determination of soluble salt toxicity limits studies on individual salts cation anion combinations
Determination of

Soluble Salt Toxicity Limits

Studies on Individual Salts

(cation + anion combinations)

slide54

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)

slide55

Predicted NaHCO3 Toxicity Limit as a

Function of Chlorosis

(from Valdez, PhD)

slide56

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

slide57

Determination of

Soluble Salt Toxicity Limits

Separation of Anion and Cation Effects Using Mixture Experiments

slide58

½:0:½

Pure blends

Mixture Experiment

Design

X

1:0:0

Tertiary blends

Centroid

2/3:1/6:1/6

Binary blends

½:½:0

1/3:1/3:1/3

1/6:2/3:1/6

1/6:1/6:2/3

Z

0:0:1

Y

0:1:0

0:½:½

mixture amount experiments to separate the na and hco 3 effect in sodium bicarbonate
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)

slide60

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)

slide61

Mixture-Amount Experiments To Separate

Chloride, Bicarbonate and Sulfate Effects

(from Kent & Reed unpubl)

slide62

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)

slide63

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)

slide66

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)

leaching salt removal from media new guinea impatiens illusion in subirrigation

Leaching & Salt Removal From MediaNew Guinea Impatiens ‘Illusion’ in Subirrigation

(from Todd & Reed 1998)