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Where Does The Water Come From ?. Examples of Variation in Groundwater Quality. Well # 1. Well # 2. Well # 3. Soil Zone. Sand and Gravel Aquifer. Limestone or Granite Aquifer. Sandstone Aquifer. Irrigation Water Alkalinity concentrations (ppm CaCO 3 ) from Florida. 25 20 15

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Where Does The Water Come From ?

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Where does the water come from

Where Does The Water Come From ?


Examples of variation in groundwater quality

Examples of Variation in Groundwater Quality

Well # 1

Well # 2

Well # 3

Soil Zone

Sand and Gravel Aquifer

Limestone or Granite Aquifer

Sandstone Aquifer


Where does the water come from

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


The goal is to achieve a stable medium ph over time

The Goal Is To Achieve A Stable Medium pH Over Time


Plant growth cycle

Plant Growth Cycle

Active Growth

Establishment

Mature


Where does the water come from

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


Ph drift

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


Alkalinity

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


Alkalinity1

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


Where does the water come from

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


Where does the water come from

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


Where does the water come from

Substrate Acidity

2CO32- + 2H +

H2CO3

Alkalinity

H2O + CO2

Both the alkalinity and the acidity are neutralized


The effect of water alkalinity on media ph and acid requirement

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


Action steps to correct high alkalinity

Action Steps To Correct High Alkalinity

reverse osmosis

480

Alkalinity (ppm) bicarbonate

acid injection

180

120

acid fertilizer and/or

less lime

none


Salinity salinity is measured by electro conductivity

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


Where does the water come from

Testing The Soil Solution !


Pour thru method

Pour Thru Method

  • Simple technique for measuring pH and EC

  • Charts for recording pH & EC

  • Guidelines for crops

  • Procedures to keep on track


Where does the water come from

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


Distilled water volumes

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


Where does the water come from

Flats: Use 50 ml Distilled Water


Ec comparisons

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


Initial ec

Initial EC


Crop ph ranges

Crop pH Ranges


Where does the water come from

Geraniums (6” pinched)

6.0 to 6.6

1/28

6.6 to 6.8

5/01

5.8 to 6.0


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