The purpose of this supplement is to provide you with explanations and guidelines that will allow you to understand and use the results of your water analysis.  The water analysis report will be discussed in three separate sections.

SECTION I: This section reports the concentration of the major ions in water.  The major cations (ions with a plus charge) are Calcium, Magnesium, Sodium and Potassium.  Major anions (ions with a negative charge) are Sulfate, Chloride, Carbonate and Bicarbonate.

Concentrations of the major cations and anions are reported both as parts per million (ppm) and as milliequivalents per liter (meq).  Milliequivalents may not be a familiar term.  It is simply a method of expressing the concentration of these ions on the basis of their reactivity with other ions.

Step 1 - Calcium, Magnesium, and Sulfate: These essential plant macronutrients are not normally supplied in complete Fertilizer.  If your water contains low levels of Calcium, Magnesium, or Sulfate, you may need to include them in your fertility program.

Step 2 - Potassium and Phosphate: These essential plant macronutrients normally occur in very low concentrations in water.  If your water contains more than a few ppm of these elements there is a possibility that your water may contain fertilizer, detergent, or other contaminants.

Step 3 - Sodium and Chloride: If your water contains high levels of Chloride it will usually have high levels of Sodium; however, the reverse is not true.  Many waters can contain significant amounts of Sodium without containing high levels of Chloride.

Chloride levels less than 140 ppm are safe for most plants.  Chloride sensitive plants may experience tip or marginal leaf burn at concentrations above 20 ppm.  High levels of Sodium in your water may cause plant toxicities or induce deficiencies of other elements.  If Sodium predominates in the soil solution Calcium and Magnesium may be leached out of the media.  Excess Sodium can degrade the physical structure of the growing media resulting in reduced drainage and poor root development.  The Sodium Adsorption Ratio (SAR) is a calculated value that indicated the potential for Sodium related problems in water.

If the SAR is less than 4, Sodium should not be a problem.

STEP 4 - Carbonate and Bicarbonate: The Carbonate concentration is one of the most important factors influencing how water effects growing media pH.  This is the sum of the Carbonate and Bicarbonate values listed on the analysis.  Ideally, the total Carbonates should be less than 2 meq.  (Note: When determining the Carbonate and Bicarbonate values use meq not ppm.)

Excess of total Carbonates can cause media pH levels to rise to unacceptable levels.  If you grow bedding plants plugs and have yellowing problems (especially with petunias) or grow foliage plants and experience interveinal chlorosis of the new growth, you should evaluate your water=s total Carbonate level.  These problems may be symptoms of iron or trace element deficiencies caused by high media pH.

The total Carbonates in your water can be reduced by lowering the pH of your water through acid injection.  Refer to Table 1 of this supplement for additional information on acid injections.

WARNING: Use acids very carefully.  Safety precautions such as proper eye and skin protection should be used when handling acids.  Add acid to water - never water to acid.  Acids also supply plant nutrients and modification of your fertility program may be necessary.  Analyze your water after acid injection and confirm that you have achieved the desired results.

SECTION II: This section reports the Nitrate, Ammonium, and Fluoride levels in your water.  Also included are soluble salts (EC), pH, and water hardness.

Step 1 - Nitrate and Ammonium: Nitrate and Ammonium provide Nitrogen to the plant and will not cause plant damage if present at moderately low levels.  Water with Nitrate levels greater than 10 ppm is unsafe for drinking purposes.  Ammonium levels are normally very low in water.

Step 2 - pH: Water pH values will vary source to source and region to region.  The significance of high water pH will depend upon the total Carbonate concentration in the water.  If water pH is high and total Carbonates are high, you may experience high media pH values.  If water pH is high and Carbonates are low, media pH values can generally be controlled with your fertilizer.  The use of acidic fertilizers with low Carbonate water may result in low media pH values.

Step 3 - Water hardness, soluble salts, and Fluoride: Water hardness is an indication of the Calcium and Magnesium in your water.  Moderately hard water, 100-150 mg CaCO₃/liter, is desirable for plant growth.  If your water is very soft, less than 50 mg CaCO₃/liter you may need to provide supplemental Calcium or Magnesium to your plants.

Soluble salts (EC) are discussed in the general interpretative guideline provided with the water analysis report.

Fluoride levels are an indicator of the suitibility of your water for the irrigation of Fluoride sensitive crops.  Fluoride levels above 0.75 ppm may cause tip burn on sensitive foliage or bulb crops.

SECTION III: This section reports the concentration of 18 additional elements in your water.  With the exception of Silicon, the concentration of these elements should be very low.

Boron toxicities (especially with Poinsettias) are a common problem experienced by many growers.  Consider the additive concentration of Boron provided in your media + fertilizer + water, rather than a single component alone.

TABLE 1: Acid injection into irrigation water.