| Material Information
||Water quality tests for low volume irrigation
||Lake Alfred AREC reseach report
||2 p. : ; 28 cm.
||Ford, Harry W., 1922-
Agricultural Research and Education Center (Lake Alfred, Fla.)
||University of Florida, IFAS, Agricultural Research and Education Center
||Place of Publication:
||Lake Alfred FL
||Irrigation -- Florida ( lcsh )
Water -- Purification -- Florida ( lcsh )
Water quality -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )
||Statement of Responsibility:
||Harry W. Ford.
||"5/30/79 (Revised 11/15/80)-HWF-100."
| Record Information
||University of Florida
||All rights reserved by the source institution and holding location.
||oclc - 76883439
Lake Alfred AREC Research Report-CS79-6
5/30/79 (Revised 11/15/80)-HHF-100
WATER QUALITY TESTS FOR LOW VOLUME IRRIGATION
Harry W. Ford
University of Florida, IFAS
Agricultural Research and Education Center
Lake Alfred, Florida 33850
Measurements for water quality can be restricted to those factors most likely to cause
clogging problems in a particular area.
Surface water should be tested for completed iron, pH, estimated chlorine, suspended
solids, and soluble salts (if you are in a salty area).
Shallow open wells have serious water quality problems. -Tests should include iron,
hydrogen sulfide, pH, estimated chlorine, and suspended solids. If the pH is above 7.5,
check for lime carbonates.
Deep wells may require tests for iron, hydrogen sulfide, pH, estimated chlorine,
possibly suspended solids, soluble salts, and lime carbonates (if the well does not
contain sulfides and the pH is above 7.5).
Practically all of the tests can be performed by the grower without sending the water
samples to a laboratory. Samples sent to a laboratory must be preserved to prevent iron
precipitation and loss of sulfides. Check with the laboratory for the methods they use
for preserving samples.
Iron. The most accurate measurements are obtained at the site. Purchase an iron test
kit containing a color comparison wheel that reads from 0 to 5 ppm (mg/L). The cost is
about 7,25 and your County Extension Aoent or irrigation dealer center can tell you where
to purchase a kit. NEVER LET THE CHEMICALS OF ANY TEST KIT LAY AROUND IN A HOT CAR OR
TRUCK. Store the pillows or tablets in a refrigerator. The iron concentration of surface
waters and wells will fluctuate during the season. Read for iron at intervals and adjust
the chlorine treatment. SEE: Lake Alfred AREC Res. Rept. CS79-3 "A key for determining
the use of sodium hypochlorite to inhibit iron and slime clogging of low pressure
irrigation systems in Florida."
Hydrogen sulfide. Sulfides can be detected by noting a white slime at outlets, by the
odor in the air, by taking a.pint sample and adding 10 drops of muriatic (hydrochloric)
acid for laboratory analysis, and by using test kits for on-site measurements. The
cheapest semi-quantitative test kit involves the use of a piece of filter paper
impregnated with lead acetate. An Alka-seltzer or other brand type fizz tablet is placed
in a small sample of water and the opening covered with the filter paper. The bubbling of
the solution drives the gas through the filter paper which turns brown to black from lead
sulfide. The test is sufficient to consider chlorine treatments for sulfides. (SEE: Lake
Alfred AREC Res. Rept. CS75-4 (Revised 11/15/80) "Slimes of sulfur in low volume
pH. This is a standard procedure using.a pH meter that is often available. If the
water is taken to the County Agent's office or laboratory, be sure the time interval from
sampling to reading is not over 3 hours because the pH may change by as much as one full
Suspended solids and particulate material. Quantitative tests for suspended solids
are complicated but one can get an indication by using a clean glass jar and taking a
water sample. Place the sample in a dark room for 12 hours. Shine a spot type light beam
through the jar. Particulate material will be visible on the bottom. Suspended solids
will show up in a light beam. Consider suspended solids a potential problem if the light
beam is a brilliant white and very opaque.
The light beam test can also be used when fertilizers are injected into lo,; pressure
irrigation systems. Collect some of the diluted solution from the irrigation system and
perform the test listed above and compare with a water sample that did not receive
fertilizer injection. The test will tell you if fertilizers can contribute to any
clogging that may occur.
Lime carbonates will also show up in the light beam test provided that no fertilizer
salts are in the sample. Look for numerous white sparkling crystals on the bottom of the
jar that do not mix when the sample is slowly whirled.
Soluble solids. This test is used to determine the salt level of water used for
irrigation. It is not a problem in clogging of low volume systems but'it is an issue that
can limit water sources for irrigation purposes. The test is performed with a special
electrode which is usually not available to the grower. The County Extension Agent can
advise on the subject of soluble solids.
Estimated chlorine. This test indicates the amount of chlorine solution to inject and
whether the water contains considerable organic materials. Organics can affect the ar2.urt
of chlorine used as a bactericide. Purchase a DPD type chlorine test kit that reads free
and total chlorine. There is a separate Res. Rept. CS80-1 on this method that can be used
by growers entitled "Estimating chlorine requirements."