Good water sampling techniques are an important first step in obtaining a meaningful water test. The following guidelines are intended to present the basics of water sampling.
Water should be collected in a clean plastic bottle if a general irrigation suitability test is required. However, metals such as iron and manganese may precipitate out if the analysis is delayed. Gathering a separate 4 oz sample in a separate sterile container with a few drops of acid to a pH below 2.0 will minimize this possibility.
If the water is to be tested for coliform bacteria, separated sferile container (100ml) should be included as well.
DETERMINING THE PARAMETERS TO BE TESTED
A & L's "irrigation suitability" package (W2) will test for pH, electrical conductivity (soluble salts), calcium, magnesium, sodium, potassium, phosphorus, carbonate, bicarbonate, nitrate, sulfate, chloride, boron, and total dissolved solids. The adjusted sodium adsorption ratio (adj. SAR) will also be provided. Other tests may include iron and manganese (W4), sulfide, residual chlorine, total suspended solids, and microbial counts. Acid titrations may be run to determine injector rates to reduce water pH to an acceptable level. Specify type and grade of acid to be used.
COLLECTING THE WATER SAMPLE
A pint of water is generally enough for a standard irrigation water test. Avoid air spaces in the bottle when collecting. Annual sampling may be necessary to monitor trends. Sampling at the end of summer may indicate water quality at its worst.
Well Water: Collect only after pumping for at least 10 minutes, to allow for a representative sample. It should be taken directly from the well source before any contamination can take place. On occasion, it may be necessary to test the water at different points along the line: before and after the injector pumps and filter station, or at the end of the line to determine residual chlorine or pH for instance. Sample accordingly.
Surface Water: Avoid taking samples directly from the sides of the holding area. They will not be representative of the total body of water.
Lagoon Water: If lagoon water is to be tested for irrigation suitability, request test package W2. You may want to consider having the sample tested for ammonium nitrogen as well. Lagoon water often contains significant levels of ammonium nitrogen that should be accounted for when you irrigate. A & L Laboratories also offers a lagoon nutrient test package, which measures levels of ammonium nitrogen, nitrate nitrogen, organic nitrogen, phosphorus and potassium. A nutrient analysis along with an irrigation suitability test will provide a complete picture of lagoon water quality.
Identify each sample with numbers and/or letters, by time or position of sampling for example, or good versus bad. Avoid numbering samples simply as 1,2,3 ... as it may lead to confusion later. Indicate the analyses desired and provide information that may be of use to the lab in determining problem areas. Other tests may be recommended.
Keep sample cool (do not freeze), tightly sealed, and ensure that the sample arrives at the laboratory within 24-36 hours. Include a completed water analysis information sheet or cover letter with instructions within the same package. Processing will be delayed if sent separately. Also, include payment if you do not have an established account.
SEND SAMPLES TO: A & L Western Agricultural Laboratories, Inc.
1311 Woodland Avenue, Suite 1
Modesto, CA 95351
Phone (209) 529-4080 • Fax (209) 529-4736
Oregon Office: 10220 S.W. Nimbus Ave., Bldg. K-9
Portland, OR 97223
Phone (503) 968-9225 • Fax (503) 598-7702