It is best to obtain samples during the late spring and summer when the demand for irrigation water is greatest. A representative contamination-free sample is necessary because the accuracy of the water analysis is only as good as the sample. No pesticide, surfactant, or fertilizer containers either. The container and cap should be rinsed at least three times, prior to sampling, with the water to be sampled. The laboratory needs a quart of water for a complete analysis.
Air can alter the pH, carbonate, and bicarbonate levels of the water.
Aquatic plants and microorganisms can alter nutrient levels and pH of the water if not refrigerated. Identify each sample with a permanent label resistant to moisture. Laboratory Analysis Chemical analyses differ from laboratory to laboratory, but most labs cover the basics B pH, bicarbonate, carbonate, electrical conductivity, sodium, chloride, calcium, magnesium, potassium, iron, and boron. Several indices are calculated from these constituents that determine whether the irrigation water will be detrimental. 1.25 is utilized routinely.