Water Analysis: Units, Terms
and Sampling
Numerous parameters are used to define
irrigation water quality, to assess salinity hazards, and to determine
appropriate management strategies. A complete water quality analysis will
include the determination of:
1) the total concentration of soluble
salts
2) the relative proportion of sodium to
the other cations
3) the bicarbonate concentration as related
to the concentration of calcium and magnesium, and
4) the concentrations of specific elements
and compounds
The amounts and combinations of these substances
define the suitability of water for irrigation and the potential for plant
toxicity. Table 2 defines common parameters for analyzing the suitability
of water for irrigation and provides some useful conversions.
When taking water samples for laboratory
analysis, keep in mind that water from the same source can vary in quality
with time. Therefore, samples should be tested at intervals throughout
the year, particularly during the potential irrigation period. The Soil
and Water Testing Lab at Texas A&M University can do a complete salinity
analysis of irrigation water and soil samples, and will provide a detailed
computer printout on the interpretation of the results. Contact your county
Extension agent for forms and information or contact the Lab at (409) 845-4816.