The active irrigation season is underway, so let’s pause briefly to review why irrigation water quality testing is important, the value of proper sampling, and what to look for in test results.
Links to seven resources on the topic follow this brief summary. Reviewing those and similar resources is a good idea.
To summarize, irrigation water can:
1. Have a mineral or chemical composition that damages soil, irrigation plumbing and equipment, or crops directly. That same composition may also lower the effectiveness or complicate the use of other inputs such as fertilizers of crop protectants.
2. Contain plant pathogens.
Of course, using the same water source to wash produce and/or fill spray tanks can raise additional unwanted possibilities.
Regardless, the bottom-line is that irrigation water quality affects growers directly and indirectly and in the short- to long-term.
Testing the chemical and particulate (nonliving) composition or characteristics of water used for irrigation is relatively straightforward when major recommendations are followed. Keep the “garbage in-garbage out” principle in mind and collect, handle, and submit your water samples carefully. Also, be mindful that special steps are required for sampling surface (pond, stream/river) versus well water. Consult your testing service for specific guidance, if needed. Testing for plant and/or human pathogens is also important and consulting a plant pathologist and/or human health and food safety specialist is recommended. As you know, Drs. Sally Miller, Melanie Ivey-Lewis, and Sanja Ilic with The OSU are experts in these areas.
Test results of the chemical characteristics will often include the levels of: pH, total alkalinity, hardness, electrical conductivity, total dissolved solids, and multiple elements. The importance of and acceptable ranges for each are outlined in resources linked below and other publications.
Soil and plant testing are common – consider testing irrigation water, too!
https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1160&context=anr_reports (focused on nursery and greenhouse crop management but also a good reference for vegetable growers)
Knott’s Handbook for Vegetable Growers (https://www.amazon.com/Knotts-Handbook-Vegetable-Growers-Maynard/dp/047173828X) also has five pages of handy reference tables on irrigation water quality, including regarding crop tolerance to various characteristics of irrigation water. Contact me for more information, if needed.