How much is too much sodium for drip irrigation water?

Our well tested at 230mg/L for sodium. On most everything else it's great. What can be done about the sodium -- or is it a problem?

Or are we talking sodium chloride ?


David

Compared to sea water, which is about 14,000 ppm, your 230 ppm doesn't look so bad. It would take a long time for sodium to build up at that rate. Which brings us to the important question -- how much evaporation do you have going on? Do you live in a desert (like Las Vegas) where this is the only water your trees will get? Where you have 4" of natural precipitation and upwards of 70" of evapotranspiration in a year? Then yes, that might be too much sodium.

But if you live in an area with more than 20" of rain a year, that's probably going to be enough natural flushing of the sodium from your well water that it won't be a problem.

If Stephen is referring to the same problem I have experienced what he is referring to is the fact that the hard water deposits build up on the emitters and the water flow slows or stops completely. That has made me pretty much give up on using drip. One of the drip supply companies sells a set of magnets that attached to the water supply line and supposedly will even reverse the build-up. I have not tried it but if anyone else has I'd really appreciate hearing about your results.

Hard water deposits are from calcium, not sodium. But usually where you find hard water with a lot of calcium in it, it can also have a lot of sodium as well.

Vinegar can be used to remove hard water deposits, and were you to add it to a drip irrigation system, it can also benefit the plants. There are a lot of soil critters that can metabolize vinegar.

John, thanks for the clarification. Any ideas on how to and how much vinegar one would use. Would one of the syphon fertelizer injectors that is attached to the hose bib do the trick?

John Elliott wrote:Compared to sea water, which is about 14,000 ppm, your 230 ppm doesn't look so bad. It would take a long time for sodium to build up at that rate. Which brings us to the important question -- how much evaporation do you have going on? Do you live in a desert (like Las Vegas) where this is the only water your trees will get? Where you have 4" of natural precipitation and upwards of 70" of evapotranspiration in a year? Then yes, that might be too much sodium.

But if you live in an area with more than 20" of rain a year, that's probably going to be enough natural flushing of the sodium from your well water that it won't be a problem.

Well, that's what I am hoping. Avg annual precip in the area is 27 inches, all in the winter (northern California). So that means I am irrigating a lot, but only during the summer. This year, I hope to build all the necessary components for rain water storage so that I will be able to use rainwater from now on.

I like the comparison to sea water. It makes me feel very good about the sodium report.

In our water, we don't have excessive amounts of calcium or anything else. Just boron, which is another issue. (4.5mg/L).

David Stratton wrote: Would one of the syphon fertelizer injectors that is attached to the hose bib do the trick?

It's worth a try. I'd start out with the highest setting and then dial it back every few days or so until you get to the point that the vinegar keeps the line clean, but you aren't going through your supply of vinegar very fast. Your mileage may vary.