Continuing to Classify Your Water

I’ve really enjoyed the feedback I’ve gotten in the field and in email about the idea of looking hard at irrigation water. Thanks for that! And the really important thing I’m hearing is the need for understanding.  I’m doing this post from my iPad in the field, so please excuse the lack of monkeys.

Let’s continue for a quick look at three letters: TDS. Total Dissolved Solids is a really cool concept. I always have a hard time when someone says to me that water doesn’t have anything in it. It’s water, right? Well, wrong. That water has solids dissolved in the water column. We measure this in parts per million and it’s expressed sometimes in milligrams per liter… which is the same thing.

Here’s a general classification rule for water:

Fresh  less than 1,000 ppm TDS
Brackish  1,000-5,000 ppm TDS
Highly Brackish  5,000-15,000 ppm TDS
Saline 15,000-30,000 ppm TDS
Sea Water  30,000-40,000 ppm TDS
Brine  40,000-300,000+ ppm TDS

When someone starts telling me about their “saline” water, of course, we have to get on the right page for good conversation. In truth most of us are dealing with the first category and sometimes the second.

Here’s today’s fun take-away. These Dissolved Solids. They weigh something. Depending on what makes up the TDS of a water, that weight can be significant. A good water test will express this in pounds per acre-inch or pounds per acre-foot.

Three acre feet of water brings a nice application of 3,000 pounds of what is usually undesirable. A ten day stretch of big water nights brings about 15 tons of solids to your Turfgrass World.

Looking at a recent water test, I see  370.6 ppm of TDS which calcs out to just over 84 pounds per acre inch of water. So what? OK, let’s say that this particular 100 acre track gets a million gallons of water on a hot day. Just over 3 acre feet. My 84 pounds per acre inch turns into just over 1000 pounds per acre foot. Three acre feet of water brings a nice application of 3,000 pounds of what is usually undesirable. A ten day stretch of big water nights brings about 15 tons of solids to your Turfgrass World. Ten Days. 15 Tons. If this is your world, you better have a plan.

Now you know why I’m looking at TDS. In a future post, we will talk about what’s inside that big application you didn’t know you just made.

2 Responses to “Continuing to Classify Your Water”

  • Austin Allison:

    I have enjoyed reading your columns, they are very informative. I am currently struggling with localized dry spots on my bent greens. I started at the course I am at a year and half ago and inherited a 2 inch thatch layer on staight sand. The staff and I have made a huge impact on the thatch. I have tried everything I know of to rewet these areas. I have tried tablets(penetrating, retention, and the OARS tablets) punching holes, flushes, and cylcling the irrigation with no success. I have been successful with pouring a retention wetting agent (6oz/2.5gal H20) in a jug pouring it on the spot and handwatering it in. I have had zero success w/ the penetrating wetting agents. This method is fine if there are not many spots but if I try to dry them out for any reason or get caught on a dry day I pay the price and it is all I can do to keep up. I initially thaought it was the thatch layer but I am noticing it on my aerification holes as well. I did have the water tested and did not see anything excessive. If I can figure this out it will make my life much easier. Do you have any suggestions?

  • OK so…I hope you understand that there is no diagnosing problems over text. Having said that, what I see in your words is that you can be your own best troubleshooter and should be commended for working hard at this. Here are a couple questions to ask yourself as you look for answers.

    1. Have you ruled out pathogens? Fairy Ring complexes can present just like this so best to get some pathology and rule this out.

    2. If the retention agent works, have you tried a couple different ones and played with the rates a bit? Seems like there is some work to do in this area.

    3. Excessive isn’t always what we look for in water. In fact, too clean may keep real wetting from happening. How is your water bicarbonate? What about paste extract bicarbonate? You may need an acid in your world.

    4. How’s your soil conductivity? You may need a flush.

    5. And if you do flush, what carbons or carbon-based materials are you replacing with?

    This is the process that I’d go through given what you’ve told me. There may be more or less, but working through diagnosis should give you an answer at each step. Insanity is doing the same thing with the same results that you don’t want.


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