Someone asked me a very similar question today. And here today, as it was then, is a response that may make sense. Or not.
February 16th, 2012.
I received this today in my email from a source that shall go unnamed because she/he/it is dumb enough to use the word 'Doctor' around my name. Kind of like using the word 'beautiful' around Susan Boyle. She can sing, however. I can't.
"Dear Dr. Wilber,
In a post in the TurfNet Turf Blog Aggregator this week, Sean McCue of Castle Pines said, "While driving around today I noticed an interesting phenomenon from applications of iron and other biostimulants to some of our trees. We have been treating a handful of weakened trees as a result of using effluent water for irrigation purposes on the golf course. We have been applying this special mixture every two weeks to help buffer the salts found in the water and soil that is harming the trees. and saw..."
I don't understand how iron and biostimulants can help buffer salts. I thought that was a calcium thing. Or were they just present in the complex applied and happened to cause the green-up he saw? Please explain.
From one of the thousands of turfies eager to suck knowledge from your brain."
Ok... so, first off, If you don't know Sean, you should. He's an amazing guy and hats off to him. He's like all those guys in Colorado, not much to do this time of year (kidding) (sorta).
When I read his whole post, it really is talking about a greening turf effect and not really the whole of his tree salt management program, so time to be general. The real keyword here is buffer.
To buffer basically means to resist change. When we talk about the buffering capacity or a buffering solution in science, we are finding ways to understand a limitation in change. So Sean is saying here that he has a brew of Iron and some bio-stim stuff and he makes apps every couple of weeks to help the trees at his place resist the changes that may come from the use of effluent water and the additional salts that come with said water.
It really isn't always just a calcium thing as far as application goes. One, the iron he is applying may make some of the natural soil calcium carbonate, that is usually very tightly held (read: highly buffered) release a bit (read: create free lime). The carbon from his biological also helps sequester salts and keep them from being plant available. So the combo of the two makes for some good results. Water doesnt affect the tree as much. Some green-up of turf happens, which may lead him to work with this technique on a larger acreage basis. Pretty good things.
In a lot of cases when we see sodium and its redneck cousin bicarbonate (read: hard water) working trees over from irrigation water, we simply test the tree well and treat accordingly. This can mean some addition of gypsum or lime or perhaps the addition of something like iron sulfate to help release what we have there. A good water test and a good soil test and someone who actually knows how to read both can do the trick.
Thanks to Sean for being a good thinker and my 'wishes to be anonymous question writer' who had a good question despite being a chicken.