Becky, thank you for the quick response and advice. I will continue with the Milorganite and look up synthetic ammonium sulfate fertilizers.

For the next soil sample I will use your vinegar test and ask for the ammonium acetate if needed.

I wouldn't go out of my way to find ammonium sulfate. If I were at the store and there was one fertilizer with urea and another with ammonium sulfate and other things being equal (price for example), I'd pick the ammonium sulfate for an alkaline soil. If your soil is limestone based, it will say "Ha, ha, I'll neutralize any acid you throw at me." Decomposition of organic matter is acidic. Rain is acidic (about 5.6). Mulching leaves is good for many reasons, besides the acidifying you would get when the leaves decompose. Your irrigation water seems very alkaline. I wonder if your pH will vary depending on how much you have to irrigate. Many people grow great grass with alkaline soil, so don't worry too much about it.

I've never heard of water with that high a pH. Seems like you'd see signs of damage or discoloration on everything that gets wet. Does it render fat to make soap?

I did a little reading. There is a difference between water with a high pH and alkaline water. The alkalinity of the water is a measure of its "liming effect" and has to do with what's in it like bicarbonates. Water with high pH isn't a problem but water with a lot of alkalinity can affect the soil. Maybe your water treatment company can tell you. It is measured in mg/l or ppm of CaCO3. Also, on ammonium sulfate, if you use it, be sure to follow instructions on the bag as it can burn the grass if applied improperly.

L.D. McMullen is the treatment plant. The data is in the link below

http://www.dmww.com/water-quality/water-quality-data/

I sent them an email to ask as that data is not on the webpage.

Great, thanks for taking the time to help me understand.

Here's the response: "CaCO3, calcium carbonate, concentration of McMullen Finished water yesterday was 80.12mg/L."

Now what does that mean? I know that mg/l is the same as ppm. But what does that say about how much the water is contributing to your alkaline soil? Maybe post a question on another thread. I know of a chemist on here but he may not be reading this thread. How much CaCO3 equivalent you're getting from the water would depend on how much water you apply. I wonder if there is a way to convert this to gallons. In any event, it is contributing something.

Found something of interest: bicarbonates in irrigation water

One of the slides called Water Quality listed <40 as good, 90-120 as increasing problems, > 125 generally not suitable

So at least yours falls under the limit for "increasing problems." Keep in mind that Morph suspected you may have calcareous soil, meaning it's going to be alkaline no matter what.

@becky: You can calculate the amount of CaCO3 applied to the lawn from the 80.12 mg/l figure, as you indicated. Multiply that figure by 3.79 to get 303 mg/gal. If you apply 1 inch of water to each 1000 sf, that comes out to 623 gallons. Multiply the two and convert to lb and you get 0.41 lb CaCO3/ksf of lawn. What's a typical % calcium carbonate for lime? Whatever it is divide it into the 0.41. Let's just say your water contributes about a pound of alkalinity as CaCO3 each time you water, so maybe not a big deal.

I think high pH water like yours can be neutralized in couple of days just by letting it sit in a container (not that you could do that). The CO2 in the atmosphere reacts and is enough to drop the pH a lot pretty easily. I imagine it's about a wash, so to speak between your water and rain/dew that will neutralize it.

In addition to adding all the things becky mentioned in order to reduce pH and/or improve the soil tilth, you could add sawdust. Sounds odd, but it is supposed to be great for soil structure when it breaks down. Morpheus used to recommend this.

You don't want sawdust with anything like glues in it. The best thing is a product like Equine Pine, which is compressed sawdust pellets for horse stables. I got some at Tractor Supply one time for $5 per 50 lb bag. I put down a full 50 lb per ksf with my spreader opened wide up. It will quickly dissolve into the soil and a week later you won't even know it was there. It does take a long time to break down and you don't want to till it in as it will rob nitrogen from your grass. On the surface it will get the nitrogen it needs to break down from the air ... Just a thought. It's something you might add once or twice a year.

Thank you both for the information.

danielj, a local tractorsupply store sells pine pellets $5.79 for 40Lb bag. I will add the pine pellets to my plan.

Your soil is buffered. A highly buffered soil will resist pH change. In a poorly buffered soil pH will bounce around anytime something is done to change pH. How buffered is yours? A CEC in the 20s would indicate highly buffered. Morph thought it was probably closer to 15, which is still fairly resistant to pH change but it can move. The ammonium acetate test next time will give a more accurate number. Daniel has given some good information on lowering the pH of your water by letting it sit around. Many herbicides break down in an alkaline water and should be mixed with a neutral or acidic water. Next time you need to mix up something, you could let the water sit around in shallow containers for a day or so and that will help lower the water's pH.