A meeting of horticulturists in Iran in the 1970's issued a statement that peat moss is a non renewable resource. The British Hortucultural Society is asking its members to cease using peat moss because harvesting of it is unsustainable. Unless you live in a desert, or the plains, where few trees grow there are better, renewable resources that can be used, often at less cost, to improve soil. I watch people aound here diligently rake up, bag up, and actually pay to have these leaves that fall from trees every year, hauled away every fall and then in the spring go to the garden center and buy bags of peat moss to replace the organic matter they threw away the previous fall. I watch people around here diligently collect the grass clippings when they mow, bag them, and pay someone to haul them away so they can go to the garden center and pay for a few nutrients to repalce the thousands they just tossed out. Like buying white bread made from flour that has 25 nutrients removed during milling and has 10 nutrients put back in and is called "enriched". In Indiana there should be no good reason for someone to buy peat moss to compost manure.

i would start the diagnostic process .. by determining if they are getting water .... hand trowel.. small hole .. find out if water is actually getting to the root zone of the one that is struggling ... you have a lot of mulch ... if you are NOT watering deeply .... you may not even be getting through the mulch ... starting the diagnostics at the far end of the spectrum.. and considering chemicals ... organic or not .... would be the absolute last thing i would consider .... ALL newly planted transplants are subject to leaf color change in the heat of summer ... of their first and second years ... the roots were either complete truncated [ball and burlap].. or have not settled in enough to offset the heat of august ... they just cant pump enough water ... in the alternative.... is it too wet ... hence the small hole .... find out what is going on in the soil ... good luck ken

Possible they are using manure as an ingredient in the compost and the farmer used lime to keep down odors in the barn. Not an uncommon practice. For the OP: 8.3 is calcium carbonate (limestone found in the typical bag of lawn and garden lime). Possibly what you have there. I would expect some movement toward neutral as it finishes, but who knows how long it would take. You can keep checking if you have a pH meter and if it stays high and seems to be affecting plants, use slightly acidified water when watering. 7.8 is not that high though, I'm not sure I'd mess with it unless you're trying to grow azaleas or blueberries. The high K may be from the compost but also could be coming from the fertilizer you used, depending on what it is. My garden soil has high soluble K but it doesn't seem to hurt anything. And it will leach away over time in your containers. This post was edited by toxcrusadr on Tue, Jan 6, 15 at 11:28

Adding salt (NaCl) will not create any kind of a buffer. pH buffers require acids and bases (weak ones) and conjugate salts in certain proportions. The problem is in trying to accurately read the pH of distilled or RO water as a way of checking a meter. You just can't use distilled water for that since its pH is so easily disturbed, and if you add anything to it, it's not distilled water anymore. Distilled water is however the proper ingredient for adding to soil to make a test solution for measuring pH, or for making pH buffers or calibration solutions. It's a buck a gallon where I live so I would never bother making it. There are, as I mentioned, some calibration check solutions that are easy to make at home, but since your meter doesn't work on liquids, about the only way to check calibration is to test the same sample with pH paper and the meter and compare results.