Well, good. That 3.7 dS/m sure sounds a whole lot more like what I would expect from a green waste compost. I'll say it again: I think there was a mix up somewhere. 3.7 is still a little high for some plants but isn't going to kill anything. A few thorough irrigations and/or rain events should get it down below 3.0 in the root zone, which is safe for just about anything. Just be sure to monitor moisture carefully all the way through the root zone to ensure that it is allowed to dry slightly between irrigations. If it is already saturated when you apply more water, the effects of leaching will be impeded. Prolonged saturated conditions can also lead to an anaerobic environment as well as favor the pathogens responsible for root and crown diseases. With that in mind, the boron may be in less soluble forms which, as you stated, aren't available to plants. The key phrase when you talk to the lab is to ask for the boron value in "parts per million in extract". They may charge you extra for that number since it wasn't part of the package you ordered. However, if they ran a saturation extract (which is likely how they got their salinity and sodium values) they probably have the boron number and others on hand but they only report what you've paid for. I wouldn't sweat the pH too much either. Plant response is going to vary depending on species and variety. Plants sensitive to alkaline soil conditions will probably be yellow, particularly on younger growth and they may not grow very fast. Depending on how sensitive, growth can end up severely stunted and yield can be affected. However, 8.6 won't kill anything. And as you stated earlier (Good job on your homework!) the alkalinity can help tie up any boron that may otherwise be soluble. Another thing to consideration is that the pH of compost will usually shift towards neutral over time. I would guess that a lot of your nitrogen is still in the ammoniacal form (NH4). As that converts to nitrate (NO3)the pH should decrease, if that is indeed the case. However, high pH in a finished compost is not unheard of. If it is fully composted, and the pH is still that high, an addition of sulfur may be warranted. Sure, lots of plants can handle an 8.6 but just about anything would prefer a lower pH. (And their is also that soluble boron to consider) I'm glad the growth trial sounds like its going well so far. You'll still want to keep an eye on it for a while though. Often the symptoms of boron toxicity take a while to show up because boron accumulates in the tissue over time. But let's wait and see if you can get that extract value for boron before we draw any real conclusions. However, the growth trial and the salinity value are very encouraging.

The soil pH is good, most plants do quite well with a soil pH in the 6.2 to 6.8 range because that is the range most nutrients are most readily available. P and K (Phosphorus and Potash) are somewhat low and may well be not too readily available depending on the level of organic matter in the soil, a good source of P and K is compost, but then compost is a good source of most everything. What is the level of organic matter, humus? Something I forgot about earlier for some reason.

What do y'all think? That you don't seem to have much of a problem (consider yourself fortunate). Sure, the potash may be a touch low if I'm reading it right, but it should be fine for grass with organic feeding. Use soybean or alfalfa, both do contain some potash. With the alfalfa going down at a higher rate to hit the 1 pound of nitrogen at a time limit, you'd get more potash. Personally I'd use the cheapest. :-)

Cation Exchange Capacity (CEC) is a measurement of how certain nutrients (Calcium, Magnesium, Sodium, etc.( are held onto by the soil particles and/or organic matter in the soil. Clay soils and soils with high levels of organic matter tend to have higher CECs then do sandy soils. At 0.32 percent your HM, soil humus level, is quite low and I would suspect your soil is compacted which hinders plant root development. I would concentrate, right now, on putting down materials, compost and other forms of organic matter, that will help bring that up to open up the pore spaces between the soil particles so the plants roots can move around and thicken the turf grass easier. Blood Mea is tricky to use since the Nitrogen is so readily available it can easily burn and plant. Here is a link that might be useful: About CEC