Benjamin Squier
Everybody knows it was Herbie Hancock
You're right, that is the range for soil, wish there was a definitive range for promix. Been on all kinds of forums and people's answers are all over the place. In terms of run-off; I did it a couple times when they were younger but I read it wasn't very reliable. I plan on picking up a soil ph meter today or tomorrow to see what my ph is at the root zone.
You can do a slurry test. For the Nectar line, it's what they recommend.
Wait till the soil is dry, dig down an inch or two (don't catch your roots!). Obtain two ounces of soil, place into jar/receptical. Add equal amount of pH neutral water. Mix and let fully integrate/coagulate/penetrate. Take pH test and you have soil acidity/alkalinity results.