ph is highly important. there is a chart somewhere that tells what nutrients absorb at what ph level, and at 6.2 all nutrients are availiable, anything off from that and certain nutrients can't be "reached" or processed.
imagine 6.2 is a plate of food at the perfect reach to grab everything on it, and for every .1 ph level that is off, the plate moves in front or behind you by a foot. now you cant reach everything on the plate, only some of the stuff. that is how PH works. at 6.2 the plant can use all nutrients given to it.