See, this would be an interesting discussion in more detail for a number of reasons... There is the available P and there is the tightly bound P that exists in almost every soil/rock in the world(to my knowledge)... Yes, P does help plants establish and is not to be disregarded at all... P is a very important nutrient which is what makes it one of the big 3... We are just considering the source and how much is needed for grass... In regards to AM Fungi arriving in a couple of weeks,,, I've heard/read that AM Fungi can frequently find the host that it is matched to within a season or 2... For grass to mine the P, that is bound up in the soils, it must have the aid of AM Fungi, becuz w/out the fungi, the plants will be restricted to the freely available P... Is that True? The other point that I'd heard/read was that when P was added to the soils,,, that the AM Fungi became rather inactive, while so much available P was present... I did not read of a reason 'why', that would happen, just that it did happen... Is that True??