Here's what I use for root development in replacement for K in N-P (K). RGS and it's all science and have been proven. I've used this last year along with the Humic12 and my lawn looks healthier and greener than most lawns in my neighborhood. when I first moved in it was full of weeds and what not and the lawn was in pretty bad shape since the previous owner moved out 1 year before and the lawn has been sitting with no fertilizer or amendments and has never been watered except whatever rain they had that year.
and here's the info for the Humic12
here's my lawn from last year
