Hi John, I definitely agree that percolation aka steady state or saturated hydraulic conductivity rate (Ksat) is a useful measure and could be included. I stayed away from it simply because it takes longer to measure and I was trying to stick with things that could be assessed quickly. In engineering school we are taught that Ksat is basically a fixed property for a given soil type, but that completely ignores the fact that biology can change it. I would certainly encourage people to check it every few years – just need an infiltration ring (preferably double ring infiltrometer for Ksat) and an hour or two to sit and watch it.