I was hoping to pick your brain on gypsum for a moment. How much gypsum do you consider to be the maximum per application? I am assuming it is like lime where you can easily overdo it? I am trying to treat a large arborvitae that is right next to the road and the soil has been confirmed to be very high in Na. Soil test was done in July so just imagine how high it was just after winter. Soluble salts came back low on this test, not sure if they already leached out or what. Soil is pretty compacted so I am thinking of incorporating some gypsum in there this fall with the Airspade and keeping an eye on it. As for how much gypsum to apply, the tree is 26" DBH with approx 40' crown spread.. Any info would be much appreciated.