Hello Howard, that is exactly how I understand things as well. +2Ca and +2mg can easily out compete +1K. I realize this plays a role in the difficulty of getting K to stick, but it would seem to me if there were empty sites on the exchange sites and plenty of them that this competition issue would be less impactful. In my situation I have a soil that is supposedly TEC of 7 when experiments on my property show me that the soil has more of a TEC of 12-15 and potentially higher than that. If I could add 1500ppm of Cal on top of the 1000 it already has and it would stick for years on end it would seem to me that there are a lot of empty exchange sites and thus K should not have an issue finding a site to bind to since I’m not going to throw on an additional 1500ppm of Cal. This again is why I’m questioning CEC as there has to be deeper insights here because things just don’t make sense to me. I clearly don’t understand something but it appears to me that the ideas on CEC you can read about online are incomplete.