I'm too familiar with soil but more so with hydro. As of now, it appears your soil is alkaline. I'm not familiar with how soil reacts because in hydro, a high PH means the plants want more nutrients because along with the skyrocketing PH, the PPM usually goes down. Sometimes both go up simaltaneously and that usually indicates something is in the resevoir that is altering the PH levels.
I'm guessing with soil you have a buildup of nutrients that is altering the properties of the soil, thus raising the PH. The best advice i could give is to flush it and go from there. Maybe post some pictures in the nursery of your plants so others can help.
