When was the last time anyone did a pick your field practice? I was taught it when learning and usually it was down to 100-200ft and then power away. I continued to do it to keep my hand in (especially when flying different aircraft) PA-38 rate of descent raised my eyebrows but I was probably over-compensating to avoid getting anywhere near stall speed.
Looking at the picture, appears to be evidence of heavy braking on left mainwheel, uneven ground, heavy braking causing nosewheel loading and collapse with just enough inertia to flip the plane.