Elizabete, In my experience the little pellets don't always dissolve. Some will turn transluscent color and others will stay the same. If you take one and squeeze it a little you will find that it is probably an empty shell.
I've never heard of over-fertilizing in cool, dry soil. I suppose it's possible, but if it's cool I would think the time release would not release anything or release less. I know that here in Florida that the Osmocote can over-fertilize in our heat when it becomes too hot. It tends to explode, releasing all of the fertilizer. That's why we use Florikan products, it doesn't do that. I'm not sure about Osmocote, but the Florikan needs moisture to be activated before it will release with the temperature.
