white 'crust' on soil?
I've been container gardening for a few years now, and towards the end of every summer I start noticing a whitish crustiness on the soil top, sometimes leaving a ring around the top inside of the container. I've figured it's just that the soil's nutrients have been used up by the end of the season or that remains of fertilizers have built up, or something to do with the heat through the summer.
Well, it's barely May and my tomatoes were only transplanted into their current containers 2 weeks ago, and yet I'm noticing that 'crust' starting to show. Though the soil came infused with fertilizer, I've not added anything to it, just water. I've used Schultz Moisture Plus Soil, and the plants are in 30oz cups, not ready to transplant out for another 1-2 weeks.
Any ideas what this is? Is it a problem or sign of something?