I see no reason to. The only reason might be for a soil that has so little potassium that plants cannot stand up, but even then that can be corrected with stuff that is much less expensive.

duane, have never used that particular product, but do know that silica can make a big difference under some conditions. I started using it regularly for my container plantings and seedlings last year. The results were sturdier plants, with greater heat and drought tolerence, and no problems with powdery mildew on the zinnias!

I've not been tempted to apply it to my veggie garden as I have no reason to think that the clay soil is deficient.

What are you using it for?