g'day paul,

it'll work just as well added on top of the medium, how i end up using it most times.

len

Here is a link that might be useful: lens garden page

It is much better to incorporate than to broadcast CRFs. Nutrient release is temperature driven and directly exposing the prills to the sun can cause erratic and rapid release of nutrients. At a minimum, you should scratch it into the top inch or two of soil for best results.

Al