Side Graft on a Root
This does not differ from the ordinary side graft except that the cion is inserted in an incusion made on the root, which is exposed by digging away the earth. The side graft has the advantage of not splitting the stock, and if the incision is made of just the right size, it may be possible to bring the cambium layers of the bark in contact on both edges of the cion.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 3 Chapter 5