soil for cutting roots???

i do a little bonsai on the side...bonsai growers put sharp things in soil to help with root cutting{splitting}to promote better nutri ubsorbting...i do this myself....dont realy see anone writing on the subject...any thoughts???sharp stuff..ie. sharp sand,realy small red lava{crushed red lava} just like pruning top.. more root tips better ubsorbtion of nutri...works for me..also keeps pot size down,but get same results as using bigger pots

try an experiment. one started with sharps and one without. i've heard of this done with diatomaceous and egg shells but i'd be interested to see the direct results.

snap some photos.

i dont need to experiment,,its what i do.my soil mix contains potting soil,sharp sand{not playground sand}cruched red lava,and perlight..this is a soil grow typical cfl small stelth..never need more than a cut 2 liter bottle,i have had some get 33in but ilike to keep them around 25in max..not a lot of space