tilling to deep

so I have seen the dangers of tilling to deep talked about in some books,
they idea they have is that if you till the ground deep enough you bring up the soil that has no organic matter in it,
and that just hurts things when it is mixed in...
and I finally have an example of that,
the near and far grain plants are doing well, but all in the middle are almost planted in total decomposed rock, the right 1/4 of the picture is just the weeds, so look to the left in the picture

I had to decide when it was not so much dirt and to much rock as to when I quit tilling,
it was tilled to deep there in the center.

so check how deep the roots of the local grass go down to see how deep you should be tilling,
and usually this is not an issue in california and the american southwest because there is no good soil to dilute with the soil that has no organic matter in it,
but many areas have that issue,
and now I have seen it for myself.