Brock Ulfsen wrote:

....
Also, modern hybrids have shorter stalks, and thus lay down less carbon
per acre than heritage varieties.

Not really, for the most part--hybrid wheat, corn, soybeans all are
essentially the same size plants as always. What crops specifically are
you thinking of?

Plus, most hybrids are grown in much higher "plants/acre" than were
their predecessors--both narrower row spacing as well as plant spacing
in order to produce higher net yields...

.....