Can small-scale backyard gardening produce more food per acre than broadscale [grain] farming? Mark Shepard in his book &quot;Restoration Agriculture&quot; proclaims

[...] small-scale backyard gardening which has shown in study after study to produce more food per acre than broadscale grain farming.

Unfortunately, he doesn't cite any studies or goes into more detail. Is the main point here that grain farming is particularly low on biomass production, or is there a reason why backyard gardening can in generally have higher yields than industrial farming? References would be very welcome!
Efficacy of food production per square foot/acre differs from soil quality and rate of regeneration. It's also a case of if you can produce year round. Some permaculture specialists, monitored one case in an article of &quot;Green America&quot; A 500 sq foot garden producing 300 lbs of produce per year. Among other's. Soil nutrient recycling is a key aspect of producing food year round, along with temperature (Green houses).

Composting
Soil/air temp
Growth rate of produce involved
So the answer is &quot;Yes&quot; if dedication is involved.