There are similar numbers for conventional farming, and historical estimates too. There's a whole field of study on the EROI of agriculture. And yes, for all of human agriculture until roughly the industrial revolution, the EROI was over 1. By definition. 1 unit of labor + sun better equal at least 1 unit of food! When solar energy is the only external input and all mammalian labor provides the rest (which must be fed by the same crops that you're trying to grow), if you got less crop calories than it took to run the farm, you and your livestock would be dead.