[tfyoung]

> Corn kind of reproduces itself every year (If you don't get the GMO kind), so you only need natural resources to continue to grow it right? Water, sunlight and labor?

At industrial scale, it has a huge petro-chemical fertiliser input.

[pfdietz]

Total energy input to agriculture in the US is less than 2% of total energy consumption. So "huge" there has to be taken in context.

All the energy inputs to agriculture could be replaced with non-fossil inputs. Fertilizer in particular needs hydrogen to make ammonia, but that can be produced from non-fossil sources.