> Humanity has always harnessed most of it’s energy extremely inefficiency via plant photosynthesis. However, the amount of food per acre has steadily grown acr

> Humanity has always harnessed most of it’s energy extremely inefficiency via plant photosynthesis. However, the amount of food per acre has steadily grown across thousands of years. A more interesting metric would be calories-harvested over calories-input. Food per acre has certainly increased. A lot of the increase is through selective breeding, GM crops, and other technological efficiencies, but a lot of it is from increased fertilizer, which is just calories/energy in a different form (fertilizer is just a store of energy -- that's literally why you buy too much of it in bulk and you're put on a fertilizer-bomb watchlist). You can grow more food per acre by throwing more energy at the problem, but that doesn't necessarily mean you're doing it more efficiently or sustainably. One way of looking at all the fertilizer runoff, for example, is it is quite literally leaking input energy out of your harvest, decreasing your efficiency.