Note: Farming in that manner regularly is not sustainable. Also, at a certain loss point, you might as well compost the crop back into the soil to contribute to next year's crop as fertilizer. That stuff is expensive.

Hell, the entire economy makes no guarantees at being sustainable in the long run. The unsustainability period just shows all indications of being longer than a human lifespan, thereby making it easy for people to write off as not their problem.