Fertilizer

S13, E23: Humans flush it, cows dump it, and two million ton machines scoop it from the ground. Without it one third of us would starve. Modern Marvels "Fertilizer" tours the places that harness the vital nutrients that enrich the soil...that grow the crops...that feed us. We'll get knee high in a food-scrap dump, dig deep in a phosphate mine, sniff around a sewage treatment plant, (yes, human excrement makes excellent fertilizer) and get our hands dirty in a trough teeming with seven million hungry worms. And we'll go back in time - when fertilizer was so precious that a war was fought over the control of bird poop. Get ready for a nose-rotting whiff of fertilizer.