but also nightsoil, and human waste. also, organic materials near the ocean, seaweed, leaves from the forest. also, the use of cover crops and legumes, sometimes plowed into the land. all of these were important to return nitrogen and other macronutrients to the soil. but there were two things about them farmers did not always love. one was that they were labor-intensive. if shifting was labor-intensive, applying manure was, too. and it did not allow for the maximization of one land for commercial production. that is an important point. ok, we will feel that works in a minute. it did allow for agriculture to be a more land-indeterminate thing. ok, with this model of soil fertility management, we see in great britain across the 17th and 18th centuries, and emerging revolution that allowed for much more intensive agriculture on a fixed pieces of land, sustainable over the long-term. i will explain this quickly, it is complicated. but what it involves replacing fallowed land, land out of production, replacing it with a sort

what happens to the rest of the world with the use of nightsoil and horse manure? organic,e to be so increasingly we have indoor wasteng, that takes our away, where these critical nutrients become what we call pollution. also cease to have so many horses in cities, and cease to have the manure problems as well. to travel theg world over to find these concentrated forms of nitrogen pollution. let me end by pointing out, sorry again, a slide behind, how haber-bosch process transforms the nitrogen cycle. today, industrial nitrogen fix asian through the haber-bosch process, produces about 32 million metric tons. of the intentional contribution of legumes -- we also get nitrogen oxide from boston, another 25 million metric tons. combined, and you can do the math here, we are looking at about over 157 million metric tons but a human produced. the natural nitrogen cycle 110lf only cycles about million metric tons between land and air. so the human nitrogen cycle has become bigger than the natural one. >> what industrialization would diet,ffect, the changing -- withng nigh