Today, our lecture is on agriculture and the fertilizer revolution. We began this course talking about agriculture with regards to the unending frontier, the expanding across the world, and the birth of the plantation complex in tropical regions. Another critical storyline and the environmental history of agriculture has been agricultural intensification. The growing, intensifying landuse to get more crops out of those lands. This coincides with the industrial revolution, which created a real need for those in europe and the United States to really concentrate on increasing Food Production to escape the trap, thinking that population would grow faster than a Food Production. There was the green revolution, where modern agriculture and genetic engineering was introduced to the developing world. Today i want to talk about the 19th century and the fertilizer revolution. In a most general sense, a shift away from close to systems of agriculture, soil fertility was raised within the farms and various ways. And we will talk about that. It was changed to a and open system where concentrated forms of soil fertility were imported into the farm. They were mined and brought out to the farms, used intensively, and would pull nutrients off the farm, out of soils, and away from the land. This became an open system of Nutrient Cycling. I want to use this term, i got this also from karl marx. By metabolic rift i mean a break in the chain of Nutrient Cycling first on the farm and then between the city and the countryside. With traditional sources of fertilizer becoming waste and new sources of fertilizer needed. What we will see then is the industrialization of soil fertility. The transnational story, i will tell it that way, with a focus on the United States. Before talking about that, lets step back for a minute and look at what soil and soil fertility is. Soil is one of the most important natural resources. It is the result of several processes. The first is simply the breakdown of what is called parent material like rock and sediment into loose matter that provides minerals for plants to grow. The second is the breakdown of organic material which combines with this broken down parent material and gives soil its physical, neural structure. Finally, recognize soil as a living thing. There are all sorts of insects, worms, microorganisms at work in soil that are critical to plants and crops growth. Soil characteristics are biological, physical, and chemical. Plants need all sorts of things to grow, it is pretty basic. They need sun, water, carbon dioxide. But they also need nutrients, macronutrients in particular, like nitrogen, phosphorus, and potassium, the holy trinity of effective fertilization. They also need micronutrients, we wont talk about those as much today. Most macronutrients come from the breakdown of soil, but the most troubling one would be nitrogen. That is at the heart of todays story. Lets talk about the nitrogen cycle, i know this is a history class, but it turns out it undergoes a dramatic historical change during this period. It is a cycle of nitrogen between land and atmosphere. This is worked out largely in the 19th century. Before that, people did not fully understand the nitrogen cycle. We now know the atmosphere itself is about 79 nitrogen. That atmospheric nitrogen is a critical source of nitrogen for plants and plant growth. But it is not immediately available to plants. And this is the most critical point we have to make, it is locked up in this n2 at him. They cannot breathe nitrogen, so it has to be made bioavailable to them. I think we talked a little bit about this before. One is a lightning, which can fix nitrogen in the soil, that is an unimportant part of the cycle, but worth knowing. The other two ways are by soil microorganisms. Some of which are symbiotic with a type of plant called a legume. They have the capacity to pull nitrogen out of the atmosphere and put it in the soil in ways that make it available to plants. To the planting of leguminous plants like peas, soybeans, peanuts, blackeyed peas, lentils, these were all crops that have the capacity to fix nitrogen from the atmosphere into the soil. There are also nonsymbiotic bacteria that can do this, as well. But legumes are critical. The earth has a natural nitrogen cycle, nitrogen is constantly cycling in the atmosphere and in the soil. It is a result of decomposers, taking bacteria, and denitrifying bacteria. Bunnies apparently help in this process. [laughter] what i want to emphasize, one of the products of the metabolic rift i referred to, is the human transformation of the nitrogen cycle into the 20th century. That may not make a lot of sense to you right now, but i promise i will get to it and explain it in some detail. But were getting ahead of ourselves. Lets talk about the critical problem here, how do farmers over time maintain soil fertility on the lands they are farming . And before we get to this fertilizer revolution, i want to suggest a of ways in which they did that. Perhaps the most important, early on, was shifting cultivation. By shifting cultivation, the dominant mode of fertilizer management worldwide. It was an approach whereby farmers would clear it a piece of land, usually for us, usually using fire to burn off and make nutrients from organic material immediately available. It turned out that the fire and the ash produced has a basic ph which could correct for acidic soil. Farmers would then farm that cleared land for a certain period of time, taking advantage of the natural fertility in the soil. When the fertility began to wane, farmers would move on and clear a new piece of forest and let the oldfield revert back. They might come back around to it, but decades later when it had regrown backup and restored its capacity to be fertile as a result of that regrowth. Practice on a small scale, was reasonably sustainable, and not that damaging, ecologically. Though it was and still is a landintensive way of farming. It required a lot of land. Another way to think of it, for the little piece being farmed at any moment, there has to be a lot of land available so the farmer can then migrate. Does that make sense . That was one of the most important ways in which farmers managed soil fertility in the past. And typically in tropical regions. We will talk about why that is the case in later lectures. Turns out tropical soils, burning is a good match for them. Having focused on slash and burn as a strategy, a tremendous number of American Farmers also practice this, particularly in the American South. That was where plantation crops were grown like tobacco and cotton. Farmers would farm the land until its productivity was worn out, and then they would move on. This actually created a caricature of the southern farmer as a soilmined. Someone who did not care for the land, went out and cleared the land, took the nutrients out of course, they were growing staple crops like tobacco and cotton they would mine the nutrients and then move on. A lot of agricultural farmers and others who valued the stable, sedentary agriculture saw this as a particularly slovenly or wasteful they would not say destructive, but that is what they meant. There was an attachment in places like the American South to being more settled and civilized. And his brand of agriculture seemed messy. It actually seemed a lot like native american agriculture. They practiced slash and burn cultivation for the most part. Also, forest fallow. A farmer might own thousands of acres of land, but only farmed a little at a time. That farm base was there so they could cycle their arable land throughout a 20 year cycle. It did not look good, but it was potentially sustainable. And of course, this land use and soil fertility management system, combined with slavery in the south, southern farmers were particularly interested in maximizing their investment in slaves. To do that, they had to get as much productivity out of the land as possible. In the context where there was a lot of land to be had, and there was not a lot of labor to be had. There was an economic logic rooted in slavery to the alliance upon shifting cultivation of the Strategy First soil fertility management. Clear so far . Questions from anyone . I will charge more to the interesting stuff. Another way of managing soil fertility, i will mention this quickly and move to another system. It is to manure. What do usually think of, when you hear the word manure . Animal manure. I include fallowing here, you would farm a field for a while and let it rest. Probably not enough for agriculture to be sustainable. A lot of farmers required ground manure. But also nightsoil, and human waste. Also, organic materials near the ocean, seaweed, leaves from the park. Also, the use of cover crops and legumes, sometimes plowed into the land. All 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, they were laborintensive. If shipping was laborintensive, applying manure was, too. It did not allow for the maximization of one land for commercial production. That is an important point. It did allow for agriculture to be a more landindeterminate thing. 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 set pieces of land, sustainable over the longterm. I will explain this quickly, it is complicated. It involves replacing fallowed land, land out of production, replacing it with improved pasture. Pasture grasses, some of which were luminous. They were used for human and animal consumption, and grain and other marketable crops. And then pasture. The idea is that youre devoting a substantial part of your form to growing things the animals are going to eat. That animal digestive process will produce a really highquality maneuver, especially if youre using turnips. Farmers became very careful stewards of this manure, dung, as they called it. It allowed them, effectively, to within the bounds of a permanent, settled farm, raised efficient soil fertility as livestock manure to keep those farms producing indefinitely. They would move pastors to farmland to clover, and rotated through the farm, so the nitrogenfixing of the clover would be used for grain farming later on. This was a very effective system, called convertible husbandry. It managed to retain soil fertility really effectively. But it was incredibly laborintensive. It meant that only a small portion of one plant at any given time could produce crops for market. For those reasons there is actually a reform in the American South of that tried to get southern farmers and planters to raise more livestock and improve their pastors, and to produce highquality manure in a way that would allow them to settle in place, and not be constantly engaging in shifting. It did not work, because they were more interested in using fresh land to produce big crops of tobacco and cotton and maximize their capacity to market these crops. Nonetheless, this was a really important, and pretty powerful way, of raising soil fertility in a closed system. This became the best model of the western world for a closed system for fertility maintenance. Now we will look at how the system gets cracked open. Before doing that, i want to take a quick digression, and that is what happens to fertility management as people urbanized more and more. As more and more people are concentrated in urban areas, urban areas themselves become places that have a lot of organic nutrients that need recycling. That happens in a variety of ways. One, this might be from Great Britain, a figure known as the rag and bone man, they would go around to household and collect any rags that people might have, or bones, as a result of cooking or slaughtering livestock. Do you know what the rags were used for . Rags were the critical resource for papermaking in the 19th century. Papermaking relied upon rag recycling, but the bones were used for fertilizer. These folks would aggregate huge collections of rags and bones. This is a photograph from baltimore, a figure called the nightsoil man. He would go around and collect human waste. This was before there was indoor plumbing, so all of these wastes were collected in privies. It was perhaps not surprisingly, that this is an africanamerican worker. This worker would collect the wastes and take them to the countryside. I will show you that in a minute. Do you know what that is . This is a street scene in lower manhattan. This is horse manure, one of the greatest sources of fertility. And all of these things, nightsoil, bones, horse manure, would be brought out into the immediate hinterlands, and be dumped on the farmlands. Places like long island, brooklyn, queens, those were agricultural hinterlands in new yorks early history. They would produce a lot of crops for urban consumption. And they would get the urban waste recycled back to their land. Not a metabolic rift. But lets move in that direction. One last thing. Anyone know what this is a picture of . American bison. Prof. Sutter yes. These are bison bones. People hunted bisons on the american planes almost to extinction. When the bison were all but gone, commercially extinct, the next industry that hit the great plains was an industry to collect bones, which were then ground up into fertilizer. The question . Is the bison species extinct . Prof. Sutter no, it is not. But it was the subject of intense market hunting. There were so few left, there was a growing Conservation Movement to keep them from going extinct. And now they made a big comeback, although a lot of the bison we see, are crossed with cattle, so they are beefalos. There is a genetic mix there. That gives you a sense of how important bones were to the fertilizer trade. A quick scientific foray. Soil science is also critical to the story. I wont bore you with too many details. Coming into the 19th century, scientists believed in the humus theory of soil fertility, the idea that it was fertile because of the organic matter and manures that breakdown into it. This is a model of soil fertility that i think anyone is spent time doing organic farming would be familiar with. It made a bit of a return. But this man, a german chemist, challenge this and opted instead for a reductive soil chemistry that began to argue that fertile soils relied upon a couple critical nutrients. Nitrogen, potassium, phosphorus. There will be a three number ratio, the ratio of those three elements. He is one of the ones that encourages us to think of fertilizer as more like vitamins then food. The humus theory saw soil as something that needed to be fed. But no, it needed in fusions of these chemical, mineral elements. Nitrogen would be the trickiest one. But as luck would have it, just as liebig was writing his major treatise on the subject in 1840, and industry was beginning to capitalize on a remarkable new sort of concentrated, mineable, nitrogen, that came from an unlikely, remote place. These islands called the Chincha Islands. Anyone know where these islands are . I would like to ask where these islands are located . [laughter] prof. Sutter anyone know . Theyre located off the coast of peru. Prof. Sutter i will show you a map later. It is a very small island, three of them granite, off the coast of southwest peru. Best known as hosts for massive colonies of sea birds, cormorants, pelicans, who would come to these islands, and had been for hundreds of not thousands of years, urinating and defecating on these islands in huge numbers. I have to give you a sense of the magnitude of this because it is actually quite staggering. In some places, and we will see some pictures, people who came to mine these deposits found them to be about 150 feet deep in some places. How could this be . A couple things important about the ecology of these islands, there was the humboldt current that brought nutrients out of the deep sea water and up to the surface, which fed small fish, in this case, anchovies. Huge schools of anchovies around there which allowed the sea birds to feed without abandon on them. And they process this fish fertilizer throughout their digestive tract. The islands also exist in a rain shadow from the andean mountains. They get about one inch of rain fall a year. Why is that important . No rain shadow means there was no chance to wash it away to get harvested. Prof. Sutter in this case, the lack of rainfall effectively means there is no washing away or leaching of this. In most other places, bird guano wouldve been washed away or leached away. These are almost pure, geological deposits of bird crap. They were used by peruvian native people for hundreds of not thousands of years. The great question then humboldt asked, when he made note of these deposits and took peruvian quando back to him with europe where he had chemists tested and found it was incredibly rich in nitrogen. The first deposit to the United States, by order of the editor of the american farmer, in 1824, and within decades, as others confirmed guanos fertilizing power, and International Trade was developed in peruvian guano. A hugely important thing. Sorry, i am a little behind there, there is my slide. As always, i will post these, so if you do not get a chance to jot these down now, they will be here. Here are early illustrations of these islands. These are, effectively, guano deposits. If you dont believe the etching, there is another one. I will show you some photographs in a minute. Alexander von humboldt, brought it back. They are light and easy to transport. So unlike manure or nightsoil, it comes in a light, easy to transport package. Another part of the story that is important to understand, to mine these guano deposits would be incredibly awful work. Have any of you ever cleaned out a chicken coop . Magnify that about 100 annual get an idea. This guano was incredibly acrid and dusty and get into peoples lungs and make them sick. It was not work anyone wanted to do. Not surprisingly, the earliest guano farmers were slaves. Peru outlawed slavery in the 1850s, and it was increasingly fed by a trade in chinese labor. Some of it coming from the fujian coast. About 100,000 laborers from china, semifree labor was brought to peru. Many of them ended in the Chincha Islands where they had to work off the cost of their transport, mining guano. It was awful work, they got paid very little. It was defeated the fertility revolution in the developed world. It is also a story about the decline of slavery and the rise of other types of global labor and migration. Suicide was also a really major problem, particularly among the chinese workers, who often kill themselves because the work was so awful. Heres a look at on