The book, Thinking Through Soil: Wastewater Agriculture in the Mezquital Valley, by Montserrat Bonvehi Rosich and Seth Denizen, came out last week, published by Harvard University Design Press. It is an enormous study, partly conducted through the Thinking Through Soil studio course at the GSD, Department of Landscape Architecture, and with the help of the SOM Foundation.

The case study, from the Mezquital Valley in Mexico, is a possible wastewater urbanism scenario that researchers grasp through soil, yes, but by singling out a series of characters, from a cow to metformin, who each tell a story of the soil’s horizon, they compose a wider picture of contributing relations to the soil formation, bottom up. By identifying participants, their contingencies and processes, the designers propose future scenarios for a new soil horizon, taking into account complex socio-economic, political, agricultural, ecological, and health issues. The research cross-sects geographical and urban analysis, toxicology studies, cultural studies, diet, ethnocide, technological investments, botanical research, water quality, sewer, drainage, … that are inherently embedded in the soil’s identity. By this, as the authors write, understanding the soil as “inseparable from its unrealized possibilities and potential future”, the emerging soil is “inherently capable of change”.

We spoke with Seth Denizen, coauthor of the book. (Also, check out The Eight Approximation.)

You are researching anthropogenic soil, soil that is post-natural – a product of human activity. Throughout the book, however, while you scratch the immediate surface underneath our feet, you never use the term Anthropocene.

Yes, you’re right, and it’s a conspicuous omission given how well our work is described by that term. For me, the term anthropocene has always had a problem, and I don’t think it’s fixable unfortunately, which is this strange bit at the beginning of the word: the anthropos. I think of the anthropos like a kind of Yeti: rarely seen yet often cited. Let’s call it the abominable cryptid of natural history. Personally, I don’t think it’s useful to keep referring to this hypothetical human, the anthropos, who is so immaculately general that he (and it’s probably a he) has the power to stand in for everyone on planet Earth. Also, from looking at this book, I think you can probably tell why I feel this way. The place we’ve been studying in Central Mexico doesn’t make much sense from the perspective of the anthropos. For example, in the introduction, I tried to make a short list of the most important material processes that affect the soil we are trying to describe to the reader. The list looks like this: volcanism in the Trans-Mexican Volcanic Belt, catalytic converters, horizontal gene transfer, fugitive petroleum coke dust, drug addiction, diabetes, mosquito spray, surfactant foams, a subtropical climate, schizophrenia, the North American Free Trade Agreement, and the root nodules of alfalfa plants. So we could call this an anthropogenic soil if we want, but then we would be giving the anthropos credit for a lot of things he didn’t generate, like the volcanism that gave the soil a high cation exchange capacity, or the microbial life that helps it cycle plant nutrients. And even if we were fine with that, we would still be left in the position of not knowing who or what to blame if the soil’s properties started to change in a way that disappointed us. To put a finer point on it, if I woke up one day with cadmium poisoning, which is excruciating, and someone told me that it was the anthropos that put the cadmium in the soil that my corn crop bioaccumulated, I would have more questions. I would want to know exactly where the cadmium came from and who put it there. I can also imagine that whoever put it there might prefer we reprimand the anthropos, rather than asking these kinds of questions. From this perspective, our choice of terms isn’t just a harmless preference for one kind of jargon over another. There’s a good example of this kind of moment in the book, where we see the ghostly figure of the anthropos at work –a confirmed sighting– and it’s when the mainly European nutritionists arrive to the Mezquital Valley in the 1930s. They find an indigenous group, called the Otomí, living in this very arid valley called the Valle de Mezquital, eating cactus and drinking pulque. Horrified, they tell the Mexican government that these people must be starving and malnourished from surviving entirely on spiney desert plants. They point out that the Otomí don’t have access to the nutritional benefits of dairy products, which they believe are essential for human (read: anthropos) nutrition. So the government starts spending money to introduce dairy production into the Mezquital. They also try to introduce the soybean, which they think is more nutritious than corn (for members of the anthropos). All of these changes then require irrigation, so more money is invested to expand the wastewater canal network. Of course, it turns out that most Otomí people in the Mezquital are lactose intolerant, as their ancestors had no selective pressure to favor the genetic mutation that breaks down lactose, and later nutritional studies confirmed that there was no malnutrition whatsoever in Otomí communities. Their ‘dryland diet’ contained no vitamin or nutrient deficiencies whatsoever, even by the strange standards of European nutritionists, and they weren’t starving, just a bit run down from life in the aftermath of the long mesoamerican genocide. So part of what we are trying to document in the book is the forgotten historical origin of the wastewater system itself, which can actually be located in scientific claims about what is good and not good for the human-in-general we call the anthropos, who in this case looks suspiciously European. Ultimately, I have yet to find a great reason for talking about humans-in-general, and in a very concrete way, this book wouldn’t have needed to be written if it was possible to describe the soil as simply anthropogenic (as a product of the anthropos). Instead, I spent years trying to relentlessly de-generalize the soil by drawing every single material process that shapes this soil’s formation in some specific observable way.

In the back of the book there’s an index of these processes (we call them “soil characters”) which runs to about 45, and this was the short list. Some of these processes pass for human, some pass for non-human, and some transgress this border in ways that embarrass its claim to continuity. For example, in the process of working on this book I was shocked to learn that the plasmids, which share antibiotic resistance genes through horizontal gene transfer in the soil, also share genes that make microbes more resistant to heavy metals. This means that when heavy metals arrive to these soils in Mexico City’s wastewater, they cause a spike in the exchange of antibiotic resistance genes. Think about that. You might be excused for thinking that the last few billion years of evolution were just a trial run to prepare prokaryotes for life in the Mezquital Valley, where heavy metals from Mexico City’s industrial periphery and antibiotics from the wastewater of 22 million people flood-irrigate the soil every week. Of course, the lesson we should learn from this turns out to be different. The antibiotics we pass in our urine were not actually invented by us, and they certainly were not invented by the anthropos. They were invented many millions of years ago by bacteria, who already lived in the soil. Antibiotics would exist with or without Mexico City, and so would the heavy metals, which are produced by volcanos. So not even the antibiotics can pass for authentically anthropogenic, although their concentrations certainly have a lot to do with specific pharmaceutical companies, who we could name, and specific diseases, which have important histories that we could discuss. So, in a way, you could read this book as a kind of elaborate plea for specificity in constructing the map of material relationships that describe our lives and how we got here.

You built the case around the Mezquital Valley’s wicked water cycle – Extracting the groundwater below Mexico City and freshwater from the next valley to run the city, which produces 60 cubic meters of wastewater per second, which acts as a fertilizer dumped onto the agricultural fields in the Mezquital, where the food for the city is produced by the farmers, eaten and dumped right back into the complex (seemingly closed) circuit. This is, in essence, a model for wastewater agriculture that rejects the paradigm of “elsewhere” waste disposal. While this is a specific and complex case, what can we take out from it?

What we need to take from it is a sense that our cities, particularly cities in arid environments, are missing a crucial paradigm of urban design. In the book, we call this paradigm wastewater urbanism. If you don’t love this term, I sympathize, but what we mean by it is simply the set of cultural, political, and technical practices that make it possible to produce fertile soil from urban waste. We think this set of practices will be critical to increasing urban climate resilience, particularly as we find ourselves on the business-as-usual climate curve. Demographers tell us that by 2050, urban water demand will have increased by 80%, and the IPCC assures us that over the same period, climate change will have significantly altered the quantity and timing of surface water in regions that are already experiencing water shortages. If these predictions are correct, this will mean that water conflict between urban and agricultural areas will get a lot worse over the coming decades. So, urban wastewater reuse is a potential solution to these conflicts. Urban areas can return wastewater rich in plant nutrients to agricultural areas in exchange for priority access to that water. However, as we describe in the book in detail, this practice involves significant risks in most urban environments today, where heavy metals, industrial waste, plastics, parasites, and environmentally persistent pharmaceuticals have become ubiquitous byproducts of urbanization. So right now, wastewater urbanism, as we define it, doesn’t actually exist. All we have are end-of-pipe engineering band-aids. For it to exist, we would need to start exploring urban strategies for how to mediate between the specific geo-biological constraints of soil fertility and the image of the good life that animates urban expectations for what the city should feel like, how it should work, and what’s fair. Because re-using urban water is not simply a technical problem that a machine or piece of infrastructure could fix. It requires a collective agreement for how we should allow the constraints and material contingency of soil to affect our lives. This agreement must be transparently negotiated and over time, and it will probably need to be re-negotiated over time. Just as there is no universal food system, soil condition, or form of life, there is no universal wastewater urbanism. Responses to geo-biological conditions will necessarily take different forms in different contexts around the world. However, what all wastewater urbanisms have in common is a commitment to confronting the health implications of our urban waste rather than, as you say, externalizing its consequences. To do this requires a recognition that in the 21st century, it is no longer possible to imagine our lives as autonomous from all forms of toxicity. We think this belief is the very fantasy that underwrites the production of privileged environmental enclaves whose relentless externalization of toxicity is only made possible by unequal power relations, legacies of colonial violence, and information asymmetries. So the book we wrote is an attempt to outline as clearly as possible what the parameters of a future wastewater urbanism would look like in the Mexico City-Mezquital Valley system; what its dangers are, and how its opportunities should inspire us.

What is the connection between neoliberal soil and the territory? Where is the politics agent? Who does the soil belong to?

This is a great question. The whole book is really an examination of this question, of who the soil belongs to, or what it really means to own soil in the Mezquital Valley. But instead of thinking about the soil as a homogenous piece of property that is either owned or not owned by someone, we see the soil as something more like an organism whose growth and development is, like all of us, contingent on processes that are both local and global. In our case, we begin the book by describing a conflict in the Mezquital Valley, where farmers claim that the government is stealing organic matter from the wastewater that irrigates their fields by treating it in a wastewater treatment plant. Without this organic matter, the chemical and physical properties of their soil changes. They own this soil, but the wastewater changes what they own. It makes the soil grow in different ways. It affects the way the soil binds heavy metals, affecting how bioavailable the metals are to plants. It affects the soil’s fertility and microbial community. It changes the soil in many ways. So the government doesn’t own the soil, but by changing the properties of the wastewater, they change the properties of the soil in ways that have significant consequences. Of course, building a wastewater agriculture system in the first place was a massive transformation of the Valley’s soils, and in both cases we can see that what is ultimately at stake is a set of socio-ecological relationships that the soil supports or forecloses. One consequence of irrigating with nutrient-rich wastewater is that farmers don’t need to buy fertilizer. Farming in the region can still be risky, but if you don’t have to go into debt at the beginning of the growing season to farm, you can’t lose your farm to a bank or creditor. So, one of the claims we try to make in the book is that soil contains social relations. If we think of neoliberalism as a social relation, then it’s not hard to imagine what a neoliberal soil would look like. For example, it could look like the kind of soil that is so lifeless that it requires its farmer to go into debt to farm it with fertilizers and pesticides, whose immediate consequence is to maintain that farmer in this condition of dependence. In this context, there is a politics to soil chemistry, and we could even imagine developing a set of empirical soil tests to determine if the soil was neoliberal or not. Can it support autonomous forms of food production? Can it support food crops that are capable of outcompeting early successional non-food plants (weeds) over the course of a growing season? Of course, testing positive for neoliberalism would not be the end of the story. Soils grow and therefore they can change. This means that soil chemistry can be decolonized. The neoliberal conditions we find in soil beneath our feet can be reversed if we choose to reverse them. But right now, we live in a time where our relationship to soil is deeply cynical, where soil is seen as a kind of generic hydroponic media for fertilizer. We see this a lot in California, where farmers in the Central Valley don’t even want “good” soil. What they want is a generic sandy soil that allows farmers to calculate their fertilizer loads precisely and consistently without the fear of salts accumulating in the profile over time. Nothing sticks to sand, so it all just washes away in the next irrigation cycle, without much thought to where the water will come from in a decade or two. It’s not far off to see the Central Valley as a kind of massive open-air hydroponic project, and this could also qualify as a neoliberal soil whose properties have been shaped by the industrialization of farms and farming. Industrialization is always a project to eradicate ecological contingency; industry never wants to depend on anything, because that makes it vulnerable to production slowdowns and uncertainty, and that’s understandable. However, I would argue that whenever this logic is applied to soil, it becomes a kind of death drive. Contrary to the eco-modernists, I don’t believe it’s possible to eliminate our ecological dependance on soil. It’s also a very strange desire to have. Depending on soil for things isn’t so bad, as any gardener knows. It’s our external gut, which is connected in material ways to our bodies, brain function, and to thought itself. Getting rid of this relationship would probably mean getting rid of ourselves, which I suspect is the silent and unarticulated fantasy of every Silicon Valley food solution, from vertical farming to hydroponic tomatoes. Therapists tell us that hyper-independence is a trauma response. Maybe I’ll end here: could we imagine a less traumatized relationship to soil? This is part of what we’re trying to “think through” in this book.