Photo by Jim Richardson ( of archeologists in Brazil studying terra preta (black earth) soil and how it was created by the indians living there.

Returning to our roots in agriculture requires a shift in our thinking

Guest Post By Laura van der Pol, 2020-2021 Sustainability Leadership Fellow and Ph.D. Student in the Department of Soil and Crop Sciences, Graduate Degree Program in Ecology, and Natural Resource Ecology Laboratory

My grandmother was an avid smoker. I dreaded going to her house because the smell of cigarettes was so pungent it burnt my throat and stung my eyes. She was unable to walk, legally blind, and had a file cabinet bursting with medical conditions most of which I couldn’t pronounce at the time, but this meant that when I visited (which was many times a week), I’d be sitting by her bed in the seat of her motorized cart while she smoked.

There are many things I could tell you about my grandmother that are notable – that she one of the first female lawyers in the state of Georgia; that she was one of the first three people in the US to have hip replacement surgery, that she was an exceptional Bonsai gardener. The fact that she smoked, though, never made sense to me. She knew it was bad for her—really bad—and she had so many other health problems already that cigarettes would only exacerbate. Moreover, it made me feel sick; the grossness of the yellow tar coating everything in her house, notwithstanding. Why did she do it?

As a young person, this made no sense to me. Why would someone do something they knew was harmful to themselves and to people they cared about? Maybe this is a question that finds us all at some point in our lives. I find myself asking similar questions as we face the global COVID19 pandemic, the intersectional crises of biodiversity loss, racial and social injustice, and drastically altered biogeochemical cycles causing rapid changes to ecosystems and our climate. And because I study agroecosystems, I find myself asking this same question about how we grow our food.

Scientists have developed a concept of “planetary boundaries” to describe the physical and known capacity for Earth resources and processes to support human life1. You could think of it as nutritional guidelines, but instead of needing to stay within the delicate range of enough but not too much water, protein, iron, calcium, etc – the boundaries are what Earth can provide: how much freshwater, cycling of essential nutrients such nitrogen and phosphorus, survivable rates of extinction and loss of biosphere integrity, etc. Even if we need more water, calories, nutrients, genetic innovation, etc than are available, we cannot simply wish more them into existence.

Estimates of how the different control variables for seven planetary boundaries have changed from 1950 to present. The green shaded polygon represents the safe operating space. Source: Steffen et al. 2015

Of the nine boundaries described, changes to agriculture over the past 100 years are the dominant force pushing us beyond the planetary boundaries that sustain human civilization2. My goal is not to detail the effects our current practices have on the planet (though here’s a primer and a comprehensive essay) any more than I will lay out why smoking is bad for you.

Instead, I attempt to make sense of the fundamental question: why do we grow our food in a way we know is unsustainable? I unpack how we got here, growing food in ways we know undermine our own future, and offer some ideas about the fundamental shift we need to make for civilization to exist for another 10,000 years – or even 100.

Early roots of agriculture

Example of how human appropriation of resources has transformed mass of animals on Earth over time from wild to domesticated.Ref 26

We are fundamentally grain-powered creatures. Humans began consuming calorie-dense grains (e.g. wheat, barley, corn, rice, etc) and tubers (e.g. potato) as early as 100,000 years ago, long before any plants were domesticated. Evidence of intentional cultivation goes back 23,000 years to modern-day Israel where archeologists found people experimented with wild barley, oats, and wheat. What we would consider agriculture, though, began in earnest in multiple locations across the globe between 5,000 to 10,000 years ago3.

Though at first tenuous and labor-intensive, the cultivation and domestication of plants, animals, and ourselves supported higher population densities than our hunter-gatherer groups and necessitated greater expertise and recordkeeping than ever before. Ultimately, agriculture led humans to invent accounting, written language, and increasingly complex systems of organization3, setting the stage for the world we live in today.

Until recently, we were all farmers living integrated lives

Since early society into colonial times in the US, the majority of people were engaged directly in agriculture (more than 9 out of 10). Without fertilizers, power tools, or a mechanistic understanding of how plants grow, people maintained the soil fertility by practicing a variety of ways to return nutrients harvested to the soil and protect soil from erosion. Chief among these strategies were the cultivation of legumes such as lentils, alfalfa, clover, and peas, allowing animals to graze fields after harvest, and adding nutrient-rich materials such as compost, seaweed, and even human waste to fields3.

Legumes appear early in the agricultural record (c. 7,000 years ago) alongside grains such as wheat, and may have been the earliest successful plant domestication4. Until as recently as the 1950s, farmers commonly sustained 25-50% of their farm under a legume pasture or cover crop to regenerate soil fertility despite the relatively low yields of most leguminous plants5.

Successful early agricultural societies were circular: nutrients were recycled among harvested crops, humans and livestock, and the soil. Rotating a diverse array of crops was the best defense against pests, disease, and weeds that could limit production. The most successful of these systems were highly productive, diverse polycultures which accrued organic matter over time, recycled nutrients, and minimized erosion6. A common feature of these systems is their use of legumes to sustain soil health.

What makes legumes so special?

Legumes increase productivity with nitrogen fixation

Legumes are unusual in the plant kingdom in that they create specialized organs called root nodules where they cultivate bacteria (known as diazotrophs) who can pull (“fix”) nitrogen from the atmosphere where it is abundant (atmosphere=78% N2) but otherwise unavailable to other organisms. This allows legumes to access a pool of the often-growth limiting nutrient, and legumes tend to be rich in protein (nitrogen is the key ingredient) compared to grains or other plants.

Amount of protein in a variety of plants. Legumes (beans, soy) have high concentrations of protein.

Since nitrogen is often one of limiting factors to plant growth, increasing availability of nitrogen to plants often boosts their productivity. The entire trajectory of ecosystem development is often shaped by the prevalence of legumes 7–9, as their root growth and eventual decomposition is often a primary way nitrogen enters an ecosystem.

Legumes improve soil health with soil organic matter formation

Soil organic matter is widely recognized as the main component that determines soil health. It does this because organic matter enhances water retention and infiltration and contains essential nutrients (nitrogen, phosphorus) and food (carbon) for the soil microbes who make those nutrients available to plants through decomposition. Soil organic matter is roughly 50% carbon, and that carbon can be in different forms: protected and unprotected. Most natural ecosystems gain soil organic matter over time—forests tend to accumulate a large quantity of unprotected organic matter from the woody plant growth; ecosystems like grasslands have a mixture of protected and unprotected organic material, but much more of it tends to be in the protected, mineral form. As ecosystems gain organic matter, they do so by photosynthesis which removes that carbon from the atmosphere for as long as the organic matter remains as plant material or is transformed via decomposition into soil – which could be days or centuries depending on the soil, climate, management, and form that organic matter is in.  

Though agriculture tends to result in the loss of organic matter over time12, legumes may promote greater organic matter formation than other crops due to their high nitrogen content and ability to stimulate microbial activity in the soil11. Unlike many crops or woody plants, the nitrogen-rich legume tissues are more likely to decompose into the protected, slower cycling organic matter, potentially aiding in longer-term soil carbon storage13,14.

Overview of how particulate (‘unprotected’) and mineral-associated (‘protected’) organic matter form and function. By Jocelyn Lavallee, PhD. Featured in The Conversation

Agrarians no more: the invention that led to our dis-integration

We can all identify with the desire to get more for less, and it is a biological imperative to obtain more energy than you expend in acquiring it. Agriculture’s departure from the integrated cyclical model it had followed for millennia began in the 1840s when early European agronomists such and Justus von Liebig determined that adding nitrogen to crops could increase production. Rather than conceive of ways to enhance nitrogen recycling through cultivation, Liebig and others promoted a reductionist view that relied on importing materials from outside the system.

Early fertilizers were naturally occurring and rapidly depleted deposits of bird guano and nitrogen-rich rocks (caliche) off the coast of South America4. Caliche was also used by Allied forces during World War I to make explosives, and it was Germany’s realization that it could and would be cut off from this resource so vital to weapon-making that prompted the country to invest in research to develop what is arguably the most consequential invention humanity and the Earth has yet known: the Haber-Bosch process.

The development of the Haber-Bosch process has a fascinating and disturbing history (check out Radiolab), but it essentially enabled humans to do the work of legumes in an industrial setting: fix atmospheric nitrogen into the biologically usable form of ammonia. Nitrogen fixation (both biological and industrial) is energy intensive due to the intrinsic molecular properties of N2 gas, but while biological fixation is solar-powered (via photosynthesis), industrial fixation is powered by non-renewable fossil fuels.

Since the 1950s when commercial fertilizers first became widely available, fertilizer application has increased 8-fold15, and fertilizer production accounts for 1% of global energy use4. Here’s a statistic to keep you awake at night: half of people alive today and an estimated 5.5 billion people by 2050 owe their existence Haber-Bosch15,16. While in 1950, at least 50% of the nitrogen in food was from biological fixation, by the 1990s that had decreased to only 20% as synthetic fertilizers replaced legume cultivation.


Commercial availability of synthetic fertilizers rapidly accelerated the shift from circular, solar-based agriculture to linear, fossil fuel based systems, but these practices were institutionalized in the US through the Federal Crop Insurance Program17. The unstable markets of the Great Depression (1933) and the unsustainable practices of frequent (7-8 times per year) tillage coupled with a decade-long drought that became the Dust Bowl (1936) led to many farmers to need disaster assistance and many more to lose their land18. As part of the New Deal under President Franklin Roosevelt, crop insurance was created as a means to support rural economies, ensure national food security, and stabilize food prices.

The program was unpopular at first, and hemorrhaged taxpayer funding until the 1950s when the federal government paid bankers a commission when they issued a loan to a farmer with insured crops17. In this way crop insurance tied new technologies that enhanced production (fertilizer, herbicide, more sophisticated equipment) to the financing needed to acquire these production-enhancing tools and institutionalized what Willard Cochrane termed the “technology treadmill”.

The treadmill begins with farmers adopting technology that increases their production, giving the early-adopters a profitable edge. As more farmers adopt the new technology, however, food supply increases and prices fall, diminishing the profits of everyone involved. To stay viable, farmers are forced to acquire more land and newer technology to ‘stay ahead’17, requiring more financing (loans) to acquire new technology to sustain the high productivity levels needed to repay the substantial loans used to increase productivity in the first place.

Depiction of Cochrane’s simplified technological treadmill by Rachel Carter, Dartmouth College.

This drive towards increasing productivity and higher yields has resulted in food systems that are less diverse and dependent on fossil-fuel energy. High-yielding grains have displaced most of the legume cultivation farmers traditionally relied upon to sustain productivity with only 7% of cropland in a given year planted to legumes (not including soy; compared to 66% for grains).

Unlike smoking, technology in agriculture is not universally bad, just unsustainable

Unlike smoking, the financialization and technological development in agriculture are not unequivocally harmful. Since 1961, the total number of calories produced has increased faster than population growth (global average food production per person 1961: 2189 kcal person-1 day-1, 2017: 2884 kcal person-1 day-1)19. Grain productivity per hectare has increased 2.2-fold, and the proportion of people who are undernourished halved since 1990 (one billion people or 19% to 800 million people or 11% of global population)19.

While increased production has alleviated suffering, it has led to new challenges. As fewer are undernourished, the proportion who are over-nourished (overweight) increased from one-fifth of the population to nearly 40% (1.9 billion). Less land is devoted to nutrient-dense crops such as legumes, fruits, vegetables, barley, oats, and millet making it likely the crops grown cannot supply adequate nutrients for human needs19.

Nor can we blame any single person, industry, or policy for how we got here as we might if examining the nefarious lies told by the tobacco industry that may have contributed to my grandmother’s cigarette addiction (though we may be justified in our blame of fossil fuel industry regarding climate change and proliferation of plastics in ecosystems). The drive to do more with less is a compelling, even biological, motivator for change. In actuality, though, we invest more energy into agriculture now than ever before. Studies of hunter-gatherer societies estimate they obtain 26-69 calories for every one they spend searching for food, a concept called the energy return on investment. Modern agriculture in countries like the US have an average energy return of just 0.25 calories for every one invested. No organism nor civilization can invest four-times the amount of energy it gains to support itself for long. We’ve managed to do so for nearly a century now, but even if we ignore the planetary boundaries we’ve exceeded for climate, nutrient cycling, and biodiversity, the energy return for fossil fuel extraction peaked 50 years ago.

Where do we go from here?

On the one hand, what needs to change is simple: we need to return to the roots of agriculture and embrace circular nutrient economies through crop breeding and legume cultivation, reduce reliance on fossil fuel energy, reduce meat consumption, diversify with crop rotations and animal integration2. Collectively these practices are increasingly falling under the term “regenerative agriculture”.

Of course, the solution for my grandmother seemed simple as well: she simply needed to stop buying cigarettes. We know what to do—we did it for thousands of years. But simply knowing better, even having the ability to choose better, does not often lead to change.

Photo source: General Mills

To help someone recover from an addiction, there must be a desire for change and a social support network to facilitate, guide, and reinforce that change. That is much more difficult to achieve for a disabled, blind elderly woman than changing an item on the grocery store list. The challenge we face with making our primary instrument of civilization sustainable is far more complex. How can we hope to relinquish the same technology and energy resources that have facilitated such immense productivity gains and set us on track to have more than 9.7 billion human mouths in less than 30 years?

“We can not solve our problems with the same level of thinking that created them” ― Albert Einstein

There’s been much hype in the news and in proposed legislation to tackle dual challenges of climate change and soil degradation through what has been termed ‘carbon farming’. These efforts, whether through tax-payer funded programs or large investment companies such as IndigoAg or smaller firms such as NORI, seek to pay farmers to sequester carbon in their fields through improved management (‘regenerative’) practices. The assumption is that many of the barriers to adopting regenerative practices are that they are too costly—requiring different equipment and reduced yields (income)—and this is true. The rate of return of on-farm investment in soil health is negligible (<8%), though societal benefits may be significant20 . In other words, regenerative farming does not make financial sense without additional incentives, and lawmakers, food corporations, and even fossil fuel companies are rushing to provide that financing.

I cannot help but think of this attempt at a solution like paying people to lose weight or to quit smoking. Of course, people who need the money will likely be tempted to change their behavior with a financial incentive. Maybe some would maintain the behavior change on their own with or without the extrinsic motivation—the extra cash is a welcome bonus. But without addressing the underlying circumstances leading a person to choose the behavior in the first place, how long can a financial incentive work to effect behavior change? Psychologists and economists who’ve examined this question typically conclude financial incentives only work over the short term and may even backfire. My grandmother wouldn’t delay smoking a single cigarette when I asked her to, let alone give up smoking for any long-term personal gain.

Ultimately, these financial solutions to agriculture and climate change mitigation seem like tobacco companies offering “healthier” cigarettes or fossil fuel companies hawking “clean coal”. Reducing harm is a good thing, but when our addiction could undo civilization itself, we need more than harm-reduction: we need to change our system for valuing our food and environment.

Shifting our thinking: Returning to our roots

Shifting from a system that incentives highly-mechanized production of a handful of monocultures largely to feed livestock to one that is solar-powered, diverse, and that feeds people will require shifts at many levels of society. Most people in the US, Australia, and Europe will need to eat more plant-based protein and less meat—that change in behavior might be best initiated by ending the many subsidies for corn and ethanol production that may lead the price of grain-fed to livestock in concentrated feedlots to reflect the environmental degradation they impose more accurately. Reduced cropland devoted to feeding cows will free more land in these countries for a greater diversity of crops including legumes, likely to substantially reduce the need for herbicide and pesticide application as well as increase the nutrient availability of food5 and promote increased soil organic matter formation21.

On the policy side, much could be done to improve the effectiveness of tax-payer programs to support investment in soil health and regenerative ag practices such as financing one-time equipment purchases and subsidizing crop insurance premiums for growers incorporating diverse rotations and cover crops. In 2018 less than 1% of USDA funding went to support soil health and carbon sequestration practices. Given an annual discretionary budget of $23 billion (and $140 billion total), there is substantial capacity for greater support through existing programs. Moreover, tax-payer funded crop insurance could be re-designed to require plans for soil health management and support historical farm income rather than rely on yield history of a particular crop, thus fulfilling the main goal of serving a social safety net for farmers without creating the perverse incentives to delay adapting management to our changing climate while placing tax-payers on the hook for crop losses22.

Finally, we need to go beyond the handful of grains we rely upon today and begin to think perennially. Natural ecosystems sustain high levels of productivity without fertilizer; they have tight nutrient cycling and efficient water use, support high biodiversity, and tend to accrue soil organic matter over time23. None are dominated by annual plants, but nor do they they grow dense swaths of things humans like to eat. Finding the balance between the diverse, perennial communities in natural ecosystems and the highly disturbed, annual monocultures we cultivate for food is our best chance for sustainable food systems.

Kernza, a perennial and forage grain bred by The Land Institute (right) compared to annual wheat, showcasing the deep roots of the perennial crop. Feature in Civil Eats article by Cat Wolinski (2016).

Perennial grains such as those being bred over the past four decades at The Land Institute offer a vision of productive and diverse agroecosystems with the benefits of perennial plants to keep soil covered, promote soil organic matter formation, reduce erosion, and sustain high productivity with integrated nitrogen management from legume-grain intercropping rather than synthetic fertilizer24,25.

Ultimately, we need to embrace a world-view that is holistic and collaborative by design and move away from the reductionist, exploitative model we’re in currently. Legumes are eminently practical and innately beneficial to soil and society, yet we’ve nearly eliminated their routine cultivation. Attaining agricultural and cultural sustainability requires us to broaden our view of what we value to include not only ourselves but also the earth systems that sustain us, that have sustained us for millennia, and to design our systems such that the choices that are easiest and most affordable are the ones that support us all.

My grandmother did not live in a world like that. Living in an urban environment designed for cars and people with functional legs, she was increasingly isolated except for visits from her daughter and grandchildren. A simple trip to the hair dresser (her monthly social engagement) could be daunting, seeking a building with a ramp and a navigable sidewalk. I’ve come to appreciate her harmful habits and why they were so difficult to change. I feel hope, too, though. With so many awakening to the intersectional crises looming before us, I believe we are gaining the intrinsic motivation essential to make the shift.


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