The dirt on civilization ...
or Civilization on the dirt ...
There is a direct correlation between how a civilization treats its land, that is, its soil, and how long it prospers and endures. “A civilization can persist only as long as it retains enough productive soil to feed its people.” David R. Montgomery, Dirt: The Erosion of Civilization (University of California Press, 2012) 236.
How we treat our soil is a function of historical (measured in both geologic time and human time), physical, cultural, social, economic, technological, philosophical, political, and theological factors. Despite the multifaceted variation of societies, that is, civilizations, around the world, there is an evident common cycle of growth and prosperity followed by decline. In highly simplified terms, fertile soil leads to agricultural abundance that leads to population growth. As the population grows, marginal soils are necessarily increasing used for agriculture to feed the population. There comes a point at which the soil becomes exhausted and unable to produce sufficient food to feed the population. Lack of food leads to population contraction. As the population shrinks, the demands on the soil decrease which, sometimes, can allow the soil time to rejuvenate. Boom to bust … the pivotal question being the time horizons. It takes millennia to build soil, but only centuries and sometime just decades to exhaust it.
Start with the Garden of Eden. How’s your Hebrew? “Adam” is derived from adama, which means earth or soil. “Eve” is a translation of hava, which is Hebrew for living. “Life comes from the soil” is perhaps the message of creation. Not Hebrew literate, how about Latin? The Latin word for “human” is derived from humus, Latin for “living soil.” The Romans gave us “Mother Earth,” mater terra.
When and how did agriculture begin? Going back to the time of the glaciers, one of the earliest manifestations of man, homo erectus, survived by following and culling herds of large animals; no permanent or semi-permanent settlements. What changed that caused people to start to settle and become farmers, especially since agriculture was more difficult and time-consuming than hunting? There are lots of theories about why this transition occurred. Whatever the reasons, agriculture developed independently in Mesopotamia, northern China, and Mesoamerica at about the same time.
The slopes of the Zagros Mountains between Iraq and Iran were the first sites of semiagricultural people, about 11,000 to 9,000 BC. Game hunting was supplemented by gathering wild cereals and legumes. However, by 7,500 BC herding and cultivation replaced hunting and gathering in these small twenty-five household villages. The archaeological remains of Abu Hureyra in the headwaters of the Euphrates River in modern Syria show the earliest evidence of systematic agriculture, cultivation of grains. See, photo below.
Then glacial cooling reappeared, the region dried out and food became scarce. Having formerly been nomads, why not just pick up and move? Abu Hureya occupied one of the most agricultural favorable areas in the region, rich soils and ample water. However, it had become, relatively speaking, surrounded by other villages. Each village required a certain amount of arable land area to grow the food to support itself. Thus, there was no place to go; Abu Hureya was hemmed in. The climate shift led to changes in the varieties of crops that could be grown; wild varieties of rye and wheat and drought-resistant legumes like lentils dominated.
China’s “Abu Hureya” was situated along the Yangtse River near Diaotonghuan where wild rice was domesticated.
As the post-glacial climate improved, cultures that adapted to growing grains clearly had an advantage. Human settlements grew beyond those that could be supported simply by hunting and gathering. But then they too faced a limit; how many people could be supported on the available arable land? At what point did the village have to start using less favorable land to feed its growing population? When did farm animals enter the picture? Sheep were domesticated around 8,000 BC; goats at about the same time. Cattle appear about 6,000 BC in Greece and the Balkans, and rapidly spread. The merger of domesticated animal husbandry and farming increased productivity and fostered explosive growth in populations. Then technology came into play; the ox-drawn plow revolutionized civilization and inexorably changed the face of the earth.
Early farmers relied on rainfall. However, increasing numbers of people demanded more agricultural productivity, which increasingly necessitated use of more marginal land and more reliable access to water, which in turn led to irrigation. Canals to feed the crop lands required technical expertise and organization; organization led to [you know what’s coming …] government and bureaucracy. The relatively common culture in Mesopotamia saw a religious elite overseeing food production and distribution (didn’t Hollywood make a bunch of movies about this?).
Arable land, higher yield crop varieties, the technology of the plow, and irrigation, life is good; what could go wrong? For starters, groundwater in semiarid regions usually contains significant dissolved salts. As crops are watered, some of the groundwater is lost to evaporation leaving the salt behind. Left unchecked, sufficient salt will builds up and poisons the plants. A palliative is to leave fields fallow for a period of time. In Mesopotamia the demands on agriculture from an increasing population fueled demands for more irrigation and eliminated fallow times. Eventually, the increasing soil salinization forestalled increases in agricultural productivity, which in turn led to an inability to feed the growing population.
Another problem is keeping irrigation channels from silting, which required manpower and technical skill. Conquered peoples were used to pull mud from ditches, which bought some time. Ultimately, however, the number and extent of fields that had to be watered to feed the growing population could not be sustained and agriculture was abandoned.
Some geophysical and geographically advantageous areas sustained high agriculture productivity over extended periods, for example, the Nile floodplain in Egypt and the alluvial plains of the Yellow River in China. Agricultural productivity aligned with annual flooding that brought fresh silt and abundant water. But where did the silt come from? Forests and grasslands do not release silt; the soil is bound. As the populations grew more marginal land was converted to agriculture, often upslope land. As the increasingly higher slopes were stripped of natural plant growth and tilled, they became susceptible to erosion; the source of the silt, the topsoil.
So what happened when these civilizations ran out of arable land sufficient to support their growing populations? First, they looked to other lands and other peoples. The Romans, for example, shipped grain from Egypt and North Africa to Ostia, the closest port to Rome. As those lands degraded from over use, new sources of agriculture had to be found. Rome conquered Carthage in part to secure its fields.
The Romans knew about crop rotation, manure, and animal husbandry. Yet, the Roman Empire declined and disappeared. Soil erosion progressively degraded agricultural productivity from central Italy as well as provinces of the Roman Empire such as Libya, Algeria and Tunisia. Only Egypt was excepted because of the Nile. Roman philosophers knew and preached that the life of the Empire depended upon the life of the soil, which was dying.
The same historical story has been repeated worldwide … what about today?
We talk about the expanse of the globe, the earth. But how much of our massive “little” planet is soil, dirt that produces food? Soil scientists divide the layers of soil into what are called “horizons;” the term “topsoil” is the A Horizon of soil just beneath the organic debris on the surface.
Even though the Earth is ellipsoid, it is typically characterized oval with a radius of 3,959 miles (6,371 km). Of the radius, how much is soil, and specifically topsoil? At the opening of the Great Plains to settlement, topsoil was estimated to be 6 feet or more. Six feet is approximately 1/3,500,000th of the radius of the Earth, or 0.000029%. Topsoil in some parts of the United States today is 3 inches, about 1/84,000,000th or 0.0000012%. Most soil profiles in the US are 1 to 3 feet thick. This life-giving skin on the planet is relatively thinner than the skin on your arm relative to your body.
The US national average soil erosion rate for sheet, rill, and gully erosion is 7.6 tons per acre per year (TAY). A ton of topsoil is difficult to imagine; converting 7.6 tons to pounds equals 15,200 pounds of topsoil lost per acre per year.
A rough calculation of current rates of soil degradation suggests we have about 60 years of topsoil left in the US. Some 40% of soil used for agriculture around the world is classed as either degraded or seriously degraded – the latter means that 70% of the topsoil, the layer allowing plants to grow, is gone.
https://teacherscollegesj.org/how-much-topsoil-has-been-lost-in-the-us/
The quantity of soil eroded is determined by multiple factors; including weather (wind and rain), the surface of the soil (including the steepness on slope the soil is on), and the cover on the soil surface (i.e., plants or trees). Soil erodes and then replenishes naturally at a rate of only an inch or two per several hundred years. The estimate is that we are now losing about 1 percent of our topsoil every year to erosion, most of this caused by agriculture.
Montgomery, David R., "Soil Erosion and Agricultural Sustainability," Proc. Nat. Acad. Sci. (USA) 104, 133268 (2007).
The United States is losing soil at a rate 10 times faster than the soil replenishment rate while China and India are losing soil 30 to 40 times faster.
S. Lang, "'Slow, Insidious’ Soil Erosion Threatens Human Health and Welfare as Well as the Environment, Cornell Study Asserts,” Cornell Chronicle, March 20, 2006, citing Pimentel, D., “Soil Erosion: A Food and Environmental Threat,” Environ Dev Sustain 8, 119–137 (2006). https://doi.org/10.1007/s10668-005-1262-8.
Soil erosion is a natural process, but it has been vastly and needlessly accelerated by unsustainable agriculture practices in many regions across the United States and globally,” said Marcia DeLonge, author of the study and Food & Environment research director and senior scientist at UCS [Union of Concerned Scientists]. “Healthy living soil is the foundation of our food system and as important to our well-being as clean air and water. It reduces erosion, promotes healthy crops and holds more water, making farmers and nearby communities less vulnerable to floods and droughts.”
Common farming methods strip soil of its nutrients and protective cover, making it vulnerable to erosion. When wind and water erosion deplete soil faster than it forms, the topsoil farmers rely on begins to disappear. Healthy living soil is soil filled with beneficial insects, fungi and microbes that recycle leaves and other material into organic matter and nutrients. It also serves as a natural carbon store to mitigate climate change. …
“Erosion is not just about degrading farmland, it also is about soil and the excess fertilizer and other pollutants it takes with it running off into places where we don’t want it,” said Karen Perry Stillerman, co-author of the study and senior analyst at UCS. “We see this pollution from erosion and runoff everywhere from drinking water sources in Iowa, where it threatens public health, to many miles down the Mississippi River in the Gulf of Mexico, where it harms local fishing communities. Soil loss is so bad now, it’s painful to imagine the situation getting even worse.”
More sustainable farming practices include planting cover crops between cash crops, growing deep-rooted perennials, using conservation tillage or no-till farming, rotating diverse crops and better management of grazing lands, according to UCS. Such practices keep soil in place and build its ability to drain and hold water, increasing farmers’ resilience.
Delonge, Marcia and Karen Perry Stillerman, “Eroding the Future: How Soil Loss Threatens Farming and Our Food Supply,” Union of Concerned Scientists, December 16, 2020. (https://www.ucsusa.org/sites/default/files/2021-02/eroding-the-future-dec-2020.pdf)
Now for the political theater. A top United Nations official claims there is a finite time period before the world runs out of topsoil to support agriculture, triggering a “scientific” response.
Generating three centimeters of top soil takes 1,000 years, and if current rates of degradation continue all of the world's top soil could be gone within 60 years, a senior UN official said on Friday. About a third of the world's soil has already been degraded, Maria-Helena Semedo of the Food and Agriculture Organization (FAO) told a forum marking World Soil Day. https://www.businessinsider.com/r-only-60-years-of-farming-left-if-soil-degradation-continues-2014-12?op=1 (December 8, 2014)
»Fortunately, running out of soil for food agriculture will not be a concern because according to the noted climatologist Rep. Alexandria Ocasio-Cortez (D-N.Y.) the world will end in 12 years.
Claims that the world may only have 60 harvests left because of poor soil management are “overblown” and “nonsensical”, according to new research from Oxford University. …
Environmental campaigners have often quoted the “only 60 harvests left” claim to attack modern farming techniques, including the use of chemical fertilisers [remember it is a Brit talking] and pesticides, as well as deforestation and global warning. … Additional comments by the then Defra secretary Michael Gove in 2017 that farmers “drench” their soils with chemicals and intensive agriculture meant the UK was 30-40 years away from the “eradication of soil fertility”, fueled the claims further. …
Hannah Ritchie, a senior researcher at Oxford University and head of research at the science website Our World in Data, said the team investigated the claims that there are only “30/60/100” harvests left as part of the first global assessment of soil lifespans. Dr. Ritchie said these claims often hit the headlines, but she concluded they were a “myth” and there was “no scientific basis” to them.
https://www.fwi.co.uk/news/only-60-years-of-harvests-left-claim-is-a-myth-says-study
What is clear is modern industrial agriculture; tillage and other practices, and application of synthetic fertilizers, herbicides, pesticides, contribute to soil erosion and soil exhaustion. While the United States has become the breadbasket for the world, how long can it continue to do so? Industrial agriculture is practiced on 95% of agricultural land in the US; 95% of the agricultural land in the US is undergoing continuing loss of topsoil. When will there be no more topsoil on this land? What does the continuing loss of topsoil in the US mean for the US as a civilization?
Is there no hope? It has been demonstrated that regenerative agricultural practices: no till, keeping the soil covered with plants at all times, crop diversity, having living plant roots in the soil year-round, organic farming (no synthetic fertilizer, herbicide or pesticide) and integrating livestock, increases top soil depth and biodiversity. The soil better retains water and reduces runoff, consequently there is less water pollution from synthetic fertilizers, herbicides and pesticides; groundwater is recharged. Regenerative agriculture maintains crop yields and increases crop resilience, and increases the soil’s capacity to capture carbon, which contributes to the reversal of global warming. It reduces demand for fossil fuels, the fossil fuels need to manufacture the synthetic fertilizers, herbicides and pesticides; the fossil fuels needed for distribution and application. Regenerative agriculture can accomplish something industrialized agriculture cannot, it can feed the world.
Only 5 percent of the US agricultural land is farmed using regenerative practices.
