-What energy were agricultural empires, like the Romans, using?
-What are some historic responses to peak soil?
-What are the keys to a positive response to living in a future without fossil fuels?
The Ground Beneath Civilizations’ Feet
The key to sustaining human life in most of the civilizations throughout history has rested upon the ability to produce a steady supply of crops from agricultural fields. Crops grow in soil that is made of different size rock particles and mixed with decomposed plant and animal organic matter. Small rock particles, clay, and organic matter function to hold nutrients, such as nitrogen, phosphorus, phosphate, and calcium, and water through ionic bonds. The organic matter, rock particles, and clay act as a recycling mechanism and trade nutrients back and forth with plants as they grow and die back (Figure 1). Without sufficient amounts of nutrients or water crops become difficult to grow.
While sufficient organic matter is made relatively quickly by plants, small rock particles or silt, clay, and soil nutrients are replaced much more slowly. Small rock particles, clay and soil nutrients are created by many different mechanisms. The dominant mechanisms for forming these soil constituents are through periodic geological processes, weathering of on-site parent rock, and water and wind deposition of off-site soils. While geological processes, like glacier movement and large ocean height changes, are important to understanding virgin soil formation, they are events that are neither presently occurring on timescales nor in places to be pertinent to understanding the long-term fates of agricultural civilizations. Weathering of parent rock occurs in a bottom-up manner (figure 2, left). The soil forms as the symbiosis of plant roots and fungi exude acidic compounds to break down parent rock, which forms rock particles, clay, and nutrients. Weathering occurs very quickly in shallow soils and begins to slow as the soil horizon becomes deeper. Soil can also be brought in through water movement and wind from other sites, where soil was previously formed by one of the other two soil forming processes. The final depth of a soil is determined by the equilibrium of soil deposition and the erosion of soil from the site. The rate of soil deposition approximates something to figure 2 right. Virgin soils that are over 2 meters deep can take periods of time close to that of other non-renewable resources to form because soil deposition slows with depth (Table Below).
|Fossil Resource||Time to Form|
|Oil||10 million years +|
|Coal||1 million years +|
|Soil (2m profile)||100,000-1 million years|
|Fossil Aquifers||1,000-100,000 years|
|Peat (2m profile)||1,000-10,000 years|
Agriculture as Prelude to Strip Mining
The main idea of agriculture is to convert land into people and power. A relatively easy way to accomplish this is to use pioneer plants, like pulses, that store large amounts of carbohydrates and quickly uptake nutrients into their seeds. Additionally, the seed heads can be easily stored, transported, and processed to make food where necessary to maintain a civilization. A key innovation in agriculture is the plow. Civilizations from 1000 BC-1000 AD would use a small single headed plow powered by either human or animal labor and double plowed by plowing once in each direction. Plowing serves two functions. The land is cleared of competing species, which allows for cultivated species to gather more sunlight and water. The second function is to disturb the soil such that some of the stable organic matter is exposed and decomposes. When the negatively charged stable organic matter that was holding onto the positively charged nutrients decomposes, the nutrients are released unbound into the soil. The plants are now able to use less energy to overcome the free energy barrier to pump nutrients into roots. The energy not used in nutrient uptake can instead be put into plant growth and seed formation. Used by both the Greek and Egyptian civilizations, the Romans borrowed their agricultural technologies and coupled it with aqueduct systems. The combination of agriculture and high water usage allowed for Rome to pump carbohydrates and nutrients from fields to cities and armies and then into the Mediterranean Sea or Atlantic Ocean in a single direction without choking on their wastes. While plumbing may have be heralded by our elementary and high school history teachers, it is the last insidious step for complete civilization mining of soils.
The Green Revolution as Prelude to Fracking
Today, global civilization uses nearly the same technologies as the Romans, but with a twist. The plow is no longer able to give plants access to free nutrients. The soils have been completely washed of the nutrients plants need to grow. To remedy this situation, the Green Revolution was born. The revolution in the Green Revolution is to dump massive amounts of unbound nutrients into the soils. The plants certainly uptake some of the nutrients, but many go into the ground water and ocean where organisms proliferate and create dead zones. The soil is now a sink for nutrients instead of the source of nutrients. Our food is now a sink for energy instead of a source of energy.
40 Centuries of Comparative Drudgery: A Positive Response
The beauty of the Roman Empire technology at its height was the massive amount of power brought to bare against anyone that dared to question their hegemony. The dark side of the Roman Empire and other agricultural civilizations was that European soil was turned into “the skeleton of a sick man” (Plato) and the Middle East and Northern Africa became deserts. Asian societies were at first engaged in a similar process as the Romans. The Chinese, Japanese, and Korean empires, however, would all prevent complete collapse by stopping empire expansion and creating a large scale economy in human excrement and hence an economy in soil nutrient recycling. The striking aspect of 40 Centuries of Farming is the massive job of having to haul human excrement out of cities and villages everyday and then back to fields where they had to then be applied onto the fields with more intensive labor. These civilizations stopped the one way agricultural carbohydrate and nutrient pump at the cost of having to engage their economies into recycling their wastes on a scale nearly unrivaled in history. Recycling significantly reduces the power of any process. Conventional agriculture cuts off the endogenous recycling of soils and native organisms and gains power. Civilizations use the first 2 meters of fossil soil to gain power and then have the choice of drudgery in recycling and maintaining the last hundred centimeters of renewable soil or oblivion.
Going to the Source: A Positive Response
The mountains are an interesting area in soil formation. The erosion rate is high because of steep slopes and high winds (Figure 3). The Inca Civilization and Seep Holtzer did not run from this, but embraced it. With great erosion also comes great soil formation. Mountains are always weathering and forming soil at a high rate, since the soil profile is shallow. Also the mountains are a large source of nutrients and minerals because of the newly exposed bed rock. Utilizing terraces to catch soil in regions of high soil formation can be very powerful for a civilization. The historical record of the Incan empire’s vast scale and large welfare state is clear evidence to this power.
Bonfils-Fukuoka Farming: A Positive Response
Fukuoka developed a method of rice farming in Japan in response to modern agriculture, best described in The Natural Way of Farming (I think a more enjoyable read than the One Straw Revolution). The important points of his method are that rice is planted onto ground that is constantly covered with other plants and organisms and never tilled with the plow. Constant ground cover prevents soil erosion by wind and water and keeps nutrients cycling in the soil. Further, fungi left intact by not plowing and applying pesticides and herbicides have the ability to amplify the root network of rice to draw nutrients from a larger area of soil. This symbiosis of plant and fungus also works to make the plow unnecessary by releasing nutrients locked in rock. Fukuoka estimates there were enough nutrients left in his soil for 12000 years of farming with his method, while most civilizations struggle to make it 1000 years. Marc Bonfils took Fukuoka’s method and applied it to wheat, rye and barley in France. It is described well in the publication The Harmonious Wheatsmith.
Forest Gardening: A Positive Response
Perennial plant based agriculture has begun to catch on in some circles, but not all perennials are created equal. Trees and grasses make symbiotic relationships with different types of fungi, ectomycorrhiza for trees and arbscular for grasses. Trees with ectomycorrhiza can weather rock and draw nutrients out of base rock 10X faster than grasses with arbscular fungi. The reason is that trees form a closer symbiosis with fungi and share energy in a more intimate way (symbiosis might be a future topic, if I can wrap my head around it in an emergy way). Trees also dissipate energy from rain and wind further from soil and protect it from erosion forces. If we remember from Figure 1 that soil deposition is a function of weathering minus erosion, then trees will build soil faster and be the basis for civilization when fossil fuels are unable to pump nutrients into the soil. It is therefore no coincidence that China, Japan, Korea, Tuscany, European countries of the Middle Ages, Seep Holtzer and Bonfils all used trees in their climax phases. We should start now by utilizing trees in a mid-succession forest stage to provide our “food, fiber, fuel, fodder, fun, and pharmaceuticals” (Dave Jacke).
The Ugly, The Bad, and The Good
The Ugly is that most virgin empire building soils are long gone. They are not recoverable in neither human nor civilization time frames. The Bad is that fossil fuels in all forms are reaching their limits. There won’t be energy to keep the Green Revolution going and feeding 7-9 billion people. The Good is that there are positive responses that don’t include the ability to create large waste based empires, since the fossil fuels and virgin soils are gone. China, Japan, and the Incas around the middle of the second millennium may represent a vision of the future. They were able to build large cities, which are important for maximizing civilization power. They were unfortunately beat out by Europeans using coal and oil and may have in a weird way been ahead of their time.