Nature, Science, and a Great Misunderstanding

by Cass C

As fate promises, there is a common future for all existing beings: to end up as a corpse, rotting into the dirt. A morbid concept, perhaps, but it’s something that I have gained an appreciation for, as a soil scientist. Despite the terrestrial nature of soil science, the words of Carl Sagan tend to haunt the brain. 

Our Sun is a second- or third-generation star. All of the rocky and metallic material we stand on, the iron in our blood, the calcium in our teeth, the carbon in our genes were produced billions of years ago in the interior of a red giant star. We are made of star-stuff.

- Carl Sagan

Of course, it is romantic to think that the elements making up your tangible flesh are the same ones making up the mystic cosmos which captivate the mind on sleepless nights, but before you can be a star, shining down on the infinite universe, you will be any number of other things here on earth. But the first thing that you’ll be, after your short human existence, is certain: soil. To most, soil is far from awe-inspiring, it’s the dirt you walk on, the mud on the tires of your car after a long rain. However, I hope to convince you of its wonder. As one of the most misunderstood aspects of our natural world, soil is a rich, living, natural resource with vital importance to life as we know it. 

Chapter 1 – A Recipe

The creation of a soil, pedogenesis (this name confused me at first, too), starts with regolith—raw, rotted rock, unconsolidated raw minerals that are ready to be freed from their crystalline prisons. Upon exposure to water, which acts as an acid, salts from these minerals are dissolved and clay solids are left behind. A small amount of plant life can begin to establish itself, now having access to nutrients that were previously tied up in the regolith. 

 As plants live and die, organic material begins to find itself in the developing soil in form of dead plant material and animal remains/droppings, making for perfect microbe food. As organic material is eaten by soil microbes, it is broken down into nutrients essential for plant growth (most importantly, plant-available nitrogen), allowing for advancement of plant life. Decomposing soil organic matter (SOM) also serves another purpose to plant growth. Organic carbon, a key component of SOM, is not readily decomposed like other elements, and can instead become a dark brown, sludgy material—aptly named humus.

Humus molecules, which are some of the largest, most complex carbon chains ever examined, are negatively charged. This causes them to hold onto important critical positive-charged nutrients preventing them from washing away. Additionally, humus can hold water in large quantities, an obvious benefit to plant life. All of this is the basic “recipe” for soil, but much like every family has their own potato salad recipe, every soil has their own unique characteristics, depending on its parent material, climate, and topography. Anything that can be considered a soil will host some degree of plant life, but the variable factors, of course, determine how fertile a soil is.

Chapter 2 – A History

One of the reasons for the fundamental misunderstanding of soil is the timescale on which it develops. As the child of two geologists, I have long been subjected to the concept of geologic time being too impossibly long for our human mind to accurately comprehend, to the point where one-million years is a mere blink of an eye. As it turns out, when you are a soil, one-million years is actually quite a long time.

If you are a mineral, the time you spend as a soil is a short phase, in between the more permanent affiliations of being a rock and being a salt dissolved in the ocean. The timescale for a soil typically stretches several thousand to several hundred-thousand years, depending on the environment where it is created. 

This, when observing from a human perspective, puts soil in some strange middle ground of being somewhat regenerable, under nurturing conditions, but not renewable in the sense of solar or geothermal energy (especially under the continuation of current crop production demands and changing climatic conditions). This is precisely why the delicacies of soil health must be remembered, and agricultural practices must critically be evaluated to realize the consequences of the modern agricultural practices.

Chapter 3 – Agricultural Evolution

To understand how agriculture and soil health became so removed from each other, it is necessary to recall some agricultural history. Since the dawn of agriculture, naturally fertile soil has been integral to the development of society. The practice of fertilization using manure started early on, which stimulated microbial activity causing nutrients to cycle more quickly and allowed for the cultivation of more land. 

More recently, crises in soil fertility have begun to arise. As human society advanced and the population grew, so did the demand for accelerating agricultural production. When nutrient regeneration in the soil could no longer keep up with the rate of nutrient depletion from increased cropping, there was a scramble to lay hands on nitrogen-rich guano, the finest fertilizer on the market circa mid-1800s.

 But As the nitrogen-mineralizing soil microbes fell short on production, South American seabirds could not shit rapidly enough to keep up with the global demand for plant-available nitrogen. Thus the guano-war broke out as the world anticipated major food shortages once the last bat cave was scraped dry. In typical American-Imperialist fashion, the Untied States even passed a law—declaring that any island containing guano found by U.S. forces could be claimed as American land. 

Anyway, this guano-rush did not last too long, as a very aptly timed discovery was about to be announced. Nitrogen scarcity was almost instantaneously reversed to nitrogen abundance, when early 20th century German chemists Haber and Bosch invented the Haber-Bosch process, that harnessed atmospheric nitrogen into a biologically available state (ammonia, or NH3). 

Chemical fertilizer quickly became the agricultural standard and was regarded as a truly heroic invention, allowing ag production to hit previously unimaginable levels, moreover, allowing for an explosion of the human population. Indeed, farmers everywhere had a new player on the scene, one that helped to develop the trend of intensifying the treatment of farmland. With this new nitrogen fertilizer, it was no longer a priority to input organic matter into the soil—plants could grow without it.

In the midst of agricultural industrialization, the misunderstanding of soil as a resource was revealing itself in the Great Plains of North America. To me, the Dust Bowl was always one of the most mysterious events in American history, but now the underlying cause is clear: the economic environment which fostered disregard of soil health to a hyperbolic extent. 

Formerly stabilized by the deep roots of native grasses, midwestern topsoil was put under the plow. When topsoil is plowed, it is exposed to air, becoming oxygen enriched. This kickstarts microbial aerobic respiration, and SOM decomposition is expedited. The organic carbon which would otherwise end up as humus is gladly eaten by the oxygen pumped microbes, consequently leaving soil lacking organic material. 

With importance of SOM having been deemed obsolete due to new artificial fertilizer, Great Plains farmers would leave soil to be SOM depleted without a second thought. That is, until drought loomed on the horizon. Remember, if you will, the absorbent property of humus. Without this organic sponge, a the drought that hit ravaged the Great Plains in the 1930s caused soils of the region to become parched. The dried-up soil not only was not hospitable to plant life, it was also left vulnerable to the unrelenting winds of the region. As the gusts raged through, hundreds of millions of tons of topsoil took flight, resulting in the bleakness of dust clouds and poverty that is characteristic of this era. 

The Dust Bowl should never have happened, it was the culmination of an era careless agriculture, forgetting that without healthy soil, agriculture is fragile and artificially propped up by industrial measures. To say that the era of careless agriculture is over, however, is not what I mean to do. One must understand the past to make good in the present, so to speak. In part two of this tale, we will examine where we stand now, what is promoted by the ag market and speculate where we are headed, with the industrial agriculture practices happening today.