Talk Dirty to Me

“OK. There are more living organisms in one tablespoon of soil than there are people living on the earth.”

S oil.  An immense, churning cauldron of living things: earthworms, all kinds of small arachnids, diverse populations of insects and fungi, and thousands (millions?) of bacterial species.  It is the largest sink of global carbon, estimated at over 2.5 trillion tones.  It is the substrate, the foundation, for plants to grow and for ecosystems to stretch to the sky.

It is necessary for human existence.  From building materials to fossil fuels, from water to antibiotics (over 70% of antibiotics currently used today are derived from soil bacteria)¹.  And perhaps most fundamentally, food. We recognize that regions of the world with fertile soils, rich in carbon, have developed economies and stable societies, but those that don’t often are beset with poverty, instability, and a lack of economic development, education, and health. Unfortunately, soil health is frequently ignored.  Soil abuse occurs throughout crop systems in many fundamental, existential ways. Erosion is the most recognized form of abuse. A recent study published in Earth’s Future estimated that since farmers began tilling the U.S. central plains 160 years ago, over 57 billion metric tons of topsoil have been lost² (Figure 1).  Such losses continue even with conservation efforts that began in the 1930s (following the dust bowl) to reduce soil loss. The rate of erosion poses a direct threat to sustainable food production and ecosystem viability³.  Since 1950 there is evidence that one third of the world’s agricultural soil is highly degraded⁴ (GS Gupta, 2019), threatening food security, hunger, social unrest⁵ and more.  Such degradation not only affects food, but our ability to sequester additional carbon, a means to reduce the buildup of greenhouse gas emissions.

Figure 1. Isaac Larsen, a geosciences expert at UMass Amherst, stands near a drop-off that separates native remnant prairie from farmland in Iowa. Researchers found that farmed fields were, on average, more than a foot lower than the native prairie.

Erosion of course, is not the only form of soil abuse.  There are a host of ways and means by which industrial ag can tear down soil health:
Monocropping: growing the same crop on the same piece of land for multiple years, depleting soil nutrients, reducing organic matter and increasing the risk of erosion⁶.

Excessive Synthetic Fertilizers: As important minerals such as nitrogen and phosphor are removed from the soil, addition of synthetic fertilizers, (primarily from fossil fuels) are needed to maintain or increase productivity.  But the addition of these fertilizers can also decrease soil biota, including bacteria and fungi, or favor the development of more pathological strains⁷. Excessive fertilizer application can also result in heavy metal contamination and accumulation of nitrate, which is associated with pollution of ground water⁸.   

Pesticide Residues: While pesticides can break down in soil, others can accumulate.  Their presence can, in turn, affect not just the desired pathogen, but many beneficial soil organisms including nitrogen fixing microbes. 

Farm Waste: Animal operations, particularly CAFOs or Concentrated Animal Feeding Operations are substantial sources of harmful microbes and pharmaceutical residues which can result in antibiotic resistant bacteria in soils. Methicillin resistant Staphylococcus aureus (MRSA) can be spread through CAFOs⁹. CAFO manure can contain more than 150 pathogens with potential to contaminate ground sources of water; CAFOs can also generate significant airborne gases that can impact public health including ammonia, hydrogen sulfide and methane. 

Tillage and Soil Compaction: As farm machinery has gotten heavier, it has led to increasing soils compaction, leading to poor water absorption and poor aeration, with subsequence limitations in root growth in crops and smaller yields. 

The benefits of healthy soil are incalculable. To achieve these sustainable benefits requires maintenance or expansion of soil organisms to protect natural biodiversity; to improve carbon and water retention, to increase organic matter; to provide the first line of defense in maintaining food security.   

Soil can be renewed, but it takes a while. The John Innes Center, an independent research institution focused on plant and microbial science, estimates that it takes 200-400 years to generate 1 cm of new soil—and that’s if you don’t try to grow anything in it¹⁰.  Simply put, modern industrial agriculture is eliminating soil faster than nature is producing it. A change, a fundamental and immediate change in how we treat soil is urgently needed. 

Now imagine the sound of a crystal wind chime….the sound of Rainbows, Unicorns and Sprinkles.  

Biochar.  

Some background.  First, the idea of turning organic matter, food remnants, leaves, waste of any kind (yes, that kind of waste), into a kind of biological charcoal (biochar for short) has been around for a couple of thousand years.  The idea may have originated in the Amazon basin about 2500 years ago as a means to improve soil fertility in a region where, given its tropical nature, soil fertility is inherently poor.  This type of soil, described by Wim Sombroek, a soil scientist at Cornell, was deemed Terra Preta or “dark earth” and was endemic to farming locations within the Amazon basin¹¹.  Indeed, the soil remains highly fertile even today, with little application of synthetic fertilizers.

Figure 2. One meter deep soil profiles between typical infertile tropical Oxisol on the right and Terra Preta on the left¹².

Simply put, biochar, aka, agrichar or black carbon, is a regenerative means to take organic waste and by increasing pressure or by burning under low oxygen levels, produce a substance that is rich in carbon content.  A substance that when added to agricultural soils¹³ can:

Improve Soil Fertility: Soil need beneficial bacteria and fungi, adding biochar can help these microbes flourish. 

Increasing Crop Yields: The porous structure of biochar can attract and maintain nutrients, from nitrogen to phosphorous; and soils with biochar have high nutrient densities. As such, crops grown on such soils have higher yields. 

Increase in Water Retention: Because biochar is porous (the charcoal part of biochar), it can help the soil retain water.  

Mitigation of Soil Pollutants: The large surface area and porous nature of biochar can also be a factor in adsorbing or retaining toxic heavy metals, reducing their transfer into drinking water sources. 

Increasing Pathogen Resistance: More work in this area is needed; but there is evidence to suggest that biochar, by increasing the amount and diversity of soil microorganisms may reduce the chances of any one bacteria or fungi becoming the dominant species, thus reducing the occurrence of pathogens known to be harmful to a given crop.  

Increasing Carbon Sequestration: Biochar, in addition to all its other benefits can also capture carbon and, potentially, store it in a stable form.  When plants decay and are decomposing, they emit CO2, which biochar helps stabilize, allowing it to be retained in the soil for hundreds, or even thousands of years.  

If biochar sounds like the greatest thing since canned beer, there is a reason– its ability to solve and sustain soil health– especially in regard to climate change solutions is becoming more prominent.  Research by Johannes Lehmann at Cornell demonstrated that 12 percent of global greenhouse gas emissions could be negated using biochar produced sustainably from organic waste—waste that by itself would decompose and add additional greenhouse gases (e.g. methane) to the atmosphere¹⁴.  

So why isn’t the pixie dust of biochar being applied to everything, everywhere, all at once?    

Well, not all biochar is the same, it reflects the organic waste from which it is derived, biochar derived from sewage sludge may have a better ability to remove heavy metals from contaminated soils than biochar from wood waste¹⁵.

But the biggest obstacle is cost.  In 2019, the Extension Foundation reported the average price for biochar in the US was $1.29 per pound or $2,580 per ton¹⁶.  Bad enough, but the full benefits of biochar may not be evident in the soil until about 10 tons of biochar is applied on an acre basis.  

Work is ongoing, and prices have fallen slightly. Still, that’s a lot of cheddar.  

Hmm.  What if there was an alternative source of biochar, one that was a couple of hundred dollars a ton? Did I hear Rainbows, Unicorns, and Sprinkles chime?

Wait—-where would this source come from?  Well, it’s a natural source–not too dissimilar to how biochar is formed, but much slower.  Dead plant material accumulated in swamps (low oxygen) subjected to immense heat and pressure.  And with time, the dead plant material transforms into moist, low-carbon peat.

And then to coal.

WHOA!  Coal?   That stuff we aren’t supposed to burn because it adds lots of carbon to the atmosphere?  Are you insane?

But what if it isn’t burned—what if it is buried—but in a different form?  

From the University of Wyoming Newsletter¹⁷, April 7, 2022:  

University of Wyoming soil science researchers are conducting preliminary tests of a coal-derived soil amendment that so far is producing results similar to another popular soil amendment, biochar. The initial phase of the project began in a greenhouse study through the guidance of UW Professor Emeritus Peter Stahl. The greenhouse experiment examined plant growth and soil properties with both biochar and coal char in different soil types.

Pyrolyzed coal or coal char has many physical and chemical properties similar to biochar, a widely used soil amendment, Stahl says. Like biochar, coal char has the potential to enhance the water and nutrient-holding capacity of soil.

It’s no secret that coal prices and demand are declining, and as the need for cleaner fuels intensifies, it is unlikely that coal will remain the predominant fossil fuel.  But it is a resource, a carbon-intensive one.   

One that, at present, is selling for about $200 a ton, less than a tenth the cost of biochar.  

If there is more to learn about biochar, there is an even greater leap of knowledge that must accompany the use of coal, but there is a rainbow, unicorn and sprinkle promise—burying, not burning, coal could offer a cheap, sustainable means to improve the most degraded soils.  Adding, in essence, dead plants and coal char returned to the soil, may be a means to cheaply, and universally improve marginal soils the world over.  Everything, everywhere, all at once.

Maintaining and sustaining soil health will always remain a fundamental means to ensure the quantity and quality of our food supply, increasing our ability to increase carbon sequestration to help mitigate climate change.

Soil abuse needs to be recognized and stopped.  Soil is priceless.  Don’t treat it like dirt.

Dr. Lewis Ziska is an American plant physiologist, academic, and author. He is an Associate Professor in the Environmental Health Sciences at the Mailman School of Public Health at Columbia University. He is also the Climate and Health Certificate Lead and the Health Climate Coordinator for Public Health. His most recent book is Greenhouse Planet by Columbia University Press.

References. Part 2. Down on the Farm. Chapter 1. Talk Dirty to Me.

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¹ Chandra, N. and Kumar, S., 2017. Antibiotics producing soil microorganisms. Antibiotics and Antibiotics Resistance Genes in Soils: Monitoring, Toxicity, Risk Assessment and Management, pp.1-18.

² https://www.umass.edu/news/article/midwestern-us-has-lost-576-billion-metric-tons-soil-due-agricultural-practices

³ Wuepper, D., Borrelli, P. and Finger, R., 2020. Countries and the global rate of soil erosion. Nature sustainability, 3(1), pp.51-55.

⁴ Gupta, G.S., 2019. Land degradation and challenges of food security. Rev. Eur. Stud., 11, p.63.

⁵ https://www.nhm.ac.uk/discover/soil-degradation.html

⁶ Belete, T. and Yadete, E., 2023. Effect of Mono Cropping on Soil Health and Fertility Management for Sustainable Agriculture Practices: A Review. J. Plant Sci, 11, pp.192-197.

⁷ Paungfoo-Lonhienne, C., Yeoh, Y.K., Kasinadhuni, N.R.P., Lonhienne, T.G., Robinson, N., Hugenholtz, P., Ragan, M.A. and Schmidt, S., 2015. Nitrogen fertilizer dose alters fungal communities in sugarcane soil and rhizosphere. Scientific Reports, 5(1), p.8678.

⁸ Abascal, E., Gómez-Coma, L., Ortiz, I. and Ortiz, A., 2022. Global diagnosis of nitrate pollution in groundwater and review of removal technologies. Science of the total environment, 810, p.152233.

⁹ Osadebe, L.U., Hanson, B., Smith, T.C. and Heimer, R., 2013. Prevalence and characteristics of Staphylococcus aureus in Connecticut swine and swine farmers. Zoonoses and public health, 60(3), pp.234-243.

¹⁰ https://www.jic.ac.uk/

¹¹ https://sswm.info/sites/default/files/reference_attachments/SOMBROEK%20et%20al%202002%20Terra%20Preta%20and%20Terra%20Mulata.pdf

¹² Glaser, B., Haumaier, L., Guggenberger, G. and Zech, W., 2001. The’ Terra Preta’ phenomenon: a model for sustainable agriculture in the humid tropics. Naturwissenschaften, 88, pp.37-41.  

¹³ Ding, Y., Liu, Y., Liu, S., Li, Z., Tan, X., Huang, X., Zeng, G., Zhou, L. and Zheng, B., 2016. Biochar to improve soil fertility. A review. Agronomy for sustainable development, 36, pp.1-18.

¹⁴ Lehmann, J., Cowie, A., Masiello, C.A., Kammann, C., Woolf, D., Amonette, J.E., Cayuela, M.L., Camps-Arbestain, M. and Whitman, T., 2021. Biochar in climate change mitigation. Nature Geoscience, 14(12), pp.883-892.

¹⁵ Zhao, J., Shen, X.J., Domene, X., Alcañiz, J.M., Liao, X. and Palet, C., 2019. Comparison of biochars derived from different types of feedstock and their potential for heavy metal removal in multiple-metal solutions. Scientific Reports, 9(1), p.9869.

¹⁶ https://farm-energy.extension.org/biochar-prospects-of-commercialization/

¹⁷ https://www.uwyo.edu/uw/news/2022/04/field-tests-of-coal-derived-soil-amendments-yield-promising-results-for-uw-researchers.html#:~:text=Pyrolyzed%20coal%20or%20coal%20char,nutrient%20holding%20capacity%20of%20soil.