Center for Regenerative Agriculture and Resilient Systems

The Earth is a Growing Living Matrix—Not a Bathtub

by Sheryl Karas MA, CRARS staff

earth in starry sky with abundant vegetation and crossed-out bathtub

A recent CRARS guest blog post by Tom Newmark(opens in new window), Chairman of The Carbon Underground and member of the CRARS Leadership Council, pointed out the danger in perpetuating the notion that the earth has finite value as a carbon sink (a reservoir for storing legacy CO2 from the atmosphere). The concern is that because of the recent practice of comparing the earth to a ceramic or stainless steel sink or bathtub that can only hold so much carbon, that the true value in regenerative agriculture as both a long term and short term climate change solution is being dismissed. But the earth is not an inert bathtub. The earth is a living matrix that grows soil when the conditions are right to do so—the carbon sink capacity is expandable. 

It is likely true that humankind will benefit most by utilizing as many solutions to the climate crisis(opens in new window) that have been identified as possible. Time is too short to waste on anything else. However, we do know that how we do agriculture is a significant contributor to climate change(opens in new window), and even if you don’t believe in that, soil degradation and erosion alone is a serious threat to the world’s food supply.  

According to a study by the European Commission Joint Research Centre in 2017(opens in new window), we are losing almost 36 billion tons of soil a year due to water and wind erosion, deforestation, and modern farming practices.  The U.N. has been sounding the alarm since 2015, saying at that time that 1/3 of the earth’s soil had already been degraded and that if then current rates of degradation continued, all of the world's top soil could be gone within 60 years(opens in new window)

That is frightening news, especially when generally accepted knowledge is that it takes hundreds, if not thousands, of years for topsoil to be formed naturally through the weathering of rocks combining with organic material from decaying plants and animals. In fact, the need to grow food despite soil degradation is one of the main reasons why tillage and synthetic fertilizers and pesticides are used so widely in modern agriculture. But today we know that these practices when used exclusively can actually increase the problem over time—forcing farmers to use increasingly more chemicals for similar results—because this way of farming interrupts the natural processes nature uses to feed plants via the symbiotic relationship between photosynthesis and the microbiology in the soil. Furthermore, unless conservation measures like crop rotation and cover crops are employed, the soil holds less water every year, washes away in heavy rainfall, and becomes increasingly less resilient in the face of severe weather events. On the other hand, there is growing evidence that by working with these natural processes instead of against them that not only can badly degraded cropland become more viable over time, new topsoil can be actually be regenerated at surprising fast rates, which is exactly what Tom Newmark was talking about. 

Necessity is the Mother of Invention

Roland Bunch, PhD(opens in new window) is one of the most well-respected leaders in regenerative land management, both in terms of food security and for addressing ecological degradation and climate disruption. As a consultant in sustainable agricultural development for over 40 NGOs and governments in 50 nations, Bunch’s work takes him to some of the most poverty-stricken areas in the world where, in some cases, the land has become so degraded that adding fertilizer is no longer a cost-effective option. Small shareholder farmers in Africa, for example, frequently give up the practice of letting land lie fallow to recover because they can’t afford to own enough property to do that and still provide enough food or income for their families. This is also one of the regions already being hard hit by climate change-related extremes in weather, so the soil they do have tends to erode and wash away when heavy rainstorms come after long periods of drought. The job Bunch has taken on is how to help people in these regions grow food despite the considerable challenges. 

The key, Bunch says, is the use of several of the basic practices of Regenerative Agriculture, in particular the use of zero or low tillage, intercropping, green manure, and cover crops. He teaches people to grow a mix of preferably edible cover and secondary cash crops (mostly legumes) which are cut down after harvest and left to lie in place. This provides cover that protects the soil from the elements and, as the plants break down, releases important nutrients like nitrogen back into the soil. Bunch says that within one to two years he has seen farmers, for example, in sub-Saharan Africa, be able to grow food at approximately the national average of those using more conventional tools of agriculture in that region. Within four to six years, they can be producing two or three times the national averages, with greater net profits and more food for their families and communities.  

But additionally, in regards to climate change, Bunch says that smallholder farmers are building up their topsoil with these green manure cover crops and nothing else added at the rate of about an inch every two years(opens in new window). “They say it takes 100 years to create an inch of topsoil. But that’s starting out with rocks and letting nature do it. We can do a little better than that. In fact, we can do a whole lot better than that. We can multiply that process by 50 times, making a half inch of topsoil in a year—topsoil that is rich in soil organic carbon that came from atmospheric CO2.” Bunch estimates that the average green manure/cover crop system used by the farmers he works with sequesters about six tons a hectare of soil carbon per year.  

Of course, one point typically brought up is “Well, that works in the tropics. What about in other parts of the world?” Roland Bunch suggests you talk to Gabe Brown of North Dakota about that. 

From Dirt to Soil 

Gabe Brown came across regenerative agriculture when he and his family were in danger of losing the 1,760-acre family farm they had inherited and were attempting to operate using conventional modern methods as was previously done. But four years in a row of freak storms led to crop failures and the death of many of his cattle. He had testing done on his land and discovered that despite tilling and using fertilizers and pesticides diligently as he had been taught, the soil was badly depleted. He almost gave up in despair but after letting the property sit uncultivated for awhile so he could explore his options, he tested again and found that—without having done anything—his soil was starting to recover! 

Step by step he went down a new trail, adding one regenerative or Holistic Management practice after another, and each choice he made resulted in lower input costs, improved soil health, and eventually paid off in higher yields as well. Today, 20 years later, Brown has a highly successful 5000 acre ranch with crop yields 20-25 percent higher than the average yields in his county. His soil organic matter increased from 1.9 in 1991 to 6.1% and that has increased its water-infiltration rates tremendously. He was seeing rates of 1/2 inch per hour in 1991. Today it is 8 inches per hour. He also has done in-depth testing of his soil’s carbon-retention rates. His soils have 96 tons of carbon per acre in the top 48 inches. 10 to 30 tons of stored carbon is what is typical on conventionally farmed soils in the same region. 

That turned Brown into a proselytizer for soil health. In his book  Dirt to Soil: One Family’s Journey into Regenerative Agriculture(opens in new window) he tells his story and shares how to do it (and why) with others.  

Yes, But Show Me the Science

Christine Jones PhD  has done an excellent job of explaining the mechanisms of topsoil creation with numerous scientific references to back up her claims. In her article “ How to Build New Topsoil(opens in new window)” she says that several centimeters of topsoil can be formed per year if the conditions are managed correctly. She’s working in Australia where 70% of the soil has become seriously degraded, so the subject of topsoil creation is a matter of deep concern for that nation’s food security. Simply working on conserving the soil that is left is insufficient for the problems at hand. 

In her article Jones emphasizes that soil must be living in order for new topsoil to be created. She’s talking about the biology—mostly micro but also macro (soil invertebrates)—that needs to be nurtured and protected in order to break down plant matter and bind it together with minerals underground. Tillage, fertilizers and pesticides kill the biology. According to Jones (and the researchers she cites in this article), building topsoil requires a combination of keeping it constantly protected with cover crops and decaying plant litter (green manure), the re-introduction of earthworms and microbiology (using inoculants in badly degraded cases), and mild periodic disturbance by livestock who add biologically rich fertilizer from their droppings while integrating it into the soil with their hooves. 

Her article provides a “cookbook” for how to create topsoil that is worth a read. She’s a very enthusiastic proponent of soil regeneration who speaks widely at soil health conferences. Watch her keynote address “ Biological Pathways to Carbon Rich Soil(opens in new window)” to learn more. 

A few of the resources cited in her article: 

Bushby, V. (2002). Soil biology, aggregation and structural decline. Stipa Newsletter, 19: 4-7. 

Edwards, K. and Zierholz, C. (2001). Soil formation and erosion rates. In: Soils: Their Properties and Management. (Eds. P.E.V. Charman and B.W. Murphy) pp. 39-58. Second Edition. Oxford University Press. 

Hill, S. B. (2002). 'Redesign' for soil, habitat and biodiversity conservation: Lessons from Ecological Agriculture and Social Ecology'. Proceedings 'Sustaining Our Future: through Healthy Soils, Habitats and Biological Diversity' launch of the 'Healthy Soils Campaign'. Nature Conservation Council of NSW, Sydney, 6 April, 2002. 

Jones, C.E. (2000). Grazing management for healthy soils. Stipa Inaugural National Grasslands Conference 'Better Pastures Naturally', Mudgee, NSW, pp. 68-75. 

Jordon, C.F. (1998).  Working with Nature: Resource Management for Sustainability. Harwood Academic. 

Killham, K. (1994).  Soil ecology. Cambridge University Press. 

Martin, G. (2001). Understanding soil building processes. Australian Farm Journal, May 2001, pp. 66-70. 

Soule, J.D. and Piper, J.K. (1992).  Farming in Nature's Image. Island Press. 

Please refer to her article(opens in new window) for the complete list.