Why COMMUNITIES Should Invest in Regenerative Agriculture and the Soil Sponge.

Grow resilience to floods, drought, heat & wildfire. (And no, I'm still not endorsing the financialization of nature: This is about local and regional public economies, not private or global markets.)

Join us for the next international Soil Sponge and Living Climate Workshop starting in early November, 2024. This article is an (updated) overview of the kinds of things we dive into.

© Didi Pershouse, Wiltshire, UK

It is rare to find a single intervention point that can effect tremendous change and create multiple benefits to the systems around us. The “soil sponge,” lowly as it sounds, might just be that perfect center (around which complex systems come together) for effective community investment, because it is the basic infrastructure that makes life on land possible.

When the soil sponge fails on a small scale, a farm or small ecosystem will collapse. When it fails on a large scale, whole regions and societies collapse. Yet when the soil sponge is intact and healthy, multiple beneficial feedback loops wake up and provide benefits. Regions that regenerate the health of their soils can expect:

• fewer floods and wildfires

• less need for irrigation

• better air quality

• cleaner and more abundant water supplies

• more moderate temperatures

• less erosion and silting of dams

• more biodiversity

• less spending on roads and other infrastructure repairs

• and less spending on public health and disaster recovery.

The Earth’s water cycle, carbon cycle, and nutrient cycle all depend on a healthy soil sponge, which is created and maintained by the ongoing work of other species. For that reason, “regenerative” land management—which I define as land management that follows nature’s own principles and works collaboratively with other species to keep the soil sponge healthy and functional — can address most of our biggest challenges these days.

This article will explain what the soil sponge is; how its health affects human and environmental health, resilience to extreme weather events, and local and global economies; and will suggest a number of opportunities for land managers, communities and local governments to help create the conditions for healthy, functional landscapes to grow.

What is the Soil Sponge?

The soil sponge (sometimes referred to as the “soil carbon sponge”) is a term that Walter Jehne and I use to describe the structural and functional integrity of healthy soil. It is a living matrix that soaks up, stores, and filters water; holds landscapes in place; and provides nutrients for an entire food chain, from what would otherwise be bare rock, hardened clay, and desert sands. Though the soil sponge is now severely degraded across much of the globe, it can come back to life and spring back into action as soon as we allow it.

When helping people understand the soil sponge, I demonstrate its structure and function by “raining” onto two very different visual landscapes made of spongy bread versus flour. Consider what happens when you rain water onto bread (as a proxy for healthy soil), versus onto flour (which functions like degraded soil). The bread (soil sponge) will effectively absorb and hold the water without falling apart, whereas the flour (degraded soil) will erode as the water beads up and spills off of it. Likewise, flour blows away when the wind blows, and bread stays intact. Here’s a demonstration from the “Can We Rehydrate California?” speaking tour.

(If you want to know more about that demo, and find other good ways to communicate about this, you can download the Understanding Soil Health and Watershed Function facilitator’s manual for free here.)

The structural and functional integrity of healthy soil is created by soil biology through a myriad of processes. Three primary actions are:

1. Underground life exudes slimes and glues that bind mineral particles together into little bundles called aggregates, starting with bacteria and fungi that feed off of the sugary root exudates from plants. These soil aggregates tend to stick together even in water and wind. This clumping into bundles also opens up pore spaces around the aggregates where air and water can flow, and roots can explore. (Imagine if a crowd of people clumped into small groups hugging each other, there would be more room to walk through the crowd.)

2. Fine roots, root hairs, and fungal hyphae tie these aggregates into a stringy matrix, giving soil its larger structural integrity.

3. Plant roots, worms, ants, beetles, small mammals, snakes, and other creatures tunnel through the structurally sound matrix, creating larger passageways where even more air and water can flow.

This work is mostly invisible to human eyes, so we have generally not noticed or valued it.

In this photo by © Phill Lee of Regenerate Earth, you can see the mineral particles clumped together into aggregates, the fungal hyphae tying those aggregates together, (and a fine root in the lower left) and the incredible amount of open space underground for air and water.

Healthy Soil Soaks up Water

When a landscape soaks up water like a sponge, risk of flooding and drought are both dramatically reduced, as is wildfire risk. Water is also filtered and cleaned — both physically and biologically — as it flows, creating cleaner water in springs, wells, streams, rivers, lakes, and oceans.

A deep soil sponge creates an in-soil reservoir that holds water at the root zone for plants, helping landscapes stay green longer, putting more atmospheric carbon to work building living landscapes through photosynthesis, and cooling the land surface and air through transpiration, shading, and cloud and rain formation.

Plants can stay healthy and green, photosynthesize for longer, and provide more nutrients to the rest of us when growing in a deep soil sponge due to:

• more space for roots to grow

• more water available at the root zone for a longer period of time

• more nutrients available at the root zone through mycorrhizal and bacterial symbionts that help the plant access and sort minerals.

Maybe it is time for us to notice and value the work that our underground companions do.

Degraded Soil Creates Flooding and Drought

Degraded soil has an entirely different structure and therefore functions in a completely different way when in contact with water. It has lost its biological workforce and has reverted back to a mineral substrate of sand, silt, and clay, which are nothing more than broken-down rocks. The mineral particles in degraded soils are un-aggregated and unorganized, because there isn’t enough diverse plant life above ground to feed the workforce below ground that can create the necessary glues and threads to hold the sponge together and maintain open pores.

Like pouring water onto flour, in a degraded landscape rainwater moves sideways across the land — not percolating down into the land — creating flooding and taking topsoil, pollutants, and sometimes roadways and houses along with it as it picks up speed.

When water can’t soak into soil, floods are followed by drought, and droughts are followed by more floods. Flooding and drought are two sides of the same issue, and they carry enormous costs to both public and private sectors: increased need for crop insurance subsidies; FEMA, state, and local cleanup and repair funds; rising property insurance rates for homeowners and businesses; and rising costs of food and water.

In this photo of a rainfall simulator by ©Benton James, Madison County Soil Conservation District, in Tennessee, these five trays of soil are all the same type of soil, but have been managed differently. On the far left, where soil health principles are being followed, all the water soaks in and the water that collects underground is clean and filtered, nothing runs off. On the far right, the soil is tilled, mono-cropped with fertilizer and pesticides, and has no cover crop or plant material to protect the soil. With several inches of simulated rainfall, not a drop soaks in to the soil. It all runs off—creating flash flooding, brown rivers, and taking a lot of soil (and chemicals) with it.

Soil Erosion Affects Water and Air Quality

Because degraded soil has less structural integrity to hold it together when hit by water or wind, it tends to erode, and it ends up in places where we don’t want it. Richard Cruse, Professor of Agronomy at Iowa State and Director of the Iowa Water Center, has calculated that for every pound of corn that is harvested in Iowa, we lose more than a pound of topsoil. For every pound of soy harvested, we lose two to three pounds of topsoil.¹ Eroded soil ends up in rivers and oceans, clogging up dams and public waterworks and endangering nuclear power plant facilities. The dredging of silt that collects behind dams can cost tens of millions of dollars for a single reservoir. It also ends up in the air — a major cause of our rapidly increasing incidence of respiratory illnesses.

An article on the USDA-NRCS website estimates that the total annual cost of erosion from agriculture in the United States is about $44 billion per year. On a global scale, the annual loss of 75 billion tons of soil costs the world about $400 billion per year.

Around the world, we are experiencing the economic, social, and environmental impact of degraded soil that cannot hold or filter water, and that falls apart when in contact with wind and water. The United Nations Convention to Combat Desertification points to desertification and land degradation as a primary cause of regional conflict and forced migration.

Much of this degradation can be mitigated or even reversed with careful planning that draws on nature’s own strategies to help farms, rangeland, backyards, and public lands recover their structure and function. The soil sponge thrives whenever the soil health principles are being followed.

SOIL HEALTH PRINCIPLES

The conditions needed for soil health are clear when we look at natural systems anywhere in the world where the sponge is still healthy and functional. These conditions can be recreated in a farm, ranch, forest, or backyard. “Soil health principles” give guidance as to how to create those conditions. Here is one short version of the principles:

1. Allow the soil sponge to provide its own food and protection by maintaining living roots in the ground as long as possible, and allowing plant matter to accumulate on the surface of the soil year-round.

2. Eliminate tillage (plowing) whenever possible, to maintain the structure and function of the sponge.

3. Plan your management holistically, to create conditions that welcome a diversity of plant, animal, insect and microbial workers into your farm or landscape.

4. Minimize physical, chemical, and biological stresses on the landscape.

You can find more details on the soil health principles here.

Healthy Soil’s Role in the Carbon Cycle

A healthy soil sponge not only provides resilience to flooding, drought, wildfires, food and water insecurity, forced migration, and other climate events, it also affects the climate itself.

Plants take in atmospheric CO2 and (through photosynthesis, using water and solar energy) turn it into complex molecules. Plants use carbon to build their own bodies, to feed soil life, and to feed all other living things (including us when we eat plants or something that ate plants) as part of the carbon and nutrient cycles we depend on.

All living things, therefore, are made of air. To be specific, about half of the dry weight of all living things is carbon from the air. Soil carbon is the accumulation of that carbon in the “living, the dead, and the very dead” underground. Some of that carbon cycles rapidly through digestion and respiration in the living soil food web. Other carbon cycles more slowly if undisturbed, accumulating in various relatively stable forms like peat, humates, glomalin, and even fossil fuels.

During summer months, because of increased photosynthesis, atmospheric CO2 levels drop. This animated map from NASA shows the flux of carbon levels in the atmosphere throughout the year. Notice that CO2 and CO concentrations are much higher during the months when fewer plants are growing and photosynthesizing, and more fires are burning.

During winter months in the Northern Hemisphere, trees lose their leaves, crop land is typically fallow, and plants in many areas have dried up from lack of moisture. Without active photosynthesis, and with (intentional or unintentional) burning of wood, fossil fuels, dry forests and grasslands, levels of CO2 in the atmosphere rise. Levels peak in May, when snow melts and soils are typically plowed, creating a flush of microbial respiration, with not enough photosynthesis happening yet to take up the additional CO2. Soil degradation and deforestation extend those barren conditions and contribute directly to our rising levels of atmospheric CO2.

Regeneration of the soil sponge can restore a healthy carbon cycle in three ways:

1. We can help increase the uptake of atmospheric CO2 through photosynthesis by increasing the:

• land area that supports green growth (by planting cover crops and regenerating forests and grasslands)

• leaf area that captures sunlight (by diversifying the canopy of plants)

• length of the green growing season, especially in semi-arid areas that currently have a long dry period (by restoring the in soil reservoir provided by the soil sponge).

2. We can decrease the oxidation of soil carbon by reducing soil disturbance and degradation.

3. We can decrease the oxidation of plant biomass carbon from wildfires and preventive burns by providing a more constant in-soil reservoir of water for grasslands and forests. Fire and respiration are both forms of photosynthesis in reverse: called oxidation. They both require oxygen, they both release heat (that was once sunlight) and they both produce CO2 by recombining oxygen with carbon.

One caveat: It may take a long time for us to see the results of any of our efforts to decrease atmospheric carbon. The oceans will have to re-equilibrate — and release the extra carbon they have been holding, back into the atmosphere — before atmospheric CO2 levels go down. That may take 100 years or more.

But we have learned that we don’t have to wait for atmospheric carbon levels to go down before we can cool the planet. A healthy soil sponge can help us start cooling the climate right away. Read on!

Cooling via the Water Cycle

Think of the difference between grass and pavement on a hot day — not just on your bare feet, but in the air around you. As plants photosynthesize, they also transpire the water they have soaked up from the sponge. Transpiration dramatically cools the plant leaves and the surrounding air through latent heat fluxes. One study from Turkey showed that the air temperature above green transpiring landscapes compared to bare soil or pavement is typically cooler by a mean difference of 2.3 and 11.7 degrees Celsius, respectively. The additional soil moisture and insulating buffer of air space provided by a healthy soil sponge and the shading from trees and plants affects temperatures as well, by reducing the absorption of heat in the surface, and therefore reducing the amount of heat that is radiated back into the air.

My colleague, the soil microbiologist and climate scientist Walter Jehne reminds us that water, not carbon, is the primary greenhouse gas, and that water is responsible for most of the heating and cooling dynamics of our blue planet. This offers us various strategies for hydrological cooling that we have hardly looked at. For example, Jehne calculates that if we can increase evapotranspiration on farmland and other human-managed spaces, it could be enough to quickly and effectively cool our regions, and even the planet by the amount they have already warmed. But transpiration can occur only when there is adequate soil moisture for plants, and that depends on the in-soil reservoir provided by a healthy sponge.

How quickly can we increase transpiration? As quickly as we can provide the conditions for the soil sponge to flourish and cover bare soils with green growing plants, increase the complexity and density of the canopy of green leaves, and extend the season of green growth.

According to Peter Donovan of the Soil Carbon Coalition, during bare fallow periods, most corn and soy fields in the U.S. are photosynthesizing (and therefore transpiring) about as much as a creosote desert. This absurdity presents an opportunity. If we add cover crops to farms like these, and manage our perennial grazing lands to develop a more robust soil sponge that could keep grasslands green longer during seasonal dry periods, we can make a substantial difference in local and regional temperatures.

Who Will Take Care of our Living Infrastructure?

If land managers and policy-makers thought of the soil sponge as essential infrastructure — the way we think of buildings, bridges, and roads — we would be making very different decisions about its management. We would choose carefully who managed our public and private lands, (and how). Regional and local governments would pay farmers to rebuild functional watersheds. And we would teach everyone how to create appropriate working conditions for the biological workforce (plants, microbes, fungi, insects, etc.) that all of life depends on for abundant food and water, and a livable climate.

By investing in the soil sponge, a community, town, city, or region could:

• Reduce flooding, flood damage, and associated costs

• Reduce wildfires

• Improve drought resilience

• Provide human and natural communities with abundant clean water and reduce the need for irrigation, water treatment plants, bottled water, and desalination plants

• Reduce or eliminate toxic algae blooms

• Increase net profitability of farms by reducing input and irrigation costs

• Reduce silting of dams and reservoirs and the cost of dredging

• Dramatically improve air quality and reduce the incidence of asthma, COPD, and other respiratory illnesses

• Increase soil fertility and the nutrient density of local foods

• Improve the health and resilience of crops, animals, and humans

• Restore habitat for diverse animals and pollinators

What would it take to create the enthusiasm and money to do that in your region? Remember, we create money to pay for wars and pay off big banks when they fail. We can create money to do this as well.

What would it cost to rebuild the sponge in California’s Central Valley, for example, where the vast majority of our fruits, nuts, and vegetables are grown? (And where air quality is some of the worst in the country.) How might we create conditions that enabled the sponge to regrow? I’ve been meeting with farmers, economists, conservation districts, and policy-makers to look at questions like these.

We know how to do this, and we have guidance freely available from natural systems, as well as innovative farms and ranches around the world. We know how to do it not only at a low cost to implement, but in ways that — according to a groundbreaking study by Claire LaCanne and Jonathan Lundgren — improve the net profitability of farms, restore habitat, and reduce pest damage to crops. We have many great examples of land managers who are successfully restoring the soil sponge, soil fertility, and local watershed function through simple but profound changes.

If it is so easy, why hasn’t it already happened? Many farmers are too scared by their rising debt and tiny profit margins to make a change without a safety net of some sort. Half the farms in the United States are losing money, and farming is the profession with the highest rate of suicide in the United States and many other countries. Peer pressure is huge, and it is difficult to break from the herd. Big Ag continues to push conventional problem-solving, or redirect finance and skim all the profits from innovative thinking. Crop insurance programs, and agricultural lending institutions are often too bureaucratic, and under too much pressure from corporate interests to make the necessary changes in their rules.

This is where forward-thinking people and policy-makers come into the picture.

How Can We Invest in a Functional Soil Sponge?

Here are some thoughts, based on conversations with farmers, ranchers, and other innovators across North America:

1. Create lending and insurance options that recognize and reward farmers following the soil health principles rather than punishing them for being unconventional.

2. Invest in independent research that recognizes and measures actual change over time in land function. Choose projects that:

   1. work with real farms and ranches

   2. recognize the value of complexity

   3. teach and creatively implement the soil health principles

   4. don’t depend on funding from “Big Ag.” The independent research at Blue Dasher Farm is a prime example of this.

3. Help create and invest in municipal bonds designed to help regions build resilience to extreme weather events and avoid externality costs by improving soil health and sponge function. These bonds can provide short-term funding to pay farmers to create a functional watershed for the long term.

4. Get your local conservation district or community interested in measuring changes over time using soilhealth.app.

5. Pay farmers directly (or provide reduced rent) for measurable improvements in sponge structure and function. For example: increases in water infiltration rates, water holding capacity, and aggregate stability; and decreases in bulk density.

6. Help secure land for farmers who are following the soil health principles.

7. Offer your land as an innovation hub for young farmers interested in growing the soil sponge.

8. Invest in educational programs that get land managers, students, planners, and policy folks thinking in systems, asking better questions, and down on their hands and knees exploring soil health and watershed function.

A large-scale transition could quickly succeed in many regions, if it were creatively organized and funded (through public service announcements, citizen-led initiatives, farmer-to-farmer mentor networks, state banks, farmer to farmer lending and equipment sharing, and municipal bonds, for example). The Andhra Pradesh Community Managed Natural Farming Initiative in India has shown how quickly this can happen with minimal costs.

It typically takes two to three years for the soil/plant/microbial system (and the farm management) to adjust. After that transition period, increased farm net profitability will likely offset much of the short-term need for assistance and cost-share programs, while long-term savings on externalities in the public and private sector would more than recoup investment costs.

We can improve nearly everything in life by paying attention to the structural integrity and functional capacity of the soil under our feet.

Join us for the next Soil Sponge and Living Climate Workshop starting in early November, 2024.

You can learn more about all of this and more at the Land and Leadership Initiative.

1. Gelder, B., Sklenar, T., James, D., Herzmann, D., Cruse, R. M., Gesch, K., and Laflen, J. (2017) The Daily Erosion Project — Daily Estimates of Water Runoff, Soil Detachment, and Erosion. Earth Surf. Process. Landforms, doi: 10.1002/esp.4286.