Loss of soil moisture: how to interpret the findings
Hart Hagan
Let’s talk about the underrated and overlooked topic of soil moisture, the latest findings, and how to reverse these disturbing trends
The topic of soil moisture sounds mundane or even gross. But life on land depends on soil moisture. Agricultural productivity depends on soil moisture. The health of the forest depends on soil moisture. Whether your garden thrives or suffers depends largely on soil moisture.
Recently, top scientists reported on the dramatic worldwide decline of soil moisture. Unfortunately, they didn’t know what they were looking at. They told us the facts, without knowing how to interpret those facts.
Sorry for the late notice, but here is a link to today’s free webinar on this topic: The Worldwide Loss of Soil Moisture: Friday, October 17 @ 3:00 PM (Eastern Time)
Issues addressed herein:
Have our soils lost moisture in recent decades?
How much moisture have our soils lost in recent decades?
What elements of our living systems depend on soil moisture?
What can we do to reverse the loss of soil moisture?
What are the Five Principles of Soil Health, and how do they work?
How can we create empty spaces in our soil, such that the soil soaks up rainfall and holds onto it?
Why is it erroneous to blame declines in soil moisture on “climate change”?
Why is it erroneous to blame these trends on “drought”?
How do farmers and gardeners degrade soil health?
How do we degrade soil health in our forests, and what can we do differently?
Think about it … if the soil loses moisture, then the soil organisms die. Water is life. All living things need water, including the all-important soil microorganisms.
Here is a graphical representation (by regenerative farmer Matt Powers) of the organisms that exist and thrive in healthy soil:
The decline in soil moisture has been happening on a large scale worldwide, as reported in the journal Science, here: Abrupt sea level rise and Earth’s gradual pole shift reveal permanent hydrological regime changes in the 21st century | Science
You can’t tell it from the headline, but the focus of the study is terrestrial water storage, the amount of water stored on and in the land.
4,000 cubic kilometers of water worldwide … is a LOT of water
They report that the soils of the world lost 2,623 billion tonnes of water between the years 2000 and 2016. This translates to 2,623 cubic kilometers of water lost from the “land,” i.e., the soil.
Extrapolating just a bit, assuming these trends have continued from 2017 to the present, we are looking at a loss of perhaps 4,000 billion tonnes, or 4,000 cubic kilometers of water lost from the soils of the world, since the year 2,000.
Missing the forest for the trees, missing the big picture amid the details
The sad part is the gross misinterpretation. These otherwise intelligent people (scientists and reporters) reveal no understanding of what regenerative farmers know: that healthy soil holds water, and lots of it.
Healthy soil holds water
As reported by the US Department of Agriculture, healthy soil (as measured by the percentage of soil organic matter) holds monumental amounts of water.
“One percent of organic matter in the top six inches of soil would hold approximately 27,000 gallons of water per acre.” —USDA Natural Resources Conservation Service, “Soil Health Key Points,” February 2013
Empty spaces hold both air and water in the soil
Healthy soil is about 40% empty spaces or pore spaces. These pore spaces hold some combination of air and water. When it rains, healthy soil can soak up water and hold onto it. By contrast, unhealthy, degraded soil does not have pore spaces, at least not as many. So rain runs off and never soaks into the ground.
This is why regenerative farmers and ecologists measure water infiltration rates. They want to know how fast water soaks into the soil. This is called infiltration.
The right idea, poorly implemented
As indicated above, the United States Department of Agriculture knows this. At least parts of the department know this, i.e., the Natural Resources Conservation Service (NRCS). Formerly known as the Soil Conservation Service, the NRCS was established in the depression era, in the Franklin Delano Roosevelt administration to address the catastrophic loss of soil known as the Dust Bowl, which occurred in the Great Plains of the US from 1930 to 1936.
Roosevelt declared, “A nation that destroys its soils destroys itself.” Unfortunately, neither he nor the people at the Department of Agriculture ever learned how to conserve the soils--not really--until the likes of Ray “the Soil Guy” Archuleta came along and, with Gabe Brown, author of Dirt to Soil, taught us the Five Principles of Soil Health.
Healthy soil holds water!
To get the soil to soak up the rainfall, employ these principles.
The Five Principles of Soil Health include the following:
Avoid disturbance, including physical disturbance, like tillage, and also chemical disturbance such as synthetic fertilizers and pesticides.
Armor the soil surface. Don’t allow the ground to be bare. Cover the ground with some sort of organic matter, such as leaves, crop residues or wood chips.
Keep living roots in the ground. Plant roots exude carbon compounds into the ground, feeding the all-important bacteria and fungi and giving life, food, calories and nutrients to the soil food web, the underground ecosystem.
Build diversity, starting with a diverse community of plants. Don’t rely on one species of plant to keep your soil health. Grow diverse communities of plants, for example a multi-species mix of cover crops.
Incorporate animals. All ecosystems have animals. It is a mistake to try to grow crops, or pasture, or a forest in the complete absence of animals.
Using these principles in your garden
In this article, I wrote about how I apply the principles of soil health in my home landscape: Pollinator Garden Update: Improving Soil, Using the Most Prolific Plants.
The point is that wherever you have soil, you have the opportunity to improve the soil. And when you improve the soil, the soil holds more water--a LOT more water.
This point is lost on the authors of the study and the Washington Post writers who reported on the study.
Are these losses “irreversible”?
The Washington Post reported on the study in this article: Earth’s soil is drying up. It could be irreversible. - The Washington Post. They wrote:
“The amount of water stored on lands across Earth’s continents has declined at such staggering levels that changes are likely irreversible while humans are alive, a study published Thursday found.” (emphasis added)
Emphasis on the words “changes are likely irreversible.”
They are saying that soil moisture is declining and that there is no way to reverse the downward trend.
This is the same thing as saying that there is no way to improve the soil, because of (Wait for it!) climate change, the all-purpose scapegoat.
Do climate change and drought impact soil moisture?
The Post goes on to say:
“The losses in soil moisture — a result of the planet’s climate conditions and prolonged droughts — already pose issues for farming, irrigation systems and critical water resources for humans.” (Emphasis added.)
They misunderstand the problem. While it is true that climate change and drought can affect the condition of the soil, they miss the most important factor: soil health.
Soil health matters more than climate and weather
What matters more than climate and weather, drought and precipitation, is how you treat the soil.
Is the ground bare? Does the ground have a diverse community of plants? Are we attacking the ground with tillage, chemical fertilizers and toxic pesticides?
How to assault the soil of the forest
Another way of disturbing the ground is taking heavy equipment into forests to practice “forest thinning,” in an ill-advised, futile and counter-productive effort to suppress forest fires. This heavy equipment is a form of disturbance that compacts the soil, degrading the soil and compromising the ability of the soil to hold onto water.
Also, the process of forest thinning--and all logging--is a process of removing organic matter from the forest. When you remove organic matter such as leaves, limbs and logs, you degrade the plant community and degrade the soil, compromising the forest’s natural ability to improve the soil and hold onto water.
The original study--not just The Post--blames climate for the loss of soil moisture
In the original study (Abrupt sea level rise and Earth's gradual pole shift reveal permanent hydrological regime changes in the 21st century - PubMed), they report:
“ ... SM [soil moisture] has not recovered as of 2021, with future recovery unlikely under present climate conditions.” (Emphasis added.)
In other words, they are attributing this loss of soil moisture to the climate and not the health of the soil. The climate includes prevailing temperatures and precipitation. Temperature and precipitation have an impact on soil. But soil health has a greater impact on soil.
Healthy soil holds water, plain and simple. The rest is details.
It is concerning when otherwise intelligent, informed, trained, capable and discerning people misunderstand an issue that is so fundamental to the subject of their study.
When highly trained scientists tell me the world has lost over 3,000 cubic kilometers of water, I pay attention. But I also pay attention when they demonstrate no apparent understanding of how soil gains or loses water.
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To RSVP for today’s free webinar, please click here: The Worldwide Loss of Soil Moisture: Friday, October 17 @ 3:00 PM (Eastern Time)