“Reality leaves a lot to the imagination.” – John Lennon.

soil

Soil has super-powers. As a gardener, I’m passionate about compost, but it wasn’t until I read Judith D. Schwartz’s book Cows Save the Planet: And Other Improbable Ways of Restoring Soil to Heal the Earth that I realized there is so much more to soil. Yes, it produces renewable resources, sustains biodiversity, and provides us with the inputs we need for good health. But it also lessens the impacts of floods and droughts, and reduces the severity of climate change through carbon sequestration. Pretty impressive!

It can even be the source of powerful medicine. In late June 2014, we heard of a fungus found in Nova Scotia soil that may help fight antibiotic-resistant superbugs. Who knows what other super-powers may reside in soil.

But centuries of abuse have reduced the Earth’s soil to a sorry state. We’re losing topsoil 10 to 40 times faster than it is being generated, depending on your location. (Globally, it’s the equivalent of an area larger than Australia every single year.) Wind and water erosion steal soil from bare fields. But humus is also lost as carbon in the soil oxidizes and enters the atmosphere. Dr. Rattan Lal, Professor of Soil Science at Ohio State University, has calculated that conventional farming and grazing practices over the last 150 years have contributed about 1.76 times more carbon to the atmosphere than from burning fossil fuels.

In creating a sustainable society, there may be nothing more imperative today than to build soil. To do that, we will have to make sweeping changes to how we use it.

First, we need to understand what soil is. As opposed to lifeless dirt, soil is an interdependent ecosystem, teeming with life. Imagine: one teaspoon of soil can have as many living organisms as the number of people on Earth.

Perhaps, the most amazing organism of all in soil is root fungus known as mycorrhizal fungi (MF). About 80% of all land plants form vital symbiotic associations with it. MF is comprised of long thread-like filaments (hyphae) that dramatically increase a plant’s access to water and nutrients. In return, plants provide MF with dissolved organic carbon from photosynthesis.

A plant with an MF partner can transfer 15 times more carbon to soil than one without through a process called the “liquid carbon pathway”. Carbon is stored in a secretion called glomalin that coats the delicate hyphae. This liquid carbon in the soil also feeds other microbes that break down rock into soluble minerals needed by plants.

Glomalin was just discovered in 1996 by the USDA’s Agricultural Research Service. In addition to storing carbon, it acts like super-glue, binding soil particles together in clumps, thereby making them resistant to erosion, but also improving air and water flow through soil.

As if that weren’t enough, MF also provides plants with disease resistance through the release of antibiotics.

Conventional farming methods destroy MF, and with it the vibrant soil ecosystem. Tilling shreds its delicate filaments. Without plant cover, the fungus starves to death. And heavy use of fertilizer inhibits its growth.

Without MF and the use of appropriate amendments to soil, our food is losing nutritional value. A landmark study by the Department of Chemistry and Biochemistry, University of Texas, found for 43 different vegetables and fruits “reliable declines” in the amount of protein, calcium, phosphorus, iron, riboflavin (vitamin B2) and vitamin C over 1950 to 1999. Not a single nutrient had increased in the 50 year time period.

The good news is that soil (and the nutritional content of plants) can be built up rapidly by cultivating a vibrant soil ecosystem. With MF plant partners, 30-40% of carbon in green leaves can be transferred to soil. In fact, humus can be generated at depths below 30 cm more rapidly through the liquid carbon pathway than through decomposition at the surface. Carbon that is returned to the soil by this method is far more stable (less prone to oxidation) thanks to MF and glomalin.

In order to generate the data needed to sway land managers toward soil building practices, a nonprofit organization called the Soil Carbon Coalition was formed. Over 60 participants from USA, Mexico and Canada are taking part in the Soil Carbon Challenge, a “10-year monitoring program that will advance the practice, and spread awareness of the opportunity, of turning atmospheric carbon into soil organic matter.” (The Soil Carbon Coalition offers a participatory workshop for interested communities. To learn more, contact Peter Donovan at info@soilcarboncoalition.org or visit http://soilcarboncoalition.org/workshop.)

Homeowners can play a part too. Use groundcovers and close plantings to eliminate bare ground (which leads to carbon oxidation), minimize soil disturbance and the use of synthetic fertilizers, inoculate soil with commercial MF products such as Myke and pull out garlic mustard, an invasive species that produces cyanide compounds which suppress MF.

We cannot see firsthand the full richness of life. But science gives us a window onto hidden species vital to our wellbeing. With imagination, we can learn to love the mycorrhizal fungus among us!

Advertisements