“If there were a United Federation of Organisms, humans would be voted off the planet.” –Paul Stamets

One of Earth’s greatest treasures is soil—without it, we could not survive. Soil is the mother of nearly all plant life, and ultimately all animal life on Earth. It’s the interface between biology and geology, the living skin of our planet.

A new documentary, “Dirt! The Movie,”¹ brings to life the environmental, economic, social, and political impacts of soil. Sharing the planet with humanity has all but placed soil on the “endangered species list,” due to greed, ignorance, and lack of respect for the earth.

Our very lives depend on the top five centimeters of soil, which keeps our biosphere healthy and teeming with life. Soil is quite literally a matter of life or death—our life or death. India calls its soil “Sacred Mother” because it’s the source of all fertility.

We’ve lost one-third of our topsoil over the last century as a result of industrialized agriculture, monocropping, erosion, and deforestation. Each year, 100 million trees are turned into 20 billion mail order catalogs.

Instead of being narrowly focused on growing food, we should be putting our efforts into building and restoring healthy soil. Not only is healthy soil necessary for nutritious food, but it has other important functions across the globe.

Dirt Can Also Provide Materials for Homes

People have been building with dirt for more than 9,000 years. One-third of the world’s population still lives in earthen structures.

Earthen dwellings are made from local materials, often from the very ground you’re standing on. Earthen homes are undergoing a revival due to the rising costs of fuel and building materials. Materials such as cob and adobe are the most commonly used building materials worldwide.

Earthen structures are cool in summer and warm in winter, ideally suited for passive solar heating and cooling. They are clean, attractive, and strong, often capable of withstanding the elements for hundreds of years.²

Cob is a simple building material made from clay-rich soil and typically straw that can be stomped into place to create earthen walls. Cob structures are extremely durable, many surviving centuries in harsh British coastal climates.³,⁴

Cob is abundant, inexpensive, nontoxic, and doesn’t contribute to deforestation, pollution, or mining. Building with it doesn’t demand the use of manufactured materials or power tools.

In India, mud plaster is made from a mixture of mud and cow dung and is often “painted” in layers upon earthen floors to build a hard, resilient surface. The dung even acts as an antiseptic to help prevent infestations.

Thanks to the cows, the fiber in the dung is processed extremely fine, and its “pre-treatment” with enzymes and other proteins creates a natural glue that dries very hard.

Similar to cob, adobe is made from sand, clay, water, and fibrous organic matter such as sticks, straw, or dung. Adobe is commonly used in hot climates, such as the American Southwest, Mexico, South America and Africa.

One Tablespoon of Healthy Soil Contains 50 Billion Bustling Microbes

“One handful of terrestrial dirt contains more organized information than the surface of all the other planets combined.” – Dirt! The Movie

Soil cannot be taken for granted—it isn’t everywhere. Most of the planet’s surface actually consists of solid rock, upon which most plants can’t grow. Soil starts with a mineral source—weathered rock, glacial silt, river sediments, or sand—but it isn’t soil until organic matter is added.

This slow infusion of organic matter is why soils can take hundreds, or even thousands of years to develop. Unfortunately, toxic agricultural practices can destroy it in a few years!

Healthy soil is about 50 percent solids and 50 percent air and water. Organic sources can be living or non-living. Old leaves, dead animals, and tiny living things all enrich the soil with its necessary carbon supply. Microbes must have a constant supply of organic matter or their numbers will decline.

At present, the world’s soils have lost 50 to 70 percent of their carbon, much of which is now in the atmosphere as carbon dioxide. Soil houses thousands of organisms—bacteria, protozoa, fungi, nematodes, and arthropods—all playing unique roles in the continual recycling of organic matter, most being smaller than the head of a pin.

Soil microorganisms are key in making nutrients available to plants and are so diverse that 70 to 80 percent have yet to be identified. It’s estimated that one tablespoon of soil contains about 50 billion microbes.⁵

Fungi play a particularly important role. More than 90 percent of land plants are nourished by mycorrhizae, a symbiotic form of fungi that helps move nutrients from the soil into the roots of plants.

Soil microorganisms are critical to numerous processes, including releasing essential nutrients and carbon dioxide, nitrogen fixation, nitrogen and phosphorus cycles, denitrification, immobilization, and mineralization.