Living Soil--Why We Want to Be Outnumbered

Dr. Pat Richardson of the University of Texas at Austin has travelled around the country helping people understand what is going on underground in soil. She uses a video camera that can capture the microscopic crittes in the soil and show their important work of cycling minerals in the soil. Plant roots bring up mineral nutrients above ground, making vegetation, but they do not accomplish this by themselves. They actually need livestock to cycle minerals. There are livestock of all kinds—microfauna (microscopic animals, fungi, and bacteria), mesofauna (macroscopic soil invertebrates such as earthworms and nemotodes), and megafauna (large animals). A teaspoon of healthy soil can contain 100 million bacteria. When they are allowed to grow naturally, they build communities of multiple kinds. They build towers, move liquid, communicate, and create protective sheaths to fight off other bacteria, protozoa, and antibiotics. This is why some bacteria are more resistant to antibiotics. Given the duties these bacteria perform, it is essential that we think about how we’re managing them. Why would we care if our soil has lots of bacteria? First, bacteria have more nitrogen in them than any other living organism we know of. They have about five carbons to one nitrogen, whereas humans have roughly 30 carbons to 1 nitrogen. Bacteria sequester the nitrogen that you want in soil. And because of the protective sheath, bacteria do not leech when it rains, and the nitrogen stays in place. Dr. Richardson explains if you have sand, silt, and clay parent material of soil and you pass liquid calcium though, all of it leeches through. If you add organic matter, good cationic exchange capacity to your sand, silt and clay and pass calcium through, 95% passes through. If you add bacteria, 90% passes through. But add fungi, and only 5% passes through. Fungi hang on to calcium and are essentially the “highways” to getting it to the roots of plants. Joel Salatin is quoted as saying, “Production needs to be light on the landscape.” But when we rip up grass through tillage, we damage root structure. What are we doing to its collaborative structure that is bringing nutrients and water to those plants and which also extends the capacity of every plant to get water from the soil? What communities are we ripping up? If healthy soil is part of our holistic goal, part of our resource base to achieve our desired quality of life, then what management techniques will help us improve soil life, not damage it? To learn more about this and other topics, subscribe to IN PRACTICE