The Soil Food Web on the Farm
GreenFriends Farm was happy to host Dr. Elaine Ingham once again on February 29th-March 4th. Dr. Ingham is a world-renowned soil biologist and the founder of Soil Food Web, Inc. This was the ninth year in a row that she has come to the Farm to teach a week long workshop on the soil food web. The soil food web is the intricate network of organisms above and below ground that provide the basis for all plant life on earth and therefore most life.
People came from across the country, and even from as far away as Norway, to participate. The workshop featured hands-on lectures on the soil food web, composting, compost tea and microscopy. Participants learned how to make and evaluate good compost that benefits the right microorganisms for their plants needs.
Soil does not equal dirt. “Dirt is the four-letter-D-word in soil science,” Dr. Ingham explains. Dirt is what accumulates on your hands, clothes and shoes. As it gets tracked inside the biology dies. The difference between soil and dirt is that dirt lacks the soil food web which includes the proper microorganisms that are required for plants to grow.
The soil food web is directly involved in getting nutrients from the soil to the plants and eventually to you. Plants convert sunlight into sugars through photosynthesis. The plants then secrete these sugars through the roots as exudates. The purpose of the exudates is to feed fungi and bacteria around the root system.
The bacteria and fungi extract nutrients from the soil and decompose organic matter. They help keep nutrients in the root zone so that they are available to plants, rather than lost or leached out into groundwater. They also enhance soil structure by binding soil particles into aggregates, thereby improving the flow of water and oxygen and preventing waterlogged, anaerobic soil where these beneficial organisms cannot survive. The bacteria and fungi compete with disease causing organisms and plant pathogens, leading to stronger healthier plants.
Protozoa, nematodes, microarthropods and earthworms are considered predators in the soil food web because they eat the bacteria and fungi. This causes the release of the nutrients that were stored in the bacteria and fungi, in a soluble, plant available form. Because they are larger organisms, they further improve soil structure by burrowing and creating air and water passages. They also enhance decomposition of organic matter and mix it into the soil.
That is all very fascinating, right? But why does it matter to you?
“Nutrition,” Dr. Ingham emphasizes. “That is what people really need to understand. Only if we put the biology back in the soil will the food we are eating have balanced nutrition.”
On the last day of the work shop participants made up soil samples to look at under the microscope. Putting those soil samples under the microscope was proof that everything they had learned in the past few days was true. The soil is alive.