The Soil Food Web

Image courtesy of the Lexicon of Sustainability

Elaine Ingham and the Soil Food Web. Image courtesy of the Lexicon of Sustainability

At least once per year the Chico Permaculture Guild hosts a gathering centered around the Soil Food Web. Check out our monthly gathering schedule to see when we will host this particular free educational topic again.

I had the great fortune to attend a course taught by Dr. Ingham in late March 2014. It was the last day of a week long soil food web intensive and was all about how to use a microscope to identify the soil microbes that live in our soil, compost and compost tea. Identifying the good guys from the bad guys is not as hard as it may seem.

At our Soil Food Web Gatherings we talk about all the critters that make up the soil food web. Then we give everyone a chance to actually see these amazing creatures live and in-person using a microscope. We have a microscope hooked up to a computer and live samples are projected onto the big screen.

Some of you may be asking, “What’s the point of seeing these guys through a microscope, I don’t have one at home?”. Or “I’m no biologist, how am I supposed to know what I’m seeing?”.

We feel it’s important to show you what soil microorganisms look like and just how simple it is to take samples and how to view them. We won’t be able to teach you everything about microbiology (that is beyond me too) but we can give you enough information to understand what you’re seeing and how to do it on your own. With the hope we inspire some of you to go out and get a hold of a microscope to view your own soils and compost. Or even seek out those of you who are interested in purchasing a microscope and you could cooperatively buy and share one.

One of the soil study microscopes recommended by Dr. Elain Ingham 40X-400X Compound LED Siedentopf Microscope+Built-in 3MP Camera available for $389 at Microscope.net

One of the soil study microscopes recommended by Dr. Elaine Ingham 40X-400X Compound LED Siedentopf Microscope+Built-in 3MP Camera available for $389 at Microscope.net

It’s actually quite inexpensive; less than $400 investment to reduce or eliminate purchasing amendments for your soil. It’s a worthy return on an investment that could potentially save you hundreds of dollars in the future. Once you know who the good guys are and what kinds of foods they like you can literally feed your soil high quality compost and compost teas/extracts. ONLY. No more additions of rock phosphate, lime, gypsum or N-P-K fertilizers. EVER AGAIN.

Despite what a conventional soil lab report indicates, all soils around the world contain plenty mineral nutrients for plant health. Most often the nutrients are simply locked up in a form plants cannot use. Microbes are the key to unlocking those nutrients and making them available in a soluble form that plants can uptake through their roots. As Dr. Ingham has stated in her many lectures, there is no place on our Earth that is deficient of essential plant nutrients, they are only lacking the soil food web critters that make nutrients available for plants.

SO, WHAT IS THE SOIL FOOD WEB?

soil food web image_2Soil is by far the most biologically diverse part of our Earth. Within and around the soil live critters we can see like beetles, mites, worms, spiders and ants but the soil also hosts tiny microscopic organisms -microbes for short- like bacteria, protozoa, nematodes, fungi, and microarthropods. All of these organisms, big and small, improve the entry and storage of water, resistance to erosion, plant nutrition, and the break down of organic matter.

Did you know there are more soil microbes in ONE TEASPOON of healthy soil than there are people on the Earth!?! That’s a huge, living, breathing, waste producing work force! Which is what they are doing for our plants everyday.

HOW DO THEY PROVIDE NUTRIENTS FOR OUR PLANTS?

Plant roots produce exudates (sugars, proteins and carbohydrates also called “cakes and cookies” by Dr. Ingham) that attract certain microbes to the plant root systems. While the microbes are gathered around the roots eating the sugars (or the bacteria or each other) they’re also drawing more friends (or enemies) toward them -and ALL those microbes are breathing and pooping all the time. Which is exactly what the plant wants. The plant reaps the benefit of soluble nutrients (microbe waste) for it’s own growth and health. The plants live out their lives both above and below ground, producing organic matter, fruits and seed which feed birds, cows and humans alike. THIS IS THE SOIL FOOD WEB. And we, humans, are intricately entwined with this web and must be good stewards of our soil.

Here is a glimpse of some of the critters we hope see at our one of our Soil Food Web Gatherings:

BACTERIA: Feed on organic matter and store and cycle nitrogen

A ton of microscopic bacteria may be active in each acre of soil. Credit: Michael T. Holmes, Oregon State University, Corvallis. Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, IA: Soil and Water Conservation Society

A ton of microscopic bacteria may be active in each acre of soil.
Credit: Michael T. Holmes, Oregon State University, Corvallis.
Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, IA: Soil and Water Conservation Society

PROTOZOA: Eat bacteria, fungi, and algae

Protozoa play an important role in nutrient cycling by feeding intensively on bacteria. Notice the size of the speck-like bacteria next to the oval protozoa and large, angular sand particle. Credit: Elaine R. Ingham.

Protozoa play an important role in nutrient cycling by feeding intensively on bacteria. Notice the size of the speck-like bacteria next to the oval protozoa and large, angular sand particle. Credit: Elaine R. Ingham. Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, IA: Soil and Water Conservation Society.

NEMATODES: Predatory, they eat each other as well other organisms

Most nematodes in the soil are not plant parasites. Beneficial nematodes help control disease and cycle nutrients. Credit: Elaine R. Ingham. Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, IA: Soil and Water Conservation Society.

Most nematodes in the soil are not plant parasites. Beneficial nematodes help control disease and cycle nutrients.
Credit: Elaine R. Ingham.
Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, IA: Soil and Water Conservation Society.

FUNGI: Up to 3,000 species of fungi are in the soil performing various functions

Fungus beginning to decompose leaf veins in grass clippings. Credit: No. 48 from Soil Microbiology and Biochemistry Slide Set. 1976. J.P. Martin, et al., eds. SSSA, Madison WI. Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, IA: Soil and Water Conservation Society.

Fungus beginning to decompose leaf veins in grass clippings. Credit: No. 48 from Soil Microbiology and Biochemistry Slide Set. 1976. J.P. Martin, et al., eds. SSSA, Madison WI.
Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, IA: Soil and Water Conservation Society.

MICRO-ARTHROPODS: Decompose and shred organic matter and eat microbes

This pale-colored and blind springtail is typical of fungal-feeding springtails that live deep in the surface layer of natural and agricultural soils throughout the world. Credit: Andrew R. Moldenke, Oregon State University, Corvallis. Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, IA: Soil and Water Conservation Society.

This pale-colored and blind springtail is typical of fungal-feeding springtails that live deep in the surface layer of natural and agricultural soils throughout the world. Credit: Andrew R. Moldenke, Oregon State University, Corvallis.
Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, IA: Soil and Water Conservation Society.

Macro-arthropods and earthworms also play an important role in the soil food web. They are large and easily found in the soil, when it’s healthy, so we won’t be viewing them at our gathering but we will be talking about their functions in relation to the other microscopic critters in the soil.

One of the best to places to begin learning about the soil food web online is from the Natural Resources Conservation Service (NRCS) website. The Soil Biology Primer is an invaluable tool for information and resources about soil biology and the soil food web. I’ve utilized images above from the Primer (with permission).

I hope you will join us at our next Soil Food Web Gathering and that you will be able glean some valuable information about the importance of healthy soil and the critters, big and small, who inhabit the soil and who work hard for us every day. Healthy soils are the foundation of a healthy food system and the key to a food system that is not only more resilient to a changing climate, but also healthier for us and the planet.

I would like to thank the Soil and Water Conservation Society for granting me permission to use their photos in this post.

~Stephanie Ladwig-Cooper, CPG lead organizer and co-founder

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