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We have all heard of microbes… acidophilus in yogurt, yeast in bread dough, scrubbing bubbles in the bathtub, and even beneficial microbes for our soil. We hear probiotics are good for our health, and antibiotics cure infections, but what’s the real deal on microbes and our soil?
The real deal is that without soil microbes, we would all die. The work they do in our soil is incredibly complex but it all boils down to this: microbes eat, thus we eat. Plants are unable to take from the soil the nutrition they need without microbes working in the soil. Microbes are alive, and must have nutrition to survive, and that nutrition comes from organic matter. As they consume the nutrients they need, microbes create foods like nitrogen, carbon, oxygen, hydrogen, phosphorus, potassium and trace minerals for our plants. It is the microbes that convert the NPK and minerals in the soil into a form our plants can use to grow and produce food and flowers for us.
Microbes
Microbes are everywhere. They are in the air, in the rivers and oceans, in our drinking water, in the soil, and on our skin. Of course we know some microbes are bad, like e. coli and salmonella, but more are considered beneficial and out-compete pathogens for survival in the soil. There are all kinds of microbes, like algae, protozoa, bacteria and fungi, with many others waiting to be discovered. Their populations in soil are numerous: as many as one billion of up to 13,000 species can reside in a single gram of soil.[1](1 gram = 0.0022 pounds, so maybe a teaspoon?)
Compostable garden waste
Garden compost
Muck from horse stalls
Most microbes need organic carbon to live; they get this from eating wood chips, leaves, manures and other organic materials added to the soil. As microbes digest organic matter, they create humus which increases soil structure, good for root penetration and development. (Compaction can nullify much of this action.) Microbes also get some carbon from the rhizosphere (the area immediately around plant roots) because roots give off substances the microbes can use, like sugars and amino acids... and then the microbes convert some of it back in forms the plants can use, as minerals, vitamins, nitrogen and amino acids. (Amino acids are the building blocks of protein. Humans need 20 amino acids to make muscle, hair, skin, and connective tissue, and human bodies only make 10 of them. The others must be supplied by food from plants and animals.[2])
Some microbes (like some bacteria and blue-green algae) are able to “fix” nitrogen from the air and make it available to plants. Some plants and trees cannot grow if deprived of specific microbes (mycorrhizal fungi) around their roots. That’s why some plants need a good shovelful of additional soil from around their roots for company when transplanting. There are microbes that break down contaminants and toxins, like oil spills and toluene from gasoline leaks. The word for that action is bioremediation and research is ongoing to select microbes that digest other toxins in our soils.
Fungi
There are many garden products available containing beneficial microbes for the soil. Some are in the fast-acting form of foliar sprays, and some are home-brewed compost teas used to spray or drench. In all cases, foliar sprays are not enough; there must also be organic matter continually available in the soil for the microbes to eat. The leaves, compost and/or manure you added last summer need continual replenishment. Microbes multiply, and if your microbe population is low due to lack of organic matter, it can be easily rectified by amending the soil with organic matter and allowing time for microbial growth. Jump-starting the reproduction of microbes by adding beneficial microbes along with organic matter is an option depending on how soon you want to see results, and the cost.
We can readily say that microbes are the workhorses of our gardens. Microbes make nutrients in the soil available to plants in a form the plants can use. Microbes create some of those nutrients, and we (with Nature’s help) add the rest. Because the plants are healthier, they resist disease better, and tolerate environmental stress better. Microbes improve soil structure by the humus they create while digesting organic matter. Microbes help in nitrogen fixing.
I have a 'growing my own food' obsession that comes from my overlapping interests in cooking, nutrition and gardening. I am also a "teacher", a writer, a builder… and a craftsperson and... and… and many other things, LOL. In fact, I guess I am a generalist, and a Seeker.
I live in the southern Appalachian Mountains on a hillside with a creek in front, and drive a 15 year old truck I lovingly call “My Farmer’s Ferrari.”
Posted by Pamgarden (from Central, VA) on December 03, 2008 at 05:43 PM:
Darius, This is the first time I've seen your new picture with your article. You look great. I always enjoy your articles. I love all articles on improving my soil. Pam
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Posted by darius (from So.Appalachian Mtns, VA) on December 03, 2008 at 06:22 PM:
Thanks, Pam... look for a few more soil articles coming up.
Pic is not too new, but I love it. :)
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Subject: nice
Posted by phicks (from Lakeland, FL) on December 03, 2008 at 04:44 PM:
Good Aritcle Paul
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Posted by darius (from So.Appalachian Mtns, VA) on December 03, 2008 at 06:23 PM:
Thanks, Paul. You are always quick to hand out praise...
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Subject: thanks
Posted by Dutchlady1 (from Naples, FL) on December 03, 2008 at 07:13 AM:
now I know WHY the horse manure is good for my garden!!
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Posted by Fitsy (from Hayesville, NC) on December 03, 2008 at 09:27 AM:
Yes, thanks for the reassurance that we are on the right track with
the chips and stuff, and thanks for spelling out some details for us.
Fitsy
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Posted by Sundownr (from (Bev) Wytheville, VA) on December 03, 2008 at 10:01 AM:
Darius, Thanks for reminding us why we need to be good to the ground, and that we are really feeding what feeds us!
Bev
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Posted by LariAnn (from Miami, FL) on December 03, 2008 at 11:33 AM:
Hi Darius,
Thanks for a great introduction to microbes and their importance to us. I feel that even the "bad" microbes serve a "good" purpose in that they indicate the presence of an imbalance in the system. A healthy system/organism will have a natural balance of microbes and won't allow for the "bad" microbes to gain an upper hand, while one out of balance will provide an environment favorable for the dominance of pathogens. They are like biological warning signals, indicating that something is amiss.
LariAnn
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Posted by darius (from So.Appalachian Mtns, VA) on December 03, 2008 at 11:56 AM:
Thanks, folks. This is just the beginning of several short intros into soils and soil chemistry; I hope they will all be as well received.
LariAnn, of course you are correct. I have some detailed info. about the good/bad microbe balance and how/why it works. Might be enough for an article tying everything together after the chemical intros are finished.
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Posted by gloria125 (from Greensboro, AL) on December 03, 2008 at 03:52 PM:
Yes. Thanks. Its good to know what goes on in there!
I guess you can't buy it in a sack at the Farmer's Co-op.
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Posted by darius (from So.Appalachian Mtns, VA) on December 03, 2008 at 06:24 PM:
Probably not there, but soil microbes are sold online...
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Posted by mellielong (from Lutz, FL) on December 03, 2008 at 07:46 PM:
I've trained my family to put all their kitchen scraps in the compost bin. Dad told me when they were on vacation recently they felt bad about throwing the stuff out! This weekend Dad is taking me to my horse compost connection (found via craigslist) to get our second trailer load of composted manure. Dad finally gave me a plot to grow a real vegetable garden (as opposed to the small raised beds I used previously). I really want to plant some seeds, but I promised myself I would get my soil in top shape before I planted. This article reminded me why I have to be patient and feed my soil before I feed myself (with yummy fresh veggies)! I still can't believe how I turned from such a "girly girl" to the person who tucks earthworms back in the soil when I accidentally dig them up, LOL!
Melanie
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Posted by darius (from So.Appalachian Mtns, VA) on December 03, 2008 at 08:34 PM:
That's great progress, Melanie! I wish I had put the horse before the cart myself. Retrofitting garden soil is a lot more work.
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Posted by mellielong (from Lutz, FL) on December 03, 2008 at 08:56 PM:
Well, I've learned a lot from the folks on the composting forum. I've never been the most patient person, but gardening certainly helps. Plus, in it's own way it's fun to watch the soil "grow". Since I have pure Florida sand it's fun to watch it turn black and rich and to dig and find bugs and worms instead of nothing (or fire ants!). Plus, we're always trying to conserve water and compost keeps the moisture in rather than draining straight through the sand. Florida is also one big chunk of limestone so I'm hoping compost will help neutralize the soil.
Melanie
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Posted by pajaritomt (from Los Alamos, NM) on December 03, 2008 at 10:08 PM:
Great article as usual, Darius. In New Mexico, where the soil contains very little organic matter, one cannot grow much of anything, except natives, unless one feeds the soil. After a year or two of total garden failures, I learned that chemical fertilizer just isn't enough in New Mexico. Once I started using manure and eventually compost, I found my self having a lovely garden by anyone's standards. I had to learn about soil bacteria the hard way, but I got the message.
One learns to get whatever organic matter one can get and to compost it if it isn't immediately usable. Lawn clippings, fall leaves, animal bedding materials, manure, wood chips. Then one learns which can be used immediately and which we must allow the bacteria to work on before we put them on our crops.
Luckily we don't have to buy most bacteria. They simply come out of the air or soil when we create a good environment for them, even here in a near-desert environment.
One of the most interesting things I have discovered is that if you pile up layers of manure and leaves ( and other stuff) and make it big enough, the bacteria eating them will produce a measurable amount of heat even through most of the winter. I got a compost thermometer to test that and it really is true. If you have built it properly you can watch your compost pile steam as it melts the blanket of snow over it.
We gardeners grow more than veggies and flowers!
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Posted by darius (from So.Appalachian Mtns, VA) on December 03, 2008 at 10:13 PM:
pajaritomt, good point to mention the heat produced! Thanks.
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Posted by pajaritomt (from Los Alamos, NM) on December 03, 2008 at 10:17 PM:
You know, darius, I once read an article about a former New York City landfill. This is not a carefully constructed compost pile but a bunch of garbage of all kinds covered up by a layer of soil. That landfill is noticeably warmer than the surrounding soil and the snow melts on it much faster than on the surrounding soil. Says a lot about how much those little bacteria do when we aren't thinking about them.
