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Soil Bacteria – The Myth of Identification & Managment

Bacteria are a vital part of soil and the health of plants, so it is no wonder that there is a lot of talk about keeping soil bacteria healthy, increasing their numbers, having the right kimnd of bacteria, and so on. It only makes sense that if bacteria are important for plants, gardeners should (a) know more about them and (b) learn to manage them properly.

Unfortunately, along with good practical information, you will also find quite a few soil bacteria myths. The one I’d like to discuss today deals with the idea that you can figure out which type of bacteria you have. Armed with this information, you can then manage the populations to increase the ones that are most beneficial for your plants.

Soil bacteria staring back at you under a microscope

Soil bacteria staring back at you through a microscope

Soil Bacteria and Dr. Elaine Ingham

Dr. Elaine Ingham has become synonymous with the Soil Food Web. Her teachings include many good ideas about keeping soil healthy. She is a proponent of compost, and adding organic material to soil. She promotes the idea that microbes in the soil are very important for developing good soil structure.

Unfortunately, Dr. Ingham then takes these ideas to a ridiculous extreme. She recommends gardeners should look at the microbes with a microscope, and with this device, they will be able to identify the various bacteria in soil. Once you know which bacteria you have in your soil you can take steps to manage the herd, and increase the right ones which would make the growing conditions more favorable for your plants. She goes on to suggest that different plants need different populations of bacteria and gardeners can learn to customize their soil.

Here is a quote from the advertisement for one of her courses where a full day is dedicated to identifying microbes: “Get the necessary training to identify the bacteria, fungi, protozoa, and nematodes that drive the health and well being of our plants” (ref 1, Soil Foodweb with Dr. Elaine Ingham).

I have no problem with the idea that microbe types in soil are important, and that their ratios might change over time, and that such changes influence plant growth. This is all very true.

What I have a problem with is the idea that anyone can control this situation in a quantitative way. To do this you need to be able to identify the current bacterial types that you have, and then influence their populations to make them more suitable for you plants.

Note: Added March 28, 2016. A couple of comments left at the end of this post said that Dr. Ingham does not promote the identification of species. I now think that is correct.

The commenters can’t imagine where I got such an idea. So I went back and looked at a lot of the promotion from Dr. Ingham, and looked at several online videos. In every case she talks about the ‘identification of microbes’. In the video she clearly differentiates between various types of bacteria, and nematodes and talks about the importance of identifying these various types, and how this can be learned using a microscope. Clearly she expects you to do much more than just count total bacteria and total nematodes as one commenter said.

From her web site: “we will develop a wider and wider base of knowledge as more people encounter all the myriad of organisms that exist in soil.  Which in turns leads to a better understanding of what exactly is in different soils, in different climates, and with different organic matter and plants.” Sounds like a lot more than just counting bacteria, fungi, protozoa and nematodes!

The Soil Food Web also talks a lot about ‘increasing diversity’ of microbes. If you don’t know which species you have how can you know that your methods are increasing diversity? You can’t, which would lead a reader to think they are doing much more than just counting total bacteria.

I think this is a case of misleading the reader/viewer about her courses. I don’t think it is intentional.

What about the rest of this post? If identification of species is not the goal, are the comments still valid? I think they are. The post is mostly about gardeners using the information gained from the microscope.

I have just finished reviewing the book Teaming with Microbes, a gardeners Guide to the Soil Food Web and they say the following about using a microscope “when it comes to the microorganisms, we will be the first to admit that you will not be able to determine precisely what is in your soil, even with a powerful microscope.“ This comment comes from two strong proponents of the Soil Food Web, Jeff Lowenfels & Wayne Lewis. I agree with their conclusion.

Bacteria in Soil

Bacteria in soil carry out some very important functions. Some are nitrogen fixers which convert the nitrogen in the air, N2, into ammonia, nitrite and eventually nitrate, so plants can use the nitrogen. The decomposers are a large group of bacteria that decompose organic matter. This process releases nutrients for the plants and improves soil structure.

Bacterial pathogens cause diseases in plants. We don’t really want them around, but they are part of nature and play an important role. Normally, the good bacteria out compete the pathogens, and keep their numbers low enough so they don’t cause a problem.

Find out more about the bacteria found in compost at Compost Microbes – Good for the Soil?

Bacteria Species in Soil

How many species of bacteria exist in soil? You would think the question would have a simple answer, but the honest truth is that scientists don’t know. Most species of bacteria have not been identified which means no one knows how to identify them.

Estimates range between 2,000 and 8.3 million species of bacteria per gram of soil (ref 2).

Identifying bacteria is so complicated that the experts use approximation techniques to figure out the number of species. It is impossible to sit down in front of a microscope and figure out which species you have. For a glimpse at how soil scientists try to estimate bacteria communities see reference 3 .

A study (ref 4, Toward a Census of Bacteria in Soil) compared soil from Alaska and Minnesota and used computer models to identify species of bacteria because doing real identification was impossible. They found several thousand species, and 20% were endemic. So the soil bacteria from these two regions were quite different from one another.

The bottom line is that no one is able to identify bacteria species by looking at a soil sample. If the experts can’t do it, gardeners can’t do it – even if they take Dr. Ingham’s course.

Types of Bacteria

OK, so you can’t identify soil bacteria at the species level, maybe you can identify them as ‘classes’ of bacteria?

You can certainly see some bacteria cell structure under a microscope, and you can form classes of bacteria based on physical structure; rods, spheres, spirals etc., but that does not really tell you anything useful about which ones you want in the garden.

You can’t differentiate aerobic from anaerobic bacteria, based on physical appearance. You also can’t differentiate between beneficial and pathogenic bacteria. Identifying a bacteria as belonging to one or the other of these classes is critical to Dr. Ingham’s methods for the management of soil bacteria, and especially for the creation of compost tea.

You can count the number of bacteria you see, but I don’t know how accurate that is for a soil sample.

The average gardener can learn very little about the bacteria in soil by looking at a soil sample under a microscope.

Professional Labs

Let us assume that I have convinced you that you can’t identify the bacteria yourself. You then have the option of using one of the labs Dr. Ingham recommends on her web site, to do this identification for you.

Here is what one of them says “Complete Food Web Test (done by SFWNY) – Quantifies total and active bacteria, total and active fungi, and presence/absence of protozoa” , ref 5 Soil Foodweb Inc – Identifying Organisms. Your results will give you 4 numbers plus a yes/no for protozoa! Remember this is a ‘complete’ test, but it does not provide any information about the identification of bacteria. Odd – maybe the testing lab never took Dr. Ingham’s course??

So even the recommended professional labs don’t try to identify species, aerobic vs anaerobic, or even beneficial vs pathogenic.Why? It’s too complicated.

Managing Bacteria in Soil

The idea that someone can take a light microscope and find out critical information about their soil bacteria is ridiculous. You can certainly see bacteria, and you might be able to count some of them. That information is not very useful.

Even if you could get the information, what would you do with it? I don’t see how you would know which bacteria you should grow for each of your plants? No such table exists. How does this change for each plant you own? Nobody knows. We don’t even know which bacteria live in your soil!

Adding more organic matter will increase the number of bacteria – you don’t need to measure them to know this. Bacteria automatically increase in numbers when you supply a food source. Having active bacteria in soil is a good thing even if you don’t know which species you have. You don’t need a microscope.

In this discussion I have focused on bacteria in soil, but all of the comments also apply to bacteria in compost tea. Except for counting bacteria, a microscope will not help you to qualify your compost tea herd. Besides, there is no current evidence compost tea works any better than just compost.

References:

  1. Soil Food web with Dr. Elaine Ingham; http://sdsustainable.org/event/soil-foodweb-with-dr-elaine-ingham/
  2. Pyrosequencing enumerates and contrasts soil microbial diversity; http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2970868/
  3. Empirical and Theoretical Bacterial Diversity in Four Arizona Soils;  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC123964/
  4. Toward a Census of Bacteria in Soil; http://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.0020092
  5.  Soil Food web Inc – Identifying Organisms; http://www.soilfoodweb.com/Identifying_Organisms.html
  6. Photo source: Filter Forge
Robert Pavlis
Editor of GardenMyths.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Myths an educational site that helps you understand your garden better.

44 Responses to 'Soil Bacteria – The Myth of Identification & Managment'

  1. David Fenton says:

    I recently watched Elaine Ingham present on YouTube. I found the soil ecology knowledge she presented to be basic and correct and as such to have profound implications concerning optimal practice in endeavours to grow plants. I researched further and found farmers such as Gabe Brown and Dave Brandt to have implemented the principles over a number of years with very good results.

    That key mainstream agricultural practices harm soil biology which when unharmed naturally fertilises and develops plants so they can be healthy enough to not need any fungicides, or pesticides etc. This shows the natural and artificial systems to be in opposition to each other. (If one promotes and establishes a natural healthy soil ecology, one can completely avoid artificial chemicals. If one uses artificials the soil biology will be harmed and there will be a need for pesticides etc which can make one dependent on buying artificials to produce)

    I did notice that Elaine promoted learning to look into soil for oneself so that people could be empowered by learning knowing and doing for themselves and so not have to rely on her own network to test their soil. The farmers who use her principles suggest a shovel and hands to know the soil health, but they do use and refer to her and others soil tests which they find useful.

    The evidence of her knowledge when put into practice shows it to beneficial on many levels such as decreasing costs to farmers, decreasing erosion, increasing water penetration and ground storage, building soil organic matter and, according to Elaine, winning US yield awards but without the $$$ fertiliser and pesticides used in modern times.

    The science from people like Elaine is becoming the new mainstream because economic, yield, sustainability, and nutrition benefits are superior. As such inferior knowledge industries, losing $$$ and diminishing due to a superior and cheaper product.

    • Re: “The science from people like Elaine is becoming the new mainstream” – some of the science is valid and has been proven. Some of her ideas can not be considered science since they have not been validated. Some of her ideas such as no-till are being adopted, but other like compost tea are anything but mainstream. Main stream farming uses synthetics.

      • David Fenton says:

        A transition to a more optimal mainstream is happening in some places.

        What is mainstream depends on where one is and at what time. In some places fertilizer is still a dominant paradigm but not in others. A couple of quotes from a pdf by Dr Christine Jones, shows that in some places farmers are discovering that much of the how they viewed soil, fertilizers, tilling, growing plants and farming was not optimal, so it is being adjusted accordingly. A couple of quotes from the article which is linked below.

        “There is an extraordinary soil health revolution taking place in North America. This farmer-led movement is receiving increasing attention and support from the United States Department of Agriculture (USDA), particularly the Natural Resource Conservation Service (NRCS). …”

        Pennsylvania farmer Jim Harbach has been using multi-species cover crops with highly beneficial results. Jim’s testimony … :
        ‘…I am very fortunate to have been part of agriculture for more than 40 years. I have witnessed the transition from conventionally plowed ground to no-till. Some of our fields have not been plowed for 40 years. We have seen first-hand the transformation of our soils, and the positive results when you farm in Nature’s image. In the last decade, with the addition of cover crops, and the belief that plants feed the soil, instead of soil feeding the plants, we have seen incredible results.

        http://amazingcarbon.com/PDF/JONES-FrontiersInAg-Unlock-the-secrets-in-the-soil_Summer%202015.pdf

        Awesome pic of you by the way!

        Additionally, there are huge implications for this transition. The petro-chemical industry is significant and touches many people and businesses. That it has never really been optimal but rather anti life is not that surprising as I’ve heard that the industry came out of the munitions and some chemical warfare industries. I’m sure those in the industry are smart enough to see the writing on the wall and I’m sure they are also responsible enough to transition to a natural life supporting way of business also.

        Cheers.

  2. Patrick says:

    I find your stance regarding Dr. Ingham problematic as you are asking for something which is beyond the capacity of microbiology: certainty of quantitative analysis regarding microbiological activity. There are simply too many tiny things for all of them to be empirically verified. This is the crux of your critique and inasmuch you present a straw argument of Dr. Ingham’s position and the work which she has accomplished. Absolute knowledge is oxymoron, and yet with imperfect knowledge we build skyscrapers, bridges, send men to the moon and back, replace human hearts, etc. Instead of focusing on “meta” analysis of scientific literature, I strongly recommend that you peer review the work of Dr. Ingham as it will give you a more informed basis for the analysis of her claims and accomplishments.

    • I am not asking for quantitative analysis. Dr, Ingham was selling the ability to teach people to do quantitative analysis. I was simply pointing out that it was at the very least misleading marketing.

      Dr. Ingham’s claims about things like the importance of the ratio of bacteria to fungi and the benefits of compost tea are not accepted by main stream science.

  3. johnh1955 says:

    I think it’s fairly obvious that we have a problem relaying cause and effect. One come away from Dr Ingram’s seminars thinking the microbes are the cause of good soil rather than the effect of it and geology and climate play a larder role than she ever mentions. It’s like saying the desert is a desert because nothing lives there but WHY does nothing (or not much) live there? Because the environment is hostile to most of what we want to grow. Adding microbes will not help and it’s obvious. But it’s not obvious to housewives that adding microbes to your garden might not help anything but changing the climate and soil structure and fertility will and the increased biomass will be the signs of it and the above ground plants are a part of that biomass. We just have quit taking from the soil without returning what it needs to maintain the system. This is the model of Joel Salatin at Polyface Farms and he never talks about needing a microscope to asses the soil microbes.

    • Karl Aldinger says:

      Through deforestation, Rome helped create the deserts of North Africa. Restoring it is a long slow process, but deserts are not always deserts because nature made it that way. When we perform agriculture on land, we change it and the soil dramatically. Without plants to support the microbioms in the soil, it dies. Monoculture also stresses the soil, and our efforts to maintain a monoculture through manipulation of the soil with inorganic material, eventually leads to a killing of the soil microbioms, (the dustbowl). We’ve understood for hundreds (perhaps thousands in some cultures) of years that soil is fragile if we mistreat it. We are only now getting down to the science of understanding both plant nutrients AND how they are actually made available to plants (through the micorbioms). I believe you are giving too much credence to climate and not enough to the need for careful soil management or at least protection.

      It is a very strange theory that without plants, living soil dies, and without living soil, plants die. But it is also a fact. I do not believe that microbes are merely present in the soil because it is convenient for them. They are a necessary part of nature’s plant life, and that is the core of Dr. Ingham’s research. Yes you can try to grow plants with only water, sun, and a plant available concoction of minerals in non-living dirt, but it is not a sustainable way of farming or gardening.

  4. Jassa says:

    I’ve never even considered trying to identify all the different types of bacteria in the soil! Seems so absurd! The thing I’m concerned with is encouraging a wide variety of bacteria (through compost teas and worm teas, mostly.) Diversity of bacteria is what makes soil so strong and able to adapt to different temperatures, water levels, etc. In this Q&A from a scientist at the Soil Science Society of America: (http://www.goodsweetearth.com/yard–garden-blog/bacteria-in-soilis-it-harmful-in-humans):

    “The critical point is that the soil doesn’t contain just one type of bacteria or one set of abilities (enzymes). It’s also not full of pathogens, nor are all the bacteria in soil active all the time. Instead, soil activity changes with fluxes in moisture, temperature, and substrate input. In order to respond to an ever-changing array of inputs, the soil biology is biochemically (enzymatically) diverse in its ability to utilize foods and electron acceptors. This diversity gives soil its resilience.”

    I can’t imagine caring WHAT the bacteria actually are, only that they’re there, and there’s a enormous variety.

    • I agree, but Dr. Ingham and the food soil web followers do not. They want to control the diversity, and even modify depending on the type of plant they are trying to grow. You can find more on this in my review of the book Teaming with Microbes which will be published the first week of April 2016.

  5. Tim Auld says:

    Hi Robert,

    Having been through two of Dr. Ingham’s courses and other material, this reads like you don’t know what she’s on about. Why are you using an ambiguous marketing dot point to derail her work?

    Dr. Ingham does not teach identification of specific species of bacteria or other micro-organisms using light microscopes. She readily admits that it is difficult to do this and that most species don’t even have names. She does teach identification of different types, shapes and sizes of microbes. For example bacteria vs. fungi, cocci vs. rod, disease causing fungi vs. beneficial fungi, and aerobic vs. anaerobic bacteria. From this basis plus counting individuals in diluted samples, the estimation of diversity.

    • “ambiguous marketing dot point to derail her work?” – what about my post was ambiguous?? I am not trying to derail her work. I am trying to point out to the uninitiated that some of her advertised claims are not valid.

      Dr Ingham may not teach identification, but that is what she promotes in her marketing pieces. You say she does teach telling the difference between “disease causing fungi vs. beneficial fungi” How is that done without identifying them? Same for “aerobic vs. anaerobic bacteria” – you can’t tell the difference by looking at them with a microscope.

      So you are saying that you don’t need to identify them – but by counting numbers you can estimate ‘biodiversity’? Biodiversity is the “variety and variability of life”, which implies identification.

      Dr. Ingham does talk about trying to understand the biodiversity of the bacteria and fungi – to do this you need to be able identify them.

      • Tim Auld says:

        Hi Robert,

        The marketing dot point you chose as the basis of your argument is ambiguous, not your post. There are at least two meanings and you have taken a meaning that the author did not intend, apparently disingenuously. If you had taken the correct meaning (i.e. the course teaches you to identify major types and characteristics, and that these microbes as a collective can help your plants to thrive) your article would be very different. Now that you know the intended meaning, are you going to correct your post?

        Dr. Ingham is a world renounded microbiologist with at least 57 peer-reviewed scientific papers to her name (http://www.soilfoodweb.com/drInghams_cv.html). She produces a 6 DVD lecture series, a 2 DVD review series, and several how-to DVDs and audio CDs. She features in over 100 free YouTube videos. The only reasons I can think of that you chose an innocent marketing dot point to attack is that you are either lazy or have poor judgement. Are you now accusing her of false advertising?

        She teaches that disease causing fungi tend to be thin, lightly coloured or colourless, and have few or no septa (cross walls). Some spores can be identified, such as those of phytopthera spp. All things you can easily see with a light microscope. Yeasts (which produce root dissolving alcohol), indicating low oxygen conditions, can also be seen as they are large and have a characteristic nub where they divided.

        Anaerobic bacteria tend to form large fuzzy biofilms around organic matter (why counting anaerobic bacteria is impractical). You can also see large ciliates moving around them which are known to feed on anaerobic bacteria. Actinobacteria such as streptomyces common in compost heaps can be identified by the very thin strands. These are facultative: both aerobic and anaerobic, thriving in low oxygen conditions and inhibit mychorrhizal fungi. Kind of interesting to know, right? With some staining you can tell if a root is infected with a mychorrhizal fungi; a very beneficial interaction as you would know.

        You can tell the difference between bacterial feeding, fungal feeding, root feeding, predatory and omnivorous nematodes by their mouth parts and organ structure. See an increase in different kinds and you might be on the right track. Use a new pesticide and see a sudden drop in variety or an increase in root feeders and perhaps you shouldn’t use it again.

        You don’t need to identify species to detect changes in biodiversity. Differences in size, shape, colour and behavior indicate that different species are present. It’s a process of forming a benchmark and then tracking changes over time. Precision is not needed as long as the method is consistent.

        Consider it to be like bird watching when you’re unable to identify the species. On your first trip you count 15 different looking birds. On the next trip you spot 30 different birds and 2 times the number of individuals. It would appear the biodiversity has increased. Of couse there will be fluctuations based on the season, but over time you can identify trends. If suddenly you only see 3 different birds it’s likely something went wrong and species have died off.

        • If I was lazy – I would not have bothered to write the post!

          Except for clarifying the statement that when Dr. Ingham says ‘identify’ she does not mean identify, you have provided no other example of something in the post which is incorrect.

          You say “You can also see large ciliates moving around them which are known to feed on anaerobic bacteria.” – that is true, and yes it is interesting. But how does a gardener convert this observation into practicable garden action items. There is a common thread between your comments, those of David’s and the information provided by Dr. Ingham – interesting stuff that never leads to action items. I never disputed that a microscope can be fun or even educational. That does not make it useful in the garden.

          Your comparison of 15 different birds is a ridiculous one. I can see differences in the 15 birds – I can’t see differences in the 5,000 different oblong shaped bacteria. You will learn nothing about species diversity. Even if you see some changes over time – it tells you nothing about how to change your gardening practices.

          I don’t think Dr. Ingham false advertises – but she is also not very clear about her program. ‘Misleading’ is a better word, and I do plan to update the post once I have all of the information I need to do it properly.

      • Gary L Newton says:

        I’ve been looking through microscopes for about 30 years and my initial reaction is usually “what the hell”

    • Geoff says:

      Your piece on soil microbes is spot on. The idea that adding microbes into the soil will have the benefits that are presented by adherents of the Soil Food Web is little more than wishful thinking. We do know that adding composts will add microbes and that different composts have different types and quantities of microbes but when you read the research (for example studies by Hoitink et al. at Ohio State University) you will understand the limitations of this approach. We can only make significant and lasting changes to the soil mirco-flora by making changes to the soil environment in addition to adding the microbes. Just adding “bug”s does very little.

      As you stated; adding composts can increase microbial populations and microbial activity (both fungal and bacterial). Much of the increase can potentially reduce some soil borne root diseases but claims that go beyond that are going too far and misleading.

      • The benefits of adding microbes to soil is not part of this post – but it is a very critical part of soil wood web process. And as you say – the whole concept is flawed. There is no scientific evidence that adding microbes to soil will have significant effect.

        I am currently writing a critical review of Teaming With Microbes, which is a summary of the soil wood web process, and will write more on this topic shortly.

        • johnh1955 says:

          That would be Soil FOOD Web not soil WOOD web. Your spell checker missed it a few times.

          I agree with the premise of this original post. Ive been a professional landscaper for 45 year and I have been looking into the ideas promoted by the Soil Food Web and I bought and use a microscope but the idea that you can identify specific microbes and determine soil health by it is not convincing. How can Dr. Ingham teach a young unsuspecting girl that’s all excited about this concept to actually identify organisms in a meaningful way that’s worth paying thousands of dollars for unless it’s just to give them a vocabulary that makes them sound like an expert. You don’t need to spend thousands of dollars to learn to make compost or compost tea or raise composting worms. But is you want to be able to say you are CERTIFIED so you can charge more money for your services of spraying tea or spreading shit (compost) on your clients landscapes then I guess that’s the real benefit. The microbes that are thriving in the tea after you add kelp and fish hydrolysate and molasses are not necessarily what will thrive once you apply this to your clients soil because the conditions are not the same. Just add the kelp and fish and whatever else meal you need based on what your soil and plants need and the appropriate microbes will do their job on it to make the nutrients available. Mulching is natural and helps maintain soil moisture, balance temps and return nutrients. You don’t need a microscope to know this, just start growing plants and the plants will tell you what they need. But it is fun looking at compost extract under a microscope. The longer you “brew” it and keep feeding it the more interesting organisms colonize it which make for fun photography as well. Seeing a rotifer that does not act like a rotifier swimming around at high speed rather than using his foot makes you wander what exact species it is because you never saw one like that before and gee, where did it come from? All fun but pretty much useless information in the real world of gardening. But if you’re smart and with a good vocabulary you can capture the imaginations of a lot of customers to your nursery with your free seminars and sell lots of vermicompost.

          So I can say this for sure . . . it’s good for business :o)

    • Geoff says:

      I am sorry to say as a person with training in soil microbiology and mycology, it is very difficult if not impossible to distinguish much at all useful from the examination of soil using a microscope. You can not rarely identify species of bacteria and fungi by looking at the soil. However even if you could make identifications that information would be of limited value in assessing the state of the soil. The issue is not what microbes are present in the soil but what are the microbes doing. Microbes of a variety of different types can be found and isolated from the soil but may in fact be inactive. Some bacteria for example can grow and thrive in both anaerobic and aerobic conditions. Do you really believe that your visual observations are able to distinguish which metabolic pathways are being used as you look through your microscope? Staining can only distinguish live and dead cells but tells us nothing about their activity.

      Get back to the basics; for most of us trying to grow plants in our gardens and landscapes the soil conditions that matter the most are the physical properties such as soil texture, porosity, and compaction. The work by Dr. Ingham is a distraction from what is most important and is not supported by scientific studies and independent researchers. The issue is not that so much of what is advocated by Dr. Ingham is wrong it is that it pulls the focus away from the real valuable and useful information.

      • Tim Auld says:

        Hi Geoff,

        I’ve already said that it’s not about identifying species (or metabolic pathways, for that matter), but diversity. Why? Because if you have a high biodiversity there will be structure being created, pathogens being suppressed and nutrients cycling in most conditions. Of course you are going to underestimate the actual diversity because many microbes look the same, but changes is visual diversity follow changes in species diversity. How could it not?

        For the farmer or gardener trying to improve their soil it’s about identifying changes and getting clues about what’s happening to inform decision making. If you are spending significant sums of money don’t you think it’s valuable to have some idea what your treatments are doing to the biology that builds the structure you point out is so important, breaks up the compaction, and which gather and cycles the nutrients your plants need? Otherwise it seems you are flying blind and have to rely on macro observations or advice from a soil chemistry lab.

        Dr. Ingham has documented many case studies showing the dramatic effect the proper application of her methods can achieve. I am interested in hearing more about these studies that don’t support her research. I have come across some but nothing conclusive. Mostly just opinions such as Roberts.

        Also I am interested to hear what you consider to be real and useful information in comparison.

        • Lee Reich says:

          Yes, “Dr. Ingham has documented many case studies showing the dramatic effect the proper application of her methods can achieve.” Generally, there has been little or no documentation in well-designed studies of Dr. Ingham’s methods by anyone other than Dr. Ingaham. Plenty of well-designed studies, on the other hand, discount her methods.

          • Shane says:

            Hi there. Would you be able to link to some?

          • leereich says:

            For a good summary: Scheuerell, S. and W. Mahaffee. 2002. Compost tea: Principles and prospects for plant disease control. Compost Science and Utilization 10(4):313-338.

          • Shane says:

            I don’t think that paper says what you seem to think it says. In a nutshell it’s an analysis of varying previous research papers across a range of subjects and time periods and thus is a bit of a patchwork of ideas and data that concludes by saying that compost tea holds promise and can demonstrate some efficacy in providing disease resistance to pathogens, but we need to research more.. which does nothing to contradict what Dr Ingham teaches as far as I can see.

  6. David says:

    Dear Robert Pavlis,

    Hi, I wanted to address your article about soil bacteria point by point. Thank you for writing such an interesting blog, we are all on the same side here as gardeners, growers and farmers so I just wanted to provide my alternative point of view in hopes that we may eventually see things eye to eye. I look forward to hearing your response.

    #1 “The one I’d like to discuss today deals with the idea that you can figure out which type of bacteria you have. Armed with this information, you can then manage the populations to increase the ones that are most beneficial for your plants.”

    -I don’t think anyone is saying you can figure out exactly what kind of bacteria is in the soil. Soil food web analysis is not about identifying specific bacterial species or fungal species. The point of using a microscope is simply to see if you are missing any of the primary species responsible for nutrient cycling and to compare their relative abundance.

    #2 “Unfortunately, Dr. Ingham then takes these ideas to a ridiculous extreme. She recommends gardeners should look at the microbes with a microscope, and with this device, they will be able to identify the various bacteria in soil.”

    -I’m interested where you got this idea from because Dr. Ingham does not promote using the microscope for identifying specific bacterial species at all. I’m not quite sure how someone could interpret her work in that way.

    #3 “Once you know which bacteria you have in your soil you can take steps to manage the herd, and increase the right ones which would make the growing conditions more favorable for your plants. She goes on to suggest that different plants need different populations of bacteria and gardeners can learn to customize their soil.”

    -The idea of a microbial herd does not refer to the bacteria. The bacteria and fungi are like the grass. The protozoa and nematodes are the herd that grazes the grass. This grazing of bacteria and fungi by protozoa and nematodes is how plant nutrients are released in an available form.
    It is possible to identify whether a material will be preferentially decomposed by bacteria or fungi based on its carbon to nitrogen content. Therefore one can adjust the bacterial to fungal ratios in the soil by adjusting the C:N ratios of the litter layer. Litter with a high ratio of C:N like woodchips will result in fungal dominance, something like fresh grass clippings would result in bacterial dominance. This is something anyone can easily test for themselves with a microscope.

    #4 “Here is a quote from the advertisement for one of her courses where a full day is dedicated to identifying microbes: “Get the necessary training to identify the bacteria, fungi, protozoa, and nematodes that drive the health and well being of our plants” (ref 1, Soil Foodweb with Dr. Elaine Ingham).”

    -I can see how one might interpret this to mean species level identification. The word identification is used in this context more like the word assess. They mean to say that you can get training which will enable you to personally evaluate soil microorganism communities. The main focus is always on the interactions between these organisms and what they accomplish as a whole.

    #5 “What I have a problem with is the idea that anyone can control this situation in a quantitative way. To do this you need to be able to identify the current bacterial types that you have, and then influence their populations to make them more suitable for you plants.”

    -Soil food web analysis can tell you if you’re missing any key groups that may have been killed off by poor management. The protocol works like this. If you are missing nematodes for example, you can test compost, or even soil from a different location to ascertain whether the missing nematodes are present in the new material. If it does contain the nematodes, then the material is spread in the field. After that point, one can do a microscopic soil test once per year or less to monitor the persistence of the new species in the field.

    #6 “The bottom line is that no one is able to identify bacteria species by looking at a soil sample. If the experts can’t do it, gardeners can’t do it – even if they take Dr. Ingham’s course.”

    -It’s misleading to suggest that the course offered by Dr. Ingham claims to do that. Identifying the individual species is not the overall goal of her method.

    #7 “You can’t differentiate aerobic from anaerobic bacteria, based on physical appearance. You also can’t differentiate between beneficial and pathogenic bacteria. Identifying a bacteria as belonging to one or the other of these classes is critical to Dr. Ingham’s methods for the management of soil bacteria, and especially for the creation of compost tea.”

    -It is correct that you cannot differentiate between species of bacteria using a microscope. It is incorrect that this “is critical to Dr. Ingham’s methods for the management of soil bacteria.” Bacteria are just one group of organisms in the soil food web. Dr. Ingham’s methods are designed to teach people to recognize the difference between bacteria, fungi, protozoa and nematodes. From this understanding people can see if their soil is missing any one of those essential groups and work to restore those organisms using whatever techniques are the most economical. Compost tea is one option that under certain conditions is the best option. In the majority of cases Dr. Ingham herself recommends applying solid compost at a rate of ½ ton to 1 ton per acre.

    #8 “You can count the number of bacteria you see, but I don’t know how accurate that is for a soil sample. The average gardener can learn very little about the bacteria in soil by looking at a soil sample under a microscope.”

    -Counting bacteria, fungi, protozoa and nematodes can be used to learn quite a bit of information about soil. When soil is completely missing nematodes or another key organism, Dr. Ingham would call that “out of whack”. To get soil ”in whack” we simply have to add nematodes or whatever is missing so that there is no longer a missing link in the food web or an imbalance in the bacterial to fungal ratio. I have spent many hours looking at dead soil that contained literally no fungi, protozoa or nematodes and then watched that soil come to life after applying compost and the right C:N ratio mulching materials. My own personal experience with the microscope has deepened my appreciation of the natural world beyond words.

    # 9 “Here is what one of them says “Complete Food Web Test (done by SFWNY) – Quantifies total and active bacteria, total and active fungi, and presence/absence of protozoa” , ref 5 Soil Foodweb Inc – Identifying Organisms. Your results will give you 4 numbers plus a yes/no for protozoa! Remember this is a ‘complete’ test, but it does not provide any information about the identification of bacteria. Odd – maybe the testing lab never took Dr. Ingham’s course?? “
    “So even the recommended professional labs don’t try to identify species, aerobic vs anaerobic, or even beneficial vs pathogenic. Why? It’s too complicated.”

    -The reason they don’t provide any information about the specific identification of bacteria is because that is not a part of soil food web analysis. They do go further than most by distinguishing between total and active bacteria, as well as total and active fungi.
    Quote from different testing company affiliated with Dr. Ingham called Earthfort, “Except where noted, these tests do not identify specific organisms. In other words, we measure the Biomass of Total Populations in general categories of the functional groups.” Check out the test descriptions. This lab also combines the soil food web results with soil chemistry testing in their full report.
    http://earthfort.com/lab-services/test-descriptions-2/

    # 10 “The idea that someone can take a light microscope and find out critical information about their soil bacteria is ridiculous. You can certainly see bacteria, and you might be able to count some of them. That information is not very useful.”

    -The soil food web report can provide an estimate of plant available N in pounds per acre released during the growing season by looking at data which includes the numbers of bacteria, fungi, protozoa and nematodes. Knowing how many pounds of plant available N are released throughout the growing season is an important metric for many farmers. The ratio of ciliates to nematodes is also an indicator of oxygen levels. Ciliate populations are especially high in anaerobic conditions while nematodes are higher in aerobic conditions.
    http://articles.extension.org/pages/24726/soil-nematodes-in-organic-farming-systems

    # 11 “Even if you could get the information, what would you do with it? I don’t see how you would know which bacteria you should grow for each of your plants? No such table exists. How does this change for each plant you own? Nobody knows. We don’t even know which bacteria live in your soil!”

    -Some plants prefer totally fungally dominated soil, some prefer totally bacterially dominated soil, and there is a whole spectrum in between. Over time, fungally dominated soils tend to lower the p.h .into the acidic range because fungi normally produce more powerful organic acids than bacteria.
    More fungi instead of bacteria also results in lower earthworm numbers over time, but higher microarthropod populations. This is why we find more earthworms in grasslands than under woody forest litter and why we find more microarthropods in the forests than in the grasslands.
    The general rule is that perennial plants prefer a fungally dominated environment and annuals prefer a more balanced or bacterial environment, with some exceptions.

    http://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/soils/health/biology/?cid=nrcs142p2_053865

    # 12 Except for counting bacteria, a microscope will not help you to qualify your compost tea herd.

    -Dr. Ingham teaches people to do what is called a qualitative assessment. Bacteria, fungi, protozoa and nematodes are counted and can be used to calculate the rate of nutrient cycling. The rate at which unavailable nutrients become available nutrients is highly dependent on the temperature, moisture and the specific number of microbial predators. http://ohioline.osu.edu/factsheet/SAG-16

    Dr. Ingham’s wrote the standard operating procedures for the USDA for assessing microbial populations and community dynamics for these microorganisms in addition to publishing nearly 50 peer reviewed scientific articles in the field. http://www.soilfoodweb.com/drInghams_cv.html

    Best regards,
    David

    • Thank you for the detailed reply.
      1) One of your key points is that Dr, Ingham does not promote the idea of using a microscope to identify microbes, and you are “not quite sure how someone could interpret her work in that way”. Everything I have ever read about your course, and her videos promote this idea. The quote I added “Get the necessary training to identify the bacteria, fungi, protozoa, and nematodes that drive the health and well being of our plants” (ref 1, Soil Foodweb with Dr. Elaine Ingham).” clearly talks about identifying bacteria.

      Counting all bacteria would include those that are NOT driving the health and well being of plants – but she clearly excludes these. In that case one would need to be able to identify one type from the other – not just count all of them.

      I have no reason to doubt your statement that what she actually means to say is to ‘count’ the total number of bacteria. It is more believable. I guess this is a case of false advertising – perhaps one that is not intentional.
      If the requirement is only to count the number of bacteria, fungi, protozoa, nematodes, then it leaves two important questions:
      (a) How accurate are the counts from graduating students who are gardeners without prior microbiology training? Can someone be trained to do this counting properly in a day? A report from a third party would be needed to confirm this.
      (b) How accurate is the counting by professionals?

      2) Replacing the missing organism. In several of your points you say that if one organism class – say nematodes, is missing, you can get another source of compost that contains the organism and spread it on the soil solving the problem. I see two issues with this idea. Firstly, garden soil is never deficient in one of the organism classes. There are always nematodes around – same for bacteria, fungi and protozoa. Numbers can be higher or lower, but except in extreme cases it is not zero.
      The second problem is that if they are not there or in low numbers, it means the soil or its inhabitants are hostile to the organism preventing it from growing and adding more will not likely change the number found in the soil.

      How do I know that I am not importing a non-native nematode, or a pest nematode? Ontario and a good part of Eastern US has a major garlic nematode problem – there are very few nematode free sources of garlic here. If my nematode numbers are low, and I being them into my garden I will also have the problem. Right now I don’t because my strain is 20 years old and has never grown in soil with garlic nematodes. If all I am doing is counting them – and not identifying them – I could be bringing a big problem to my garden.

      3) Let’s assume that one only needs to count bacteria, fungi, protozoa, nematodes to make Dr. Ingham’s system work, and that, I, a gardener, can count the organisms accurately enough for the system to work. I have my numbers. What now? Where do I go to figure out what I do with these numbers?
      You have said a lot of complicated, but vague, things one could do, and you have given several references that also give high level ideas. This is all very nice, but theoretical. Gardeners are practicable people who now need clear instructions on what to do next. Where do they get them? How do I convert my counts into actionable steps?

      • David says:

        Dear Robert Pavlis,

        Thank you for your questions, I’ve reposted the questions followed by my answers here. I can only provide so much information before recommending you take Dr. Ingham’s course or search the scholarly literature for answers, but I have tried my best here to briefly address your concerns.

        1. “a. How accurate are the counts from graduating students who are gardeners without prior microbiology training? Can someone be trained to do this counting properly in a day? A report from a third party would be needed to confirm this.
        b. How accurate is the counting by professionals?”

        -Almost everyone has used a microscope at some point in school, and anyone, even children, can learn to do this in a day. Counting the exact number of bacteria and measuring hyphal diameters in order to convert into biomass is not something everyone can be trained to do, neither is distinguishing active from total bacteria and fungi. The professionals provide these services in addition to information about whether nematodes are bacterial feeding, fungal feeding, predatory, or root feeding. Professional labs can also sometimes test for mycorrhizal colonization as well.

        $260.00 Microscope recommended by SFI
        http://www.microscopenet.com/omax-40x400x-binocular-compound-siedentopf-microscope-soil-microscopy-p-10727.html

        2. “Replacing the missing organism. In several of your points you say that if one organism class – say nematodes, is missing, you can get another source of compost that contains the organism and spread it on the soil solving the problem. I see two issues with this idea. Firstly, garden soil is never deficient in one of the organism classes. There are always nematodes around – same for bacteria, fungi and protozoa. Numbers can be higher or lower, but except in extreme cases it is not zero.

        The second problem is that if they are not there or in low numbers, it means the soil or its inhabitants are hostile to the organism preventing it from growing and adding more will not likely change the number found in the soil”

        – I agree most garden soil does probably contain a healthy soil food web already. Adding more bacteria, fungi, protozoa and nematodes to soil that already has them is totally pointless and if the numbers are low simply adding more mulch is often all that it takes to make them rise again. This is something I wish more people who brew compost tea understood as I routinely find them applying tea on a weekly or monthly basis to soil that often doesn’t even have mulch.

        Soil food webs are extremely stable and it takes serious disturbance to completely lose a key group like nematodes. Tragically, on many acres of agricultural land, excess tillage has depleted organic matter to levels less than one percent. In excess of 4 feet of soil has been lost from some areas. The absence of organic matter combined with excessive applications of fungicides, pesticides, herbicides, fertilizer and salinated groundwater have left acres of agricultural land severely degraded. Soil organisms need organic matter and when it reaches a low enough level the soil food web dies off.

        When farmers, or gardeners, irrigate land that was previously dry it opens up the opportunity for not just more plant production, but more microbial life. Within the boundaries of our ability to change conditions with irrigation and stop damaging soil with toxic management practices there is a huge opportunity for introducing biology. In most cases these species will return to the soil simply if the conditions which resulted in their absence are ameliorated, but this is an unpredictable process and in some cases takes years or decades. In semi-arid or arid regions where there are few reservoirs of native organisms the soil food web is even more fragile and slower to recover. Organisms also do not usually return as a complete group, but slowly one species at a time. Important, higher level species like predatory nematodes can be especially slow to return after disturbance. Professional farmers just can’t afford to wait around for these organisms to come back and miss out on ecosystem services. The application of organisms is simply our way of speeding up what would naturally happen on its own so that growers can be more successful.

        In other cases, like indoors or on patios, soil is permanently isolated from reservoirs of wild organisms and may never acquire a complete soil food web because of its physical isolation. Commercial potting soils and bagged composts often have no detectable fungi, protozoa, nematodes, arthropods or earthworms because of the extremely hot/cold or dry conditions the bags are stored in. I always advocate people try to work with their garden soil in containers and make their own compost before buying expensive, dead commercial potting soil or compost.

        3. “How do I know that I am not importing a non-native nematode, or a pest nematode? Ontario and a good part of Eastern US has a major garlic nematode problem – there are very few nematode free sources of garlic here. If my nematode numbers are low, and I being them into my garden I will also have the problem. Right now I don’t because my strain is 20 years old and has never grown in soil with garlic nematodes. If all I am doing is counting them – and not identifying them – I could be bringing a big problem to my garden.”

        – In specific reference to nematodes, the professional laboratories can accurately report whether the nematodes in your compost are bacterial feeding, fungal feeding, predatory, or plant parasitic.

        The soil food web in a healthy aerobic compost pile selects against harmful organisms using an array of mechanisms. There are many scientific articles on specific mechanisms that are responsible for the destruction of specific organisms. The link below is one example that talks about how springtails eat the specific garlic nematodes you mentioned. Springtails are a common inhabitant of healthy soil food webs.

        Collembola Predation on Nematodes, Agric. 1970 Vol. 1 No. 3 pp. 1-12

        http://www.cabdirect.org/abstracts/19740517652.html

        http://www.cabdirect.org/abstracts/19722000404.html

        4. “Let’s assume that one only needs to count bacteria, fungi, protozoa, nematodes to make Dr. Ingham’s system work, and that, I, a gardener, can count the organisms accurately enough for the system to work. I have my numbers. What now? Where do I go to figure out what I do with these numbers?
        You have said a lot of complicated, but vague, things one could do, and you have given several references that also give high level ideas. This is all very nice, but theoretical. Gardeners are practicable people who now need clear instructions on what to do next. Where do they get them? How do I convert my counts into actionable steps?”

        -Once you get your numbers you can use them to determine what organisms you might need to add. The professional labs can also use these numbers to recommend if you should add fertilizer or not. Aside from the soil test itself, learning about the soil food web can help gardeners reach more informed answers to common questions like what type of mulch to use, what plants will grow well together and why certain weeds seem to favor certain soils. Healthy soil food webs help prevent disease, pest infestations and weeds.
        Growers who normally follow a program of tilling the soil and then applying fertilizers, pesticides and fungicides can in many cases ultimately eliminate all of those practices.

        These issues are of greater importance for professionals who as Dr. Ingham says, “Have their feet to the fire”. Extensive soil testing is not required for the average hobby gardener. However, when one makes their livelihood from the soil it is worth knowing about things like the soil food web, total soil carbon, and cation exchange capacity. I acknowledge these topics might not interest everyone, but they are highly important to many farmers and ranchers.

        For gardeners looking for a place to start, the book “Teaming with Microbes, A Gardeners Guide to the Soil Food Web” is a great introduction to the subject for hobby gardeners and professionals alike. Although some may disregard the book for promoting compost tea, the sections on the soil food web organisms, compost preparation and mulches are indisputably accurate. The book also gives the general guidelines that most gardeners are looking for when it comes to plant care and a concise list of rules for gardeners in the back of the book based on an understanding of the soil food web.

        I admire your skepticism. The agricultural world is full of bunk products and it is only by asking questions that we can protect ourselves. I only ask that you keep an open mind about what the soil food web is capable of in its entirety.

        Best Regards,

        -David

        • I asked how accurate are counts by gardeners following training. You say “Counting the exact number of bacteria and measuring hyphal diameters in order to convert into biomass is not something everyone can be trained to do” – I agree. If the accuracy is not high enough to be of much use – then it does not make sense for a gardener to take this course with the aim of improving their soil.

          You said “I agree most garden soil does probably contain a healthy soil food web already. Adding more bacteria, fungi, protozoa and nematodes to soil that already has them is totally pointless and if the numbers are low simply adding more mulch is often all that it takes to make them rise again.” I agree totally and said so in this post and others. The micros are already in the garden soil. Add compost and organic material to keep them happy.

          With respect to my nematode comment you said “In specific reference to nematodes, the professional laboratories can accurately report whether the nematodes in your compost are bacterial feeding, fungal feeding, predatory, or plant parasitic”. I am not sure this is correct, but it is not important. We have already concluded that a gardener who is trained using Dr. Ingrams course will not be able to do this. So a gardener armed with their microscope could quite easily import pathogenic nematodes.

          My last point was, if a gardener had the numbers of various classes of microbes – how do they use this data. You were not able to provide a simple answer. And you are quite correct – there is no simple answer. Simply having these numbers will not guide the gardener to a better garden unless they become soil scientists. Gardeners do not want to do that – they want and need a simple answer. As long as the soil food web program can not do that – then my conclusion is quite valid. “The average gardener can learn very little about the bacteria in soil by looking at a soil sample under a microscope.”

          Some of your points are correct, and for farmers and soil scientists they can be used productively. My comments are for gardeners.

  7. Joan smith says:

    I agree and disagree. I remember in my microbiology course, doing a battery of tests to identify our test organisms. We all worked very hard and could do a gram stain in our sleep by the end of the course. There was one student who didn’t do his work and those of us who did could tell him what his organisms were by just looking at the gram stain. Of course there were only a few organisms to chose from and the soil would be much more complicated. But I think if you routinely looked at your soil microscopically, you might pick up changes and this info may be useful at some point. I bet the soil microorganisms in the soil also change with the seasons. I would love to be able to ID cotton root rot which I think I may have in my soil. I think soil microbiology would be a great course for farmers and interested gardeners and would increase our understanding and knowledge. Wouldn’t it be interesting to compare slides of soil before amending and after and then every month through the growing season to see if there are changes? And maybe compare it to a control bed? I never took her course because I thought, how would I know what I was looking at. But I think a college course on soil microbiology and a microscope could improve our understanding of the soil.

    • A college course in microbiology and a 1 day training for someone with no experience are two different things. It is true that “a microscope could improve our understanding of the soil” but will it really allow a gardener to know which are the best steps to improving their soil?

  8. Patty says:

    I read in a good book about soil (now forgotten which one) that one way to increase the bacteria you want in your soil is to mulch with the products that garden area creates. So in a very simplistic way, if I want to enhance the soil bacteria in my woodland area I would mulch with pine needles, leaves, and other tree and shrub debris. Alternately if I am growing a vegetable garden or ornamental flowers I would be better off mulching with garden and food waste. I would like to know your thoughts on this.

    • Makes sense to a certain extent. I am sure that leaving maple leaves on the forest floor of a maple forest will encourage the increase in natural bacteria.

      However, a garden is not a natural place. You can’t extend this logic to a garden, like a vegetable garden. Any bacteria present are no longer natural populations – they have been altered by the manure or compost you have been adding, to say nothing of the plants you are growing. Adding vegetable scraps makes no more sense than adding hosta leaves. Both will increase populations that are present, but you don’t know which are being increased.

      Also, bacteria are that specific. They are probably generalists that will start to degrade any organic matter that is next to them – maple leaf, hosta leaf or old tomato – it is all the same.

  9. Great post. Back in the mid 90’s the soils lab that I was working in got asked to do some of the testing to determine bacteria counts. We declined the work.

  10. rogerbrook says:

    You are an excellent teacher Robert!
    It’s a bit of a paradox to gardeners who seek to educate themselves. Bacteria are fundamental to soil life and yet their precise makeup is unknown and ever changing, the gardener can do little about them and in most cases it does not matter.

    • Thanks Roger.

      It is surprising that so many talk about bacteria in soil, and yet we know so little. All we can really do is leave the soil alone as much as possible and add organics – just as nature would do. Then hope for the best.

  11. So many folks take some science, distort it a bit, and then convert it into bafflegab in the hope of making a quick buck – you could have written the same column about “probiotic” gut microbes.

  12. Lee Reich says:

    Excellent points! Another limitation of Dr. Ingham’s claims is her overlooking that when you extract bacteria from soil or compost, you’re not seeing the spectrum and numbers of organisms in the soil or compost. What you are seeing is the spectrum and numbers of organisms that you extracted. There is a difference.

    • Good point. Gardeners need to keep things simple.

      • F.a Odendaal says:

        What qualifications do you have?

        • I am a chemist, biochemist, and life long gardener. I now study gardening myths and the science behind them.

          • Shane says:

            So (respectfully) no experience or expertise in biology, soil ecology or microbiology? I am not sure you understand what Dr Ingham is teaching deeply enough to be in a position to fairly or responsibly critique it, to be completely honest.
            Maybe take her course, or attend a workshop or even pick up this knowledge form another source (like the book Teaming With Microbes for example) and try applying this knowledge and see for yourself.

          • I have studied a lot of Dr. Ingham’s writings, including the Teaming With Microbes which I have reviewed in detail here : http://www.gardenmyths.com/teaming-with-microbes-close-look-part-one/

            Much of the information I present comes from other scholars who understand the science in specific areas better than I do. My job is to take their work and make it available to the public. Many of Dr. Inghams ideas are not supported by science, nor are they accepted by the scientific community. She has also not published her research work in this area – there must be a reason why.

  13. John says:

    Another good article; thank you. I agree completely. Another good reference that I found deeply insightful on this topic is: Soil Microorganisms and Higher Plants – N.A. Krasilnikov (1958)

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