Humus Debate --- Reborn

Discussion in 'Organic Lawn Care' started by JDUtah, Jun 22, 2008.

  1. JDUtah

    JDUtah LawnSite Silver Member
    from UT
    Posts: 2,636

    This is an attempt to restore an interesting debate that was deleted about the subject of Humus. I have contacted a moderator and asked if he could send me the posts that were deleted so I can use them as a resource to restore the debate.

    The debate has surfaced on other threads in the forum as well and I will attempt, after posting the original subject matters, to pull the information from those into this thread. The goal is to have this thread be an exhaustive resource (and links to resources) about the subject of Humus. I hope the heat of the moment is not diluted to the point it is not as interesting, and I also hope the thread will not address so many different subjects of humus that it becomes hard to follow. Time will tell. :)

    I have not heard a response from the moderator yet and will do my best to resurrect the points from memory. I will also try to leave out points that were not discussed but that have been researched and learned after the debate started. This may be a lost cause lol. If I do receive the original transcript I will follow up and add or correct any information as needed. Anyone that followed the debate is welcome to pipe in about it as well. And anyone else that wants to join in… welcome!


    The debate started in a thread where someone was asking where to buy gypsum powder to use in an attempt to break apart heavy clay.

    It was brought up that humus could be used instead of the gypsum powder, and that post suggested that humus was only available through one manufacturing company.

    I thought humus was available in any compost pile. Hence, find any old compost pile and you have your source of humus.

    Compost is not humus! Humus has no caloric value, and compost does. Humus contains Mycorrhizae and is made by them. (Lot’s of other arguments that I can’t remember)

    Ok, it looks like we are going to have to dissect that and zero in on definitions so we may be more accurate.

    Compost: a mixture of various decaying organic substances, as dead leaves or manure, used for fertilizing soil.

    Compost piles rely on the beneficial microbes that your are referring to as well. They heat up because the microbes are eating the organic matter in the pile and their metabolism releases heat. Eventually the temperature of the pile cools. This happens because the microbes have eaten the organic matter and have since died off.

    So according to our definition of compost, compost is the pile AS it is decaying. Humus is what is left after it is done.

    No, compost is only .004% humus!

    I do not believe that. Do you mind referring me to the source that you got that number?

    No source was posted.

    Hence I was left to find information on my own. In searching I found an interesting article on humus.

    I still do not believe the things you are saying about compost & humus. Here is the best definition I found of humus (referring to the article)
    “Humus is the end result of organic matter decomposition and recomposition by microbes. When fresh, undecomposed organic matter (green manures, animal manures, crop residues) is added to soil or placed in a compost pile, a rapid multiplication of soil microorganisms takes place. Certain microbes (bacteria, fungi, and actinomycetes) break this raw organic matter down into smaller particles (gums, waxes, lignins) resistant to further decay and simple organic compounds (sugars, amino acids) that are water soluble. Following the breakdown phase, a second group of microbes bind these materials together, especially lignins and microbial biomass, into more stable humic substances (fulvic acid, humic acid, humins) in the buildup phase.
    The physical, chemical, and biological transfomation of raw organic matter into a complex humic substance is known as humification. Friable humus (also known as effective humus or nutritive humus), which supplies slow-release nutrients over a period of weeks or months, is a short-chain humic compound. Stable humus (also known as permanent humus), which has a half-life of years and may be viewed as the soil humus bank, is a long-chain humic compound.”

    I thought humus was the most broken down form of organic matter. I did not realize that it had to be re-built. Interesting. However this article even states that their requirements for their finished compost is 50-80% humus, not the .004% claimed! (the ‘advertised’ product claims 94%? humus)
    Another argument made by the humus advocate was that it would take over 100 years for a property to create enough humus to cover 1” of the surface of the soil.

    The reply was… Let me continually harvest all the organic matter from the same plot of land, compost it and re-spread it taking into account plants using the humus for food, leeching, erosion, and other factors of degradation and it see if it wouldn’t take me 100 years to create enough humus to cover the same 1”.

    By this time I began to feel bad that the post had been hijacked and referred back to the original question… Where can I get Gypsum powder to help with my clay problem?

    I replied, “the only distributor I found was in Australia. Hmm... But if it is to help break up the soil humus might help...
    The article also explains a little more clearly (at least to me anyway) how humus helps clay soils.


    When conditions are optimal, microbes attach these long-chain humic compounds to the clay fraction, resulting in clay-humus crumb. These clay-humus crumbs are full of "nooks and crannies" which provide shelter for soil microorganisms. The enormous surface area and negative charge associated with clay-humus provides exchange sites for cations, and building soil humus is one of the few ways farmers can actually increase the cation exchange capacity (CEC) of soils. Clay-humus crumbs are highly desirable in building soil tilth and maintaining good soil structure and water holding capacity.


    So getting more humus in your soil will help to clump the clay and let it have more room for water retention, etc.

    It seems there are different ways you can do this...

    -Mix compost into the soil (or topdress if it is a lawn) and wait for nature to finish turning the OM into humus. (I still think the compost has more than .0004% humus though)

    -Speed up the process by applying a Compost tea full of microorganisms that will help the process along. You can hit and miss by random Compost Teas. Or you can determine a formula that has select microbes that are essential to this process. The people in the article i linked to apply a Compost Tea (they call it inoculent) that consists of 50 microbes that are selected for humufication. Interesting again. I want the list of those little guys!

    -Or you can buy the humus product directly from our friends ____ ____ and (till?) the humus in.

    Interesting to note however that the article I reference suggests that insoluble humus is most desirable as it will not leach with water like the soluble humus will.

    And that is where I would pick up the debate. Our new friend with ties to a humus manufacturing company needs to jump in and explain why their form (soluble humus) is better then the form the article says is best (insoluble humus)… I will drop my jaw in amazement if an article is actually referenced and in context!
  2. easygrass

    easygrass LawnSite Member
    Posts: 14

    thought I would put this here.

    I just wanted to post this info for everyone hope you enjoy this.

    HUMUS - Humus is defined as a brown to black complex variable of carbon containing compounds not recognized under a light microscope as possessing cellular organization in the form of plant and animal bodies. Humus is separated from the non-humic substances such as carbohydrates (a major fraction of soil carbon),fats, waxes, alkanes, peptides, amino acids, proteins, lipids, and organic acids by the fact that distinct chemical formulae can be written for these non-humic substances. Most small molecules of non-humic substances are rapidly degraded by microorganisms within the soil. In contrast soil humus is slow to decompose (Degrade) under natural soil conditions. When in combination with soil minerals soil humus can persist in the soil for several hundred years. Humus is the major soil organic matter component, making up 65% to 75% of the total. Humus assumes an important role as a fertility component of all soils, far in excess of the percentage contribution it makes to the total soil mass.
  3. ICT Bill

    ICT Bill LawnSite Platinum Member
    Posts: 4,115

    I am so pleased that you brought this up. I agree with this point, the story is much more complex than this

    Is it active or not?
    How was it deposited?

    Humus is what we want in our landscape, lawn and field

    Humus is??? organic matter that is balanced, maybe

    It is the fuel that makes the engine run, I think

    Humus is the end result of good inputs, or bad inputs over time

    Humus happens.......... eventually
  4. treegal1

    treegal1 LawnSite Gold Member
    Posts: 3,911

    OK this time I want you all to get me strait on this HUMUS thing........

    the more stable humus does not really add nutrients to the soil, only adds to the soil structure??? it binds???? with clay and silicone,,,,,,,eh...what??? soil microbes have a hard time "eating" stable humus??? is this like the long road to ADE

    I thought I had a handle on the humus thing, is worm humus stable or is it open to further decomposition???

    wish kiril would hit us with some paper, maybe some well viewed works.

    also would like a def of clay, just to keep us sand types on track
  5. DeepGreenLawn

    DeepGreenLawn LawnSite Silver Member
    Posts: 2,372


    Soil which is composed of very fine particles, usually silicates of aluminum and/or iron and magnesium. Clay soil impedes the flow of water, meaning it absorbs water slowly and then retains it for a long time. Wet clay soil is heavy and sticky, and tends to swell from the added moisture. When dry, clay soil shrinks and settles. The top layer can bake into a hard, concrete-like crust which cracks. Some plants have difficulty growing in clay soil because their seedlings or roots are unable to penetrate through hard, dry soil, or can be waterlogged in wet soil. Adding organic material to clay soil is an effective method of improving growing conditions.
  6. Smallaxe

    Smallaxe LawnSite Fanatic
    Posts: 10,081

    The balance of soils have 3 or 4 components. Sand, clay, silt, and/or OM. The perfect soil is 45%-55% sand, 35-45% clay, with the remaining 10% hopefully being silt and OM.
    The humus is the silt/OM part.

    I have always heard that the sun will degrade humus. Anyone know for fact if this is true or not?

    TG1 brings up an interesting correlation with ADE. To me I image both, humus and char to both be catalysts, rather than consumable. Increasing the CEC of the soil, by providing the site.
  7. jeffinsgf

    jeffinsgf LawnSite Senior Member
    Posts: 641

    I was under the impression that "humus" referred to the product of the naturally occurring decay process that happens in a forest compared to the accelerated decay process that happens in a man-made compost pile. Our state conservation department makes this distinction and suggests that woodland humus not be disturbed or harvested for use in gardens.

    Humus = slow
    Compost = fast

    DUSTYCEDAR LawnSite Fanatic
    from PA
    Posts: 5,137

    GREAT THREAD would humic acid help break up the clay?
  9. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

  10. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

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