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soil organic matter question

Discussion in 'Organic Lawn Care' started by ICT Bill, Nov 22, 2008.

  1. ICT Bill

    ICT Bill LawnSite Platinum Member
    Messages: 4,115

    We have been in trials this year with lots of franchises, was on a call from one this week. They used their typical program in the front yard and an organic one in the back yard, many sites

    They wanted to test efficacy and overall health, color, turf density and so on. They used an extracted, brewed and our instant compost tea. six applications were applied through the year. soil tests were taken at the beginning of the year and then again recently

    On the compost tea sites the only thing that was used was compost tea, no compost or other nutrients. On one site they used only compost and no teas, anyway.

    On the compost tea sites the CEC went up significantly on the compost only site it basically stayed the same. On our instant compost tea site the SOM went from 3.9 to 7.2, this was similar to all types of tea the SOM almost doubled in every case, the SOM of the compost only site crept up slightly.

    My question is: Is there a simple explanation to the doubling of the SOM on the compost tea sites, I can't think of one.

    These guys are very professional and qualified and have been in the industry for many years, I doubt the soil test were done incorrectly. the similarity of the results over many sites was unquestionable

    signed :confused:

    BTW, visually the compost tea sites were close in color, a little less density, basically a close second to the NPK applications but that is to be expected, especially the first year
  2. 44DCNF

    44DCNF LawnSite Bronze Member
    Messages: 1,478

    Clippings and leaves breaking down better under the tea and being reincorporated to the soil rather than blown or dissipated away into the atmosphere as chaff? Worms bringing organic matter into the picture? Very interesting! I always see small twigs pulled into the openings of worm holes in the spring. If they feed on surface debris and return to their tunnels to deficate........more matter in the soil. Anything in the reports on worm numbers or activitiy and how were clippings and leaves handled on these trials? And why limit it to worms, aren't all the microbials doing the same thing in one way or another? As they multiply and pass on they are adding organic matter too, are they not?
  3. growingdeeprootsorganicly

    growingdeeprootsorganicly LawnSite Senior Member
    Messages: 766

  4. NattyLawn

    NattyLawn LawnSite Bronze Member
    Messages: 1,643

    The organic matter jump is a little unbelievable, especially applying tea or ICT only. Did they really apply compost 6 times in one season with little organic matter jump? At what rate was compost applied?

    There are so many variables that could skew results here, so simply doing traditional in the front (probably trying to keep them looking as green as possible for the homeowner) and tea out back isn't really a good test. Do the front and back get the same amount of sun? Traffic? Tree cover/shade? Irrigation? When were the soil samples taken? Before or after application/How soon? How deep were the cores pulled for the sample? 6 apps of compost with cores pulled at 3-5 inches should have given you a decent boost in SOM. Source of compost for the lawn and tea?

    A lot of variables.....
  5. ICT Bill

    ICT Bill LawnSite Platinum Member
    Messages: 4,115

    I agree with the variable statement. I am just wondering if anyone else has had similar results. The extracted tea went from 3.6 to 7.0 and the brewed went from 3.8 to 6.9. The composted site had 2 applications spring and fall.

    One site that had tea had never been fertilized in the 16 years that the person lived there, these were all employees of the company in the trial. The sites are all over a large area, different neighborhoods, different age of subdivisions, etc

    The person who did the physical gathering of the soil at the sites is a very respected well known professional that has been in the industry for over 25 years. The consistancy of the results across all of the tests leaves out operator error

    I can't explain it either, root mass maybe. I would expect some increase but not almost doubling.

    maybe the testing procedure at the lab was not right, if that was the case it is not right on all of them. who knows, I will talk to them again next week and go over the numbers again
  6. Tim Wilson

    Tim Wilson LawnSite Senior Member
    Messages: 795

    I’ll take a whack at a theory. When the SOM testing is done the organic matter which can be comprised primarily of humic substance needs to be isolated from other material like sand, clay and other soil components. This can be done chemically or with heat.

    When compost tea was applied to the areas where the tests were conducted, the higher microbial population, resultant from brewing CT and from the combined microbial inoculants converted older existent non-decayed matter into covalent and noncovalent bonded material. Additionally microbes died and consumed each other creating these humic materials. This humic substance is what shows up in the testing method. We would assume that the identical extraction and testing method was used across all plots, so might conclude that in the case of the compost applied that the degradation and microbial activity is occurring at a more even natural pace and the humic substances may not reach the same levels for an extended time.

    [Because energy=energy the foodstock inputs = large volumes of microbes = humus]

    It would make for an interesting study to follow these plots over a number of years with some manipulation of inputs. (e.g. no application of CT to part of high SOM area & continued applications to part)

    One needs to also consider other variables which may be at play as pointed out by Natty BUT....

    It does seem to support the theory that one can raise certain plants with CT and small amounts of matter or foodstock alone.

    We have done this successfully in a greenhouse for a number of years.

    DUSTYCEDAR LawnSite Fanatic
    from PA
    Messages: 5,134

    just couldent help myself
    are they going to keep testing next year also? in the same areas.
  8. JDUtah

    JDUtah LawnSite Silver Member
    from UT
    Messages: 2,636

    Well thought out Tim.

    I was crudely wondering something similar (If I understood what you said)

    If the lab used an extraction method to test SOM, would this % include the lignin and cellulose molecules found in organic matter? Do the solvents that are used in the extraction technique properly break them down? I assume the heat technique might not have such limitations (if that even is a limitation)?

    If they used extraction, and the above is true- that extraction does not include more complex and stronger bound organic molecules, perhaps the microbes converted these molecules into more 'testable' forms in the respective test plots?

    If that is the case, it would be interesting to see what happens to the SOM over a period of time, like 5 years. Will the SOM diminish to more equilibrated numbers after some time? Stay the same? Continue to increase?

    Interesting stuff. Do they know what SOM test the lab used? Hopefully they plan on testing it for another year or two? Thanks for bringing the info!

    Another factor to consider is if the plot soil was prepared before hand? Was the soil ammended within the last couple years? With what?

    Also fallen leaves? The microbes could have broken them down and significantly incorporated them into the soil before they were removed (worms help)? This could also contribute to an SOM increase (even as a spike?) in the microbe sprayed areas.

    Lol, if this isn't a post full of speculation I don't know what is. But questions are what bring answers huh? Man I am excited to get started with my own stuff (testing/work). Anyone have 25 grand sitting around that they want to invest? lol (before I'm told I can start for less, please understand I have a very specific plan of things)

    'What if' rant over…
  9. growingdeeprootsorganicly

    growingdeeprootsorganicly LawnSite Senior Member
    Messages: 766

    need to know what type of om test used?
  10. Tim Wilson

    Tim Wilson LawnSite Senior Member
    Messages: 795

    As far as I know some chemical extraction techniques can result in cross over contaminants; silica can be dissolved to be included with the organic fractions in the testing as well as some components of non degraded organic material can be dissolved and mixed with the humified matter in terms of the test results.

    My understanding with the heating method is that the material is weighed, then heated to the extent that all carbon components are ‘burnt off’, the material is weighed again. The difference represents the humic (SOM) content. Please correct me if I am wrong on this. It would seem on the surface that the heating method may be less likely to be in error, however there have been recent advances in extraction techniques which are reputed more accurate.

    Because the same method was presumably used on all plots, it is the comparison which is significant.

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