Leaf Compost

Discussion in 'Organic Lawn Care' started by Pistol, Mar 11, 2009.

  1. phasthound

    phasthound LawnSite Platinum Member
    Messages: 4,926

    I'm able to pick up leaf compost at one town for $9.00/yard. My home town delivers it for free to residents. :)

    I suppose I should have bioassays done on them.
  2. cudaclan

    cudaclan LawnSite Member
    from Zone 5
    Messages: 152

    Is there a risk of seeds germinating? Maple seeds overunned my pile and required hand weeding. I would still use the material as mulch.
  3. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,315

    Must be insider knowledge ... didn't know he was using it for CT as well. :)

  4. quackgrass

    quackgrass LawnSite Senior Member
    Messages: 253

    One thing you should consider is the pH of the leaf compost. It commonly has the highest pH and sometimes it can be too high. (unless you suffer from low pH)

    Its better used as an organic soil amendment - to retain moisture, than a nutritional source, since it has very little. Its closer to a peat than a bio-solid.

    If you have higher pH soils, (7+) I wouldn't recommend it for most lawns or plants needing lower pH. It will actually harm them.

    Some leaf composts will raise the soil pH one point or more.
  5. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,315

    This doesn't quite sit right with me. Granted some composts can be above neutral, but to raise the soil pH a full unit .... I'm not following that. Do you have some references?
  6. quackgrass

    quackgrass LawnSite Senior Member
    Messages: 253


    Note that it mentions this happened with a particular source of leaf compost - not all.

    I have gathered hundreds, if not thousands of samples of various composts in the North West. My experience has been that leaf compost tends to have the highest pH unless it contains a lot of conifer needles.
  7. LTL

    LTL LawnSite Member
    from Tulsa
    Messages: 98

    I checked with a company here that sells leaf compost and the pH of their compost is 7.5. A little high for me.
  8. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,315

    Thanks for the link. :)

    Note that is also happened in a very specific type of soil too, and that the effect was transitory.
    Also note how in all cases except 1 (Comtil Compost) the pH tended towards neutral over time.

    Couple of things that jumped out at me on the quick read through.

    -- SOM of >20% in year 3! Not a condition you are likely to see very often in your typical mineral soil. IMO, most people are not going to add 4" of compost in a 2 year period to any site (TG withstanding).

    -- The compost was rototilled in to a 6" depth. Once again, this is not something most people do. A Compost topdress is the typical method of application, at best coupled with an aeration for turf. If a complete site overhaul is in order, then a rototill may take place.

    -- No pH values were given for the compost and the initial soil test results were somewhat lacking in information nor were they given for each test period.

    -- The sources of the leaf compost were not disclosed, or at least I did not see them.

    -- One last thing, no indication of whether or not irrigation took place which could affect soil pH.

    No offense intended, but you need to be very careful with blanket statements (or nearly so) as the potential for misunderstanding is way too high. IMHO, most people would have walked away from your post with the conclusion that leaf compost = bad in all soils with pH neutral or higher and in all conditions of use. We both know this is hardly true.

    Some info I pulled out of my archive in the event you are interested. Shows leaf composts can range from pH 4.3-8.

    http://www.aqua-enviro.net/pdf/Leaf Composting Final Report.pdf
  9. quackgrass

    quackgrass LawnSite Senior Member
    Messages: 253

    Blanket statement? - ouch. I thought I had brought up an import consideration. The link was posted because you were skeptical of leaf compost raising pH. My opinion on the matter is based on what I have seen - not read from a link. so disputing one study won't change my mind.

    I would hope that people walked away aware of a possibility that leaf compost can have a high pH, and it may not be suitable as a topdressing material in high pH soils. Other products would certainly be more effective.

    If anything my comments helped people make a more informed decision. It offered a means to raise pH or avoid it.

    I certainly wouldn't want someone putting a high pH material on my soil if the pH needed to go down!

    Are you saying that Leaf compost is always a suitable topdressing material?
  10. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,315

    You absolutely did ... but the way it was presented could lead to confusion. It is a dynamic of this forum more than anything. At times people read what they want to see, not what is written. The first impression I got from your post was, leaf compost is bad, and if I were looking to make a decision to use or not, that is the answer I would have walked away with. Just so you know, I'm not looking for an argument here, I just wanted you to clarify the information you had presented.

    I am still skeptical because what is true for you may not be true for me, or for anyone else outside your region. What are the reasons for the change in soil pH and is it even due to the leaf compost?
    Is this something that is specific to your regions leaf sources and soil, or is it something that can be extended to all sources and soils?

    Leaf composts vary in pH and a soils ability to buffer pH changes will dictate how much of an impact any amendment will have on the overall pH of the system. Generally speaking, OM will tend to move pH towards neutrality over time in a mineral soil as well as increase the soils ability to buffer changes in pH. This is probably the most important relationship between SOM and pH people need to walk away with here.

    I applaud informed decisions. :clapping:

    I think the question we need to ask is if a leaf compost is your only source, will 1/8" - 1/4" topdressing once or twice a year lead to a long term detrimental pH change? I don't believe it will, and the benefits from OM addition in this case (leaf compost) will far outweigh the potential chance of a short term undesirable pH change.

    Irrigation water can also lead to an undesirable pH change (and other undesirable conditions), but that doesn't mean you won't use it to water your plants.

    If that is your only source of bulk organic matter .... I would probably say yes, it is, with adjustments if needed. Amend it with sulfur or some other appropriate source of acidity if the pH is too high. Given the most likely low N, you will probably want to amend it before applying anyhow.

    We are not talking composts high in salts, heavy metals, and other toxics here, but a relatively "safe" compost in comparison to some of the other choices. In most cases it will be leaves from local sources, which IMO use of which is not much different than just letting the leaves stay where they fall, or mulching them back into the turf when cutting.

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