Ph issue if composting pine needles and chipped up pine branches

toffee-el(Z8b Sunset Z13 Elev 4650ft)February 25, 2013

Need to clear bunch of ponderosa pine trees for build site. I am thinking of saving the tree trunks as firewood and to start some Hugelkultur raised beds. I also plan to chip up the smaller branches and needles for new compost bins.

Since pine is the only material other than asking for horse manure from neighbor. Would the finished compost be very acidic? The soil is very sandy at this location and covered by pine needles already.

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bluegoat_gw(Zone 3b)

Coniferous needles are no more acidic than other leaves.


A pH between 5.5 and 8.5 is optimal for compost microorganisms. As bacteria and fungi digest organic matter, they release organic acids. In the early stages of composting, these acids often accumulate. The resulting drop in pH encourages the growth of fungi and the breakdown of lignin and cellulose. Usually the organic acids become further broken down during the composting process. If the system becomes anaerobic, however, acid accumulation can lower the pH to 4.5, severely limiting microbial activity. In such cases, aeration usually is sufficient to return the compost pH to acceptable ranges.

Here is a link that might be useful: Compost Chemistry

    Bookmark   February 25, 2013 at 5:27PM
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AND the composting process tends to bring all the materials toward neutral pH anyway. So compost away, and happy rotting!

    Bookmark   February 25, 2013 at 6:38PM
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Pine needles, when bruised and soaked in distilled water for at least 24 hours will test at about 3.5 pH but when composted the finished compost will be near 7.0 or neutral. That soil may be acidic, not because of the pines or needles but because the soil Calcium or Magnesium has been washed out by the rains that may have fallen. Sand, without adequate levels of organic matter, tends not to hold any nutrients very well.

    Bookmark   February 26, 2013 at 6:46AM
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toffee-el(Z8b Sunset Z13 Elev 4650ft)

Since I am cutting quite a few trees to create a build site, I will have a large pile of chipped up pine branches, needles, weeds. Will try to get as much as horse manure (probably fresh) from neighbors to mix in with the pile too. But as we are heading into the dry seasons here in California, this pile will not get to stay wet. Being dry, how long would it take to become usable compost?

This pile will be the foundation of my new compost for the next few years.

    Bookmark   February 26, 2013 at 11:39AM
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If you have large equipment coming in, you should take advantage of it, already dig the vegetable beds and bury the trunks there. In the future, the water retention of those beds will be much better. I don't think a log belongs in the compost pile. You might consider injecting the logs with edible mushrooms for a secondary, totally free harvest. Phoenix Oyster is indicated for conifers.

The branches and needles, shredded and mixed with manure, can form the proper pile, though things will work just as well if you place all of it on top of the beds. Assuming you make a pile, it will help if you place it in shade, but the occasional hosing will keep it going through the summer.

    Bookmark   February 26, 2013 at 1:50PM
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toffee-el(Z8b Sunset Z13 Elev 4650ft)

You are right gbib. My plan is to save the logs for hugelkultur, and leverage the heavy equipment to dig the trenches where the logs will sit.

I am leaning towards raised hugel beds, so digging would be 1-1.5ft but longish, say 16ft. Probably go for 4 of them. Got to figure out orientation though, east-west or north-south.

    Bookmark   February 26, 2013 at 5:52PM
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If the tree shreddings are fresh, and the manure is fresh and urine-soaked it won't take long to get finished compost out of a pile.

    Bookmark   March 1, 2013 at 9:58AM
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Can I accelerate pine needle (acid) composting by mixing with wood ash (base) and keeping the mixture moist?

    Bookmark   May 4, 2013 at 12:59PM
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If you use pine needles...compost to finish. This is very important if you're worried about pH.

You can compost almost anything on the pH scale and eventually get it at/near neutral, but you have to finish the process.

Thanks to high lignin, wax, and cellulose content, this can take a while in some environments.

Pine bark is rather pH neutral on it's own...broken down or not.

    Bookmark   May 4, 2013 at 4:52PM
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Conrad, there is no good reason to mix wood ash with pine needles when you are composting them, or even when adding them to your soil because those pine needles will not significantly change your soils pH . The wood ash will change your soils pH, for a short time, if that soil needs a pH change.

Here is a link that might be useful: pine needle pH

    Bookmark   May 4, 2013 at 5:33PM
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