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pine bark fines for amending soil

Posted by joeschmoe 6 (Ohio) (My Page) on
Wed, Dec 26, 12 at 9:39

I've heard many good and a few bad things about "pine bark fines" for amending (tilling/digging into) soil.

First - I've heard you should only use composted or partially composted fines, as fresh can steal nitrogen and kill beneficial fungi in the soil. The only place near me, Ohio Mulch, who sells Pine Bark "fines" seems to suggest it's not composted, but I haven't called to confirm yet.

Secondly - how much acidity does it really add? While I'm not trying "per se" to acidify, a "little" acidity won't hurt, since my limestone-based soil is about a half-point more alkaline than what is ideal anyway.

Third - who has used it? Have you used it solo, or with other amendments?

Follow-Up Postings:

RE: pine bark fines for amending soil

Any wood based, or rather celullous based soil amendment can make N unavailable as it decomposes. This is true for all wood chips and even leaves. If you use uncomposted pine, you may also want to consider a source of N, whether that be a fertilizer or a manure. You may also consider buying now and composting for a year.

If you have limestone based soil, pine will have relatively little to no effect on your soil ph. It takes a lot of acid amendments to reduce PH in limestone derived soils, though it can be done if your water source does not come from a limestone drainage. If your water sources comes from a limestone drainage, it is nearly impossible to change your soil PH at all. The good news is that most garden plants grow well in wide range of soil PH's.

RE: pine bark fines for amending soil

My pH when I did a home test came back about 6.9, but the professional test results said 7.2. Other than blueberries and a few others, most plants do "OK", but I'd feel better if I could get it into the mid 6's. That said, organic matter is the higher goal.

I heard that pine BARK is better than WOOD for N-robbing issues.

What if I mixed in a little blood meal to offset the nitrogen issues? How much would be the right amount?

The professional soil test came back from the lab with "low, adequate, high, surplus" and the N was just at "adequate".

I should post my results, actually, but I need to scan it since they sent it on paper and not a .pdf.

RE: pine bark fines for amending soil

IMO it depends on what one is really buying when the label says "pine bark fines" as I've heard it can vary.

This year I've been fortunate to get shredded coniferous bark mulch in large quantity so have mulched all my perennial beds generously. I know the bark will get mixed with the soil as I transplant so I plan to use alfalfa pellets to offset the negative nitrogen balance. How much will be needed I have no idea but I'll be generous. Alfalfa pellets are a good relatively inexpensive amendment which I've used a lot in the past and I don't think it's detrimental to overuse. I'll only use them around specific plants, not over the entire garden.

My bark mulch had started decomposing and was quite warm in places so I think it will be beneficial to my soil.

I don't know how much bark fines will acidify the soil but I wouldn't mind a little as my soil is alkaline. I think with constant composting it will balance so I'm not concerned about pH. Of course where I live there is not an acid rain problem. Might be different in other areas.

This post was edited by luckygal on Wed, Dec 26, 12 at 18:50

RE: pine bark fines for amending soil

Pine bark in Scots Pine, for example, has more lignin (45%) than cellulose (25%) and tends to not tie up N like wood chips might (although it may a little bit). It seems to favor fungal growth over bacterial growth. Wood chips, of course would be another matter. Again using Scots Pine, the lignin (28%) to cellulose (40%) ratio is almost reversed and would be an issue with N and perhaps fungal growth for a time.

It may slightly lower your pH but should not be a factor if you are at 7.2. Its all about dosage. ;-)

With N being so volatile and readings dependent on so many factors it is just a gee-whiz number and most universities don't test for it.

Bottom line, I'd use pine bark and keep an eye out for signs of N being tied up. Also check to see how much is really bark and how much is wood as this can vary.


RE: pine bark fines for amending soil

I've used it to top dress less attractive mulches. Though I haven't confirmed this lately, it's often sold as "soil conditioner" around here (the land of red clay). Good stuff, though using it exclusively as a mulch I've noticed it tends to shed rainwater.

RE: pine bark fines for amending soil

Bark mulches have a Carbon to Nitrogen ratio of around 500 to 1 so using them as a soil amendment (tilled in) will cause a temporary Nitrogen deficiency in the soil as the Soil Food Web digests this material. If that bark is composted then it will be compost, not just composted bark. If it is just rotted bark, bark piled up and allowed to sit for a while, it is not compost and has not been composted.
Studies by Dr. Abigail Maynard at the New Haven, Conn Ag Research Station found that adding lots of Oak leaves or Pine needles to soils for several years did not have any significant affect on the soils pH, so it is highly unlikely that pine bark fines would have much of any affect either.
I found that mixing in 3.8 cubic feet of peat moss into a planting bed that was 4 feet by 4 feet to a depth of 8 inches changed that soils pH from 5.7 to 7.2.

RE: pine bark fines for amending soil

Thanks for the info.

Kimmsr, weird that the peat INCREASED pH. Perhaps it's because as it decomposed and became humus, it neutralized as most organic material does, even if it starts out acid?

As far as amending my soil, what about a one-two punch, so to speak?

I start off by using some pine bark fines (preferably partially composted, but fresh could probably work) to incorporate into soil to loosen and break it up short-term. Maybe throw in some alfalfa meal or blood meal to offset any potential N deficiency.

As it decomposes, slowly, eventually it will turn into organic matter that will do the same thing as the bulk of the fines themselves initially will do, i.e., improve aeration and drainage, at the same time I add more organic matter on top as mulch, probably shredded leaves from the wooded lot next door (most of them blow into my yard) and/or compost of various sources.

Now, to Allen--maybe using pure pine bark as mulch on TOP would be bad, since it can be hydrophobic (a good quality, however, incorporated into clay that tends to get mucky wet). What about mixing pine bark with compost or shredded leaves for aesthetics? Would it likely then be OK for water penetration?

RE: pine bark fines for amending soil

I have not found that bark mulches shed that much rain water, although some does splash off. The soil under the pine bark nuggets, large, medium, small, has always been moist provided I put down more than 2 inches of it. I have noticed that the large pine bark nuggets last longer then do the small ones.

RE: pine bark fines for amending soil

I do most of my gardening in large containers due to soil issues caused by black walnut trees. Two years ago I used pine fines sold by Ohio Mulch to make the 5-1-1 mix in my containers, and then last summer I recycled more than 10 cubic feet of the used mix into a few small garden plots along with some yard waste compost. The vegetables and flowers I grew in those plots did very well with only a small amount of organic fertilizer added in. I didn't do any soil testing because I didn't see any problems. The pine fines from Ohio mulch are not composted, but the pieces are mostly well under 1/2 inch wide and began to compost slowly in my pots. I really like that product.

RE: pine bark fines for amending soil

Yea, it is best to use composted wood chips. To improve a given area some composted mulch and 'biocompost' which is local compost made from yard and kitchen waste is best.

I have used pine to ammend soil and it drained well at first but the addition of just a little compost and the use of fertilizer you dont need much.

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