Wine corks for a soil additive - anyone try this?

Has anyone tried putting natural corks (not the synthetic ones) thru a chipper/shredder and using it in your garden to help the texture and prevent compaction? I saw this on a site that recycled natural corks and sold it ground for various things, a garden soil additive being suggested....but I have a source for them and can ensure only natural cork is used....seems like a good organic additive unless I'm missing something.

Corks are bark and ground bark is a good soil additive, so it sounds good in theory.
In the case of my chipper shredder, some things won't go through the blades and it kicks them out unshreded. I think corks would be exactly the kind of thing that would shoot right through.

Batting practice???
Interesting idea with using the cork as a soil amendment.

I would have to qualify "It could be great" by adding "if the size distribution of particles in the soil is conducive to it making a difference and you are using it in a medium that supports adequate water retention and CEC (nutrient retention) before adding the cork.

The cork oak (Quercus suber) got its latin binomial because it's extremely rich in suberin, a natural lipid polymer that restricts water transport across cell walls. Cork is extremely hydrophobic, even repels water from it's surface, so it will reduce water and nutrient retention while retaining its structure for a very long time. The reduction in water retention can be made into a significant plus, or something on a minus depending on how it's used. It couldn't be allelopathic because everything (chemically speaking) is locked so tightly in it's hydrocarbon chains that are practically impervious to breakdown by soil organisms.

I can think of several ways to maximize its usefulness and minimize shortcomings, but if everyone's eyes are already glazed over ...

Al

there was a slight glazing; but I think it has passed with a second reading....please do continue.

The wine makes my eyes more glazed. Lol sorry, I couldn't resist.

Perhaps a meat/sausage grinder instead of a chipper shredder? I have done that with jack-o-lanterns after Halloween so they would compost faster.

If I'm thinking correctly, ground cork would be better suited to improving drainage? Perhaps equivalent to adding perlite?

Tapla....please continue.....I understand that the cork has fats (oils) in it that are nonpolar which repel the water which is polar, like trying to mix water and oil without an emulsifier. I love to hear how it can be used to maximize its short comings.

Let me use an example to illustrate something about the ht of a perched water table, drainage, and aeration first.

Most people think that adding perlite to container media makes a significant increases in o/a aeration and drainage, but does it really? Can ground cork really make a difference in drainage and aeration?

Let's imagine a pint fine sphagnum peat moss - the stuff you by in the compressed bales by the cu ft. When it's wet, there isn't a lot of air space between the particles - not like there would be between a jar full of BBs - right? Let's incrementally start adding perlite or ground cork to the peat & visualize what happens.

Let's start with a handful of perlite - let's call it 4 oz by volume - and mix it well with the peat, so we have a pint of peat and 4 oz of perlite, so the mix is 20% perlite. How much aeration have we added? You can see in the minds eye that every particle of peat or cork is surrounded by peat, which has filled in ALL the space between perlite particles, so there is little if any gain in aeration, and the ht of the soggy layer of soil at the bottom of the pot, the perched water table (PWT), is still about the same as it was in the peat alone.

Let's add 3 more handfuls of perlite (12 more oz), so now have 16 oz of perlite and 16 oz of peat, so the mix is 50/50. See any increase in aeration yet? Is the ht of the PWT much lower? Nope - not yet. You won't see any useful increase in aeration or drainage until the ratio of coarse material to fine material reaches a threshold, at which there is no longer a volume of fine material large enough to fill all the spaces between fine material. This is why you really can't effectively amend water-retentive media by adding pine bark or perlite. The chunky material must be a very high % of the o/a mix so the fine material doesn't clog the air pores. Since the chunky material needs to be such a high % of the mix to make a significant difference, >75%, we're really not amending the fine material, we're adding a small % of fines to the coarse.

Think of a jar full of pudding and ask yourself how much perlite you need to add to make it well-aerated.

Perlite and ground cork serves primarily the function of reducing the amount of water that can be held in a PWT. It essentially takes up space that would otherwise be taken up with peat and water inside and between the peat particles within the PWT. It doesn't really make a significant difference in aeration or drainage (rates) until the ratio of perlite:peat SIGNIFICANTLY favors the % of perlite, such that there is a volume of peat in the soil insufficient to fill the space between particles of perlite or other coarse material. Like ballast (a brick at the bottom of the pot e.g., it serves as ballast within the PWT to reduce how much water (by volume) there is in the PWT.

Chunky cork in pieces of .100-125 (1/10-1/8") mixed into the soil near the bottom of the container would serve the same function as perlite, only better. It could be mixed with any water retentive soil to reduce water retention either within the PWT zone or above that zone. E.g., if you are using a soil that supports 3" of perched water, you could reduce the volume of water in the PWT by approximately 50% by filling the bottom of the container with a 50/50 mix of ground cork and whatever water-retentive mix is being used.

When using the cork, you're going to be sacrificing CEC (the soil's ability to hold nutrients, so you'll need to add something like calcined clay or DE to help with nutrient retention, or resign yourself to the fact you'll need to fertilize more frequently. .

So - best when used to reduce the o/a water retention of soils that tend toward being soggy, and particularly when targeting the amount of water that can be held within the PWT.

Al


This message was edited Nov 3, 2015 6:04 PM

Thanks for the explanation, Al.

Al's pudding analogy makes so much sense, it has stuck with me since the first time I read it.
I think we should all toast our latest soil aeration lesson!