Amy! Where's your experimental spirit? Don't ditch all of the coir, but experiment with it on a conservative basis and report back to us! You've been so enthusiastic about this medium....play with it a little.

That's my advice, anyway. ;-) And that's what I would do.

Rhizo, you're funny. Know what, thats what I was thinking too. As I was gazing at my new containers I decided to fill the third one with Al's mix as he makes it, and leave the first 2 as they are. Maybe I can run more water through them before it gets cold to flush out as much salt as possible, then figure out how to supplement. What about the lime I added? Do you think I raised the ph too much? I guess I could have it tested. I think I will plant the same bulbs now, and annuals in the spring in both mixes and see what gives. Why not?

Thanks, Amy

Amy, it might be possible to save your coir mixture. I have a sneaking suspicion that the coir itself is tying up nutrients and minerals and making them unavailable to your plants' roots. If you add perhaps some clay or, and don't look at me funny when I say this, powdered or ground up charcoal, you may be able to facilitate nutrient exchange and get the plants be happy...without throwing your coir out. Gradually, the coir may decompose and the soil quality would improve for your plants. Concerning the charcoal, the jist of it is that it is very stable (to the point of lasting hundreds or thousands of years) and it serves many beneficial purposes to the plant, including catching and holding nutrients and then releasing them to plant roots when microbes and fungi on the plant roots "dig out" the trapped nutrients. But the chemicals in coir may be toxic to the root microbes (and perhaps the roots themselves), and destroying any such exchange, and quite literally starving the plant. That might be why the addition of extra calcium to the coir mediums used in the paper were fruitless.

Thanks, Maiku
How much charcoal per gallon of medium. Should I flush copiously w/water first for the next month before planting bulbs? I think I can plant as late as Dec., here, even on the 2nd fl. roof.
Amy

I'm assuming that salt, being water-soluble, can be flushed out in a month or so of diligent watering. Should I do that first, then add charcoal and whatever else is reccommended? And, by the way, what else might that be?
Amy

Hi Amy, I recommend 10-30% wood (or lump) charcoal, depending on how easy it is for you to get. I made mine from lump wood charcoal bought at Wal-Mart (10 lb bag for $5, if I remember correctly). Don't use BBQ brisquettes--they can have a lot of clay, coal, and heavy metals in them! But even a small amount of charcoal, according to what I've read in some science papers, is supposed to have a beneficial effect for plants. It'd help to get charcoal with irregular grain shape for drainage and aeration. With my container garden, I've been experimenting with greater and lesser amounts of powder/grainy charcoal in my potting mixture, and the plants do great with 20-40% charcoal. 60-70% isn't recommended. I tried to grow some basil and thyme in that and they didn't want to germinate. Generally, my potting mixtures have been charcoal (20-30%), Miracle-Gro potting mix (20-40%), peat (10%, and I notice it helps seeds germinate very well when sprinkled at the top), and organic fertilizers (bone and blood meal, coffee grounds, tea leaves, and washed, blended seaweed--maybe 10-20%).

You could go ahead and flush with water if you're worried about excessive salt. Normally, nature desalinizes soil by rain, carrying it into the subsoil. Watering for a month, I think, would do the same. You could go ahead and add charcoal before or after watering...I don't think it'll make too much of a difference. And later on, when the bulbs begin to sprout, maybe fertilize to start supplying nutrients. The charcoal should work well with fertilizer. I've also got shallots, garlic, green onions, and leeks growing in the charcoal mixture, and they're thriving, so I hope your bulbs will do the same. One thing I learned recently about charcoal mixed with soil is that its chemical composition and character changes slightly as it gets older and "weathers"--it will gradually become more fertile as some of the carbon in it is converted to weak organic acids through oxidation, which will help with more nutrient, mineral, and water retention and exchange. Even more so out in the garden or farmer's field, where rain & sunshine speed things up.

I've been trying to create something similar to "terra preta"--a black, highly fertile, and microbially rich soil found in South America (especially portions of the Amazon), and it seems the key ingredient is charcoal. Now it doesn't really come as a surprise to me any more after reading some posts here. Orchid potting mix also contains a lot of charcoal, and orchid potting mix isn't just good for orchids. :-)

If interested, these are some sites that got me keen on charcoal for soil:

http://www.deltafarmpress.com/news/051114-terra-preta/
http://www.nature.com/nature/journal/v442/n7103/full/442624a.html (I read and love this magazine more than I can say. Always has delightful articles. One of the two heavy-weight journals of my field.)
http://forums.hypography.com/earth-science/3451-terra-preta.html

My, the post is so long... I hope I haven't put you to sleep.

Thanks, Maiku
Long posts are just more interesting reading.
Do you mean hardwood charcoal used for outdoor cooking? Should I pulverize with a mallet, and then, maybe, a mortar and pestle? How fine? And now, on to read the sites you sent.
Amy

Yes, hardwood charcoal for cooking. If the mallet works for you, you could do it that way. I tried using a hammer initially, but production was slow, hard, and painful. A better method, which I came across by accident, is to shake many pieces in a sturdy, airtight plastic container with a lid, such as a Rubbermaid container. The pieces will pulverize each other and you collect the appropriate size of charcoal you want. I've used grains that were sand-sized to a few millimeters big. It's a bit of work, but a cheap way to get powdered charcoal. In the future, if charcoal production for agriculture and gardening becomes more common, we might be able to buy powdered or pulverized charcoal instead of making it or paying outrageous prices for it (I looked on the internet, and powdered charcoal can sell for like $30 for 2 lbs or so. Oy.).

I wonder where to get it now, out of season. I could put my own hardwood scraps into our wood burning stove but it's not cold enough yet. But, there's no particular rush, at least until I'm ready to plant bulbs. Maybe a kitchen tool, once it's small enough- like an old blender or nut chopper. I have a 50's blender that's as powerful as a new router (woodworking power tool).
Thanks, I'll experiment.
Amy

By the way,
I read through all the sites you suggested. Thanks, really interesting.
Amy

Some time ago I spent a weekend reading about terra preta.

Here are a couple more links - a nice summary:
http://www.css.cornell.edu/faculty/lehmann/publ/BiolFertSoils%2035,%20219-230,%202002%20Glaser.pdf

This would appear to be a 1978 patent on a bark charcoal-type soilless growing medium:
http://www.freepatentsonline.com/4067716.html

"The ability of the combusted bark particles to hold substantially better than 150, even 200, % by weight of water is particularly noteworthy."

The author seems to like this product, with a wetting agent and nutrient additives:
Combusted bark product A 29.5-37%
Canadian peat moss 30-37%
Expanded vermiculite 30%
Sand 3-3.5%

Sorry for the threadjack, Amy

SB

Thanks, SB
I went to the patent page and read the description. Where does one buy such a product? Has it been manufactured? I wasn't able to find that out. I would definately prefer buying it to burning and smashing my own. It certainly sounds like adding charcoal would, at least, do no harm.

Al, Rhizo- are you following this? What do you think?

Amy

Yes - following the thread here. I too had done some study of terra preta over (last) winter with the help of a bryologist (Rick S.) who had contacted me. He sent me a bag of the product that was supposed to be manufactured in similar fashion to the original method. I might be getting my facts a little skewed here, but I believe it had been made to fill a specification for use in water filtration for a city in OH.

I did pot several plants in a kind of experiment with a loose control, but I was so busy this summer I lost track of what I was attempting to evaluate, so cannot report first hand. I can say though, that I use horticultural charcoal in plantings where the plant prefers a wet soil or in plantings where I allow the plant to stand in water to satisfy its thirst.

If you're asking what to do about your coir-containing soil, I can't help. I have also been sent chc's for evaluation, which I'll do in the growth cycle subsequent to spring repot time, but haven't used the coir. I confess to being somewhat skeptical that it will outperform peat in the mixes I use, but I also like to think I am open minded enough to transition to it, should it prove valuable.

I have no opinion on the validity of the U of U study, but I know I will be watching closely for evidence that there might be a problem when using coir.

I probably should read the study again, to see if this is covered, but one thing I might note about any soil that holds high volumes of water is that low oxygen levels cause iron and manganese to become electron acceptors. This leads to their precipitation (iron and manganese) and, even though these elements might be present in soils, the plants inability to assimilate them. Either elemental deficiency will cause the chlorotic effect and certainly, because Fe is instrumental in the maintenance of chlorophyll, it will influence growth. What does all this mean? I suppose I would be very careful about watering practices when using coir.

My observations are completely unfounded, so I would have to defer to any experienced grower if their experience is a + one until I have an opportunity to develop an opinion.

Al

Amy, I think I found a source of pre-mixed charcoal that's easy to get. When I was at Wal-Mart a day ago, I found and bought a bag of Schultz's Orchid Potting Mix, which has quite a lot of charcoal added to it. The pieces are about a half an inch, or slightly bigger or smaller, in size (I got medium, which was all that I saw available). The other ingredients are Western fir bark and ceramic nuggets. In some ways, it sounds similar to Al's potting mix. Aeration and porosity are definitely not issues with this mix. It's a bag of 8 dry quarts and it cost me $7.00. You might be able to find this at a local garden center or home improvement place. I'm thinking of using it to build future potting mixtures, so I don't have to produce so much charcoal (which I've run out of time for with schoolwork & classes). I wish the charcoal pieces were a bit smaller (1/8 to 1/4 in.) for my purposes, but larger might be better for your potting mix since you can fertilize regularly.

Hmm, I wonder why anyone would want to use terra preta for water filtration. Powdered charcoal, definitely. Charcoal has a long history as a filter for many different applications and industries. Terra preta, which is a combination of charcoal bits, ceramic sherds, dirt, humus, microbes, and kitchen waste...why? That water might taste a bit funny... :-)

Stressbaby, the patented potting mix seems pretty good, although it does have higher percentages of peat and vermiculite than I'd use in my own mix. I remember reading somewhere that vermiculite breaks down after a while. Peat breaks down quickly as well. The peat I used to help germinate the seeds in my pots is mostly gone. A few tufts here and there. Great for seed germination and cuttings, I think, but as a long-term additive, maybe not so great?

It was my intent, when I said "He sent me a bag of the product that was supposed to be manufactured in similar fashion to the original method." that it would be taken to mean that I received a bag of charcoal that was manufactured under similar conditions to those under which the charcoal in terra preta was made. It is in a particulate size range of 1/8 to 1/4 ", btw.

Al

Hi Al,

So, maybe the orchid mix "maiku" has found is just the thing. I would rather not have to pulverize it.

I knew you hadn't yet experimented w/coir, and you did advise me to rinse it. I (kind of) did, but maybe not enough before combining it with the other ingredients. I wonder if my mix has too much water retentive stuff, I actually used slightly more coir than the proportion of peat in your mix, even though I like to water. Summer here is brutal, and when I had window boxes I often had to water twice daily. I used more turface than perlite, because it releases water back into the soil. So maybe a combination of factors caused my transplants to grow poorly. It was already labor day, for example. The moonflower vine still grows, but the leaves are tiny. Kale got buggy, arugala didn't grow much. Hyacinth bean yellowed and died after flowering meagerly. It may have been a too-late, too-violent transplant. I did have to tease old roots apart.

All this rambling brings me, finally to my question. I'm now considering "diluting" much of the medium w/the orchid mix. Whaddaya think?
Oh, by the way, do you know where I might find the charcoal material you have?

Amy