A Soil Story

bisco_bonsai

A soil story:
I sat through a lecture the other day on soils by a very distinguished hort professor who was talking about the benefits/drawbacks of the different soil ingredients for greenhouse applications. He briefly mentioned Turface which peaked my interest, but disregarded it right off the bat because its weight would cause a huge expense in shipping for large greenhouse operations. Well, after the class, I asked him a question (not mentioning anything about bonsai) which I thought would be helpful in a bonsai application. I asked, "Dr. _____, taking cost, availability, and all other factors out of the media buying process, which would be the absolute, best soil mix for greenhouses (this was the frame of my question) to use?" His surprising answer: "There would be no need for a mix, we would all be using Turface solely by itself."
Taken back, I asked why; he responded, "Turface is the perfect media for any controlled growing environment, the calcined clay is sterile after the baking treatment, it holds water, nutrients, promotes aeration, all in all it is the perfect soil ingredient, but you would never be able to hire any employees once they found out that they would have to be carrying around pots filled with Tturface. One of the main reasons we have the mixes we use today is the weight consideration, which significantly impacts both physical labor and shipping cost."
So here is a guy that has probably never touched a bonsai in his life, but has more letters after his name than I can imagine possible telling me that turface alone is the best media for a controlled growing environment. Hmmmm, I think to myself, maybe all those guys preaching the benefits of a totally inorganic soil mix aren't crazy after all. Could it be that creating these complicated mixes with hours of sifting and sieving aren't the best choice? I guess it's worth thinking about.
All the best,
JDL

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BrianBay9

Interesting JDL. I've only been in bonsai for six years, but I now use 70 - 100% turface for my trees, depending on the species (the rest is composted rice hulls). I do not sift anything...the turface drains well without sifting, even after three of four years in the pot. I have no controlled experiments, but my trees in 100% turface are doing great. I think your horticulture prof is brilliant....brilliant defined as agreeing with me...lol.

Cheers
Brian

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Will_Heath

Sterile is a key word here. What about the beneficial Bactria and fungus that are important to plants?

Straight turface will drain at the same rate and retain the same amount of water, air, and nutrients no matter what species of tree is planted in it. How then, besides having 18 different watering schedules would you adjust for dry loving trees such as pines or wet loving trees such as Wisteria?

We must also remember the standard size of turface, hardly big enough for normal sized bonsai but good for Shohin sizes. Although I have aquired some turface that consits of 1/8 inch particles, it is hard to find and expensive.


Will

Carl_Bergstrom

Hi Will, I don't agree with you entirely here. A couple of remarks:



When you use organic fertilizer on a sterile inorganic medium (e.g. pure akadama) these develop quickly (perhaps by windborne spores - I don't know.)



Though I adjust component sizes according to pot size, I use exactly the same mix across species - with good results. I water everything to saturation, daily. With a good well-draining inorganic mix, this is not a problem for the dry-loving species (say, bristlecone) nor for the wet-loving (say, wisteria.) Presumably this is easier to get away with in Seattle than in Dallas, but anyway....

Cheers,
Carl

Will_Heath

Hi Carl,

Thanks for taking the time to bring these points up.


Of course, good point, these can be introduced, even by adding a small amount of the old soil to the new mix.


I would think that Seattle would be wetter than my climate.

I use a very free draining mix and theoretically could water every hour on the hour without over wetting my soil. However, I still find that my pines (Muhgos, Spruce, and Larch excluded.) enjoy it more when I wait until they are almost completely dry before watering again. Sometimes this is twice a day in July, sometimes it is every third day. It all depends on the temperature, the wind, the cloud cover, and the growth rate of the tree.

Having a mix that does not allow you to over-water is great but it does not cover the other end of the equation which is the species that prefer to dry out between waterings, on these I do not water daily.

I have found that the amount of time it takes for a mix to dry out varies even on the same species depending on such small things as location, time of day watered, and if my neighbor watered his lawn on that day.

My mind has a hard time imagining giving my Wisteria and my pines the same amount of water on a daily basis. Although, I must admit that your results are hard to debate.

Respectfully,


Will

bisco_bonsai

I don't see why starting with sterile soil would be good for most nusery plants and bad for bonsai. With exposure to the environment, I'm sure the sterile soil will not stay sterile for long, but it's a good place to start, providing that appropriate fertilization is given to the plant. Lastly, I'm not sure which would be better, adjusting your soil to the specific tree, or adjusting your watering to the specific tree. To me, I think intuitively I wouldn't give a pine as much water as say a maple. Adjusting the soil for all my trees so that I can water them as a group seems like a good idea at first, but I think a nice consistent soil mix across species that will perform just as well for each might have its merits. Of course, adding a little more grit or bark here and there to accomodate a specific species wouldn't be so bad after all.
All the best,
JDL

Joanie

Ahhhh the deepest questions of Life. So many possible answers, and no perfect one.

Are you reading this thread? Lots of good information here, including the organic/inorganic suggestions for different trees, and why they are important.

As Will points out, you could grow trees in glass shards if you paid enough attention to them and gave them adequate water and ferts. Perhaps for the greenhouse, with controlled conditions and generally similar plants, one perfect soil could cover it. After all, in greenhouse growing they want the lushest plants so they give them lots of fertilizer. The plants are climate controlled and watered on a schedule. We, on the other hand, and bringing in trees from the deserts or from the swamps. We can't control the climate or humidity, and we don't always want the lushest growth. We want controlled growth.

Joanie

Will_Heath

Joanie, excellent points!



Will

rockm

"don't see why starting with sterile soil would be good for most nusery plants and bad for bonsai. With exposure to the environment, I'm sure the sterile soil will not stay sterile for long, but it's a good place to start, providing that appropriate fertilization is given to the plant."

It's not a question of "bad for bonsai." It more about healthy nursery plants. Sterile soil helps keep down the diseases that can devastate nursery plants quickly. The point the guy was making was that it's good that turface STARTS OUT sterile and isn't a reservoir of disease, as some potting soil can be. A soil bourne pathogen can kill off big investments at large nurseries.