Brent

Thank you for the comprehensive reply. At last I got the right answer!
(Theo also said so and I think he was absolutely correct)
Also could you please tell if there are parameters regarding the porosity of
Bonsai mixture? Has anybody conducted research or study on *porosity*. If
you pour water over gravel, the water will drain out in seconds. And if you
do the same on fine grit say with 1 to 2 mm sized particles, it will still
drain out quickly. Likewise it will pass out quickly through fine sand
(dust free) or may take a little longer. How porous the Bonsai potting mix
should be for different climatic conditions? If you have some information
please share.

Regards

Anil Kaushik
Bonsai Club (India)
Chandigarh "The City Beautiful"





Anil Kaushik wrote:


I have not been able to understand why you people do not add natural soil
to
the Bonsai compost! I don't think it can really create problems when
coarse
ingredients like turface, grit and bark are there in the mix. Soil
provides
the basic nutrition to the plants and in fact all flora grow in soil. Or
is
there some other reason for using the soiless compost? In India we use
coarse sand/grit, fertile soil and coarse manure in equal parts and all
the
plants grow well.




Anil

There have been good responses to your question, but I believe there was
only one that was close to my feeling about why you are successful in
your regime while we have chosen our soilless route: The answer, I
believe is the difference in our climates. I am sure that it is as hard
for you to imagine what conditions are like in a temperate climate as it
is for me to comprehend growing in the tropics. None the less, I will
take a crack at it.

The species which you grow and your climate means that there is activity
of some sort year round, although I am sure there are periods of slower
growth. In temperate climates there are long periods of almost no growth
activity whatsoever. What this means is that your soil is in a constant
state of wet/dry cycling. That is, water movement is nearly continual.
Under such conditions, soil decomposition is minimal, and soil collapse
is not not much of a problem. But I do note that you repot every year or
so. At that rate of repotting, particle degradation would not be a
problem even for those of us in a temperate climate. Our repotting rates
are usually two to three years, up to ten years or more for pines. This
longer period argues for more stable constituents.

Additionally, in cold climates, the freeze/thaw cycling in winter is a
factor in particle degradation as is the lack of a proper wet/dry
cycling during the dormant season. Our soils tend to stay WET for most
of the winter, which can be as long as October through March. That is a
very long period of inactivity for a mostly inorganic soil. Use of a
stable soilless mix insures that aeration is still present during this
period, and soil composting is minimal. I seldom notice that my soil
collapses much during the growing season for healthy plants, however at
the end of a winter where we get 30 inches of rain in three or four
months, spring definitely brings signs of soil problems, notably soil
levels sinking in nursery containers.

Now of course, it is possible for us in the temperate zones to grow in a
mix similiar to yours, as it is possible for you to grow in soilless
mixes. I have never been dogmatic about soil mixes, that is why I try to
point out the principles of soil theory rather than a rigid recipe. Each
soil recipe is going to require it's own concomitant regime of watering
and other environmental care. In the tropics, yours works fine with your
cultural practices, in temperate zones we are finding that soilless
mixes work best with our cultural practices. If it works, it works. I
usually don't even question what a person uses for soil if their trees
are healthy. However, when someone isn't satisfied with the growth they
are getting, or have a declining tree, the first thing I do is examine
the soil. Most times the soil is too heavy in organic and fine material,
and so I will recommend a soilless mix. Followup has shown me that I am
usually right about this, as health and vigor improves. But this is for
our climate and our cultural practices. This is a problem in an
international forum, so the realization of such and an appropriate
disclaimer are usually helpful.

Brent
EvergreenGardenworks.com


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