Soil Stratification-applications to bonsai

16-Mar-2005

#11

Alasdair

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Quote:

Originally Posted by Todd_Renshaw

(Which is best probably depends upon your watering habits and local environment too.)

just re-read my post and was about to edit to include this lol.

Al

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16-Mar-2005	#12
bisco_bonsai NCSU Horticulture Join Date: Jan-2005 Location: NC Country: USA USDA Zone: 7b AHS Heat Zone: 7 Posts: 194	Thanks for all the response folks. First of all, in response to cato42's question, a perched water table is when an abrupt change in soil texture causes standing water to fill the macropores in your soil. In response to Will, I agree that the bottom of the pot forms this same change in texture to prevent water from flowing, but you have to remember that the bottom of the pot has enormous drainage holes (in relation to soil particles) to let the water drain out of the macropores. After all, optimum plant available water does not come about from this type of "standing" water filling the macropores. It is actually quite the opposite. The optimum level of plant available water is when there is no water (gravitational) filling the macropores, but only the water which is bound (adhesion) to the surface of the individual soil particles. On the large scale, it is called "field capacity." Of course this means that the gravitational water that would normally be perching is going to drain out faster and present a situation where watering would have to be more frequent. Actually, if you could get your soil stratified perfectly from large particles at the bottom to gradually smaller at the top, you could, in a sense, make water flow uphill through capillary action. Yes, that's right, water can flow uphill; it is done in the field all the time if the situation warrants it. Anyway, I still think that the science teaches that the best way to produce the maximum plant available water is through soil texture uniformity. After all, the use of more granular soil in bonsai suggests that the goal is no standing water in the macropores, as well as no colloidal effects of course. I do admit that I don't know how precisely this translates into bonsai culture, and I'm certainly not going to argue with experience. Once again, thanks for all the responses. I think this is a very fascinating subject. All the best, JDL Last edited by bisco_bonsai : 16-Mar-2005 at 04:27 PM.

16-Mar-2005	#13
Joanie Enthusiast *MODERATOR GROUP* Join Date: Feb-2005 Location: Carlsbad, California..coastal desert Country: United States USDA Zone: 11 AHS Heat Zone: 2 Posts: 5,412	Why not test it? Why not test it? If you "potted" both types of soil into clear containers, simulating a bonsai pot, you could actually see what goes on, couldn't you? Maybe a couple of liter bottles, cut down and with drainage holes? Watch it over several weeks, water it as if it has a tree in it. Just a thought.... Joanie (who just barely got a good soil mix going, let alone stratifying!!)

16-Mar-2005	#14
bisco_bonsai NCSU Horticulture Join Date: Jan-2005 Location: NC Country: USA USDA Zone: 7b AHS Heat Zone: 7 Posts: 194	Joanie, these kind of tests have been done and uniformity seems to be the scientific answer for providing the best plant-available water, but seeing as how we are measuring what is best for the plant, I think that the plant should be part of the experiment as well. However, there are so many variable to plant growth and health that I don't think you could pin down a superior soil stucture with any certainty. Even if you determine that one soil type is best at holding water (stratified) through this kind of bulk density experiment, I don't think you can determine if the extra water is plant available (non-gravitational). I'm sure that this can be measured, but it is beyond my knowledge. For now, I will settle with my perched water table with drainage holes (bottom of the pot) over a perched water table in the form of an extra layer. If the goal is to get rid of the excess water (gravitational), I don't see how you can argue that stratification is better than uniformity. But that's just my two cents. All the best, JDL

17-Mar-2005	#15
bisco_bonsai NCSU Horticulture Join Date: Jan-2005 Location: NC Country: USA USDA Zone: 7b AHS Heat Zone: 7 Posts: 194	What about using a larger size particle of the same texture at the bottom of the pot instead of gravel? By this I mean using larger clay particle under smaller clay particles instead of using gravel under smaller clay particles. This might actually increase capillarity and wick water back up to the roots instead of creating perched water in the macropores. Any reason why this wouldn't work? You could just save all your larger particles after sieving you soil, mix them together, and create a sort of "bottom dressing" that is the same soil texture as the soil above. Just a thought. All the best, JDL

18-Mar-2005

#16

Will_Heath

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Quote:

Originally Posted by bisco_bonsai

What about using a larger size particle of the same texture at the bottom of the pot instead of gravel?

This is the way it is usually done... You use the larger particles of your mix after screening for the bottom layer.

Will Heath

18-Mar-2005	#17
Newt bonsaiTALK Master Craftsman Join Date: Sep-2004 Location: Augusta Country: USA USDA Zone: 5 AHS Heat Zone: ? Posts: 565	If you really want the best drainage put a "wick" coming out the drain hole. I watched a demo by Dean Bull. I am not sure if there is anything on the web regarding his techniques. He uses straight turface with a "rayon wick" coming out the drain holes. You buy a Rayon mop head then cut the strings of rayon off. you can try this with an existing bonsai if you want to see it in action. Water your tree well and let it drain till no more water comes out. Next take your tweezers and stick the wick up through your drainage hole (go to the side of your drainage screen). You will need a bench with slats or a milk crate so the wick will hang straight down (the longer the wick the more wicking action). Next put a bucket under the wick and come back in a hour or so. You will be amazed at the amount of water that comes out! Newt __________________ Opportunity must not be lost while the gods smile. -Li Jing

18-Mar-2005	#18
bonsaikc Registered FedEx Sender Join Date: Jan-2004 Location: Ottawa, KS Country: USA USDA Zone: 5-6 AHS Heat Zone: 7 Posts: 1,614	According to Dave DeGroot, curator of the Pacific Rim collection, perched water tables occur in nature only in the presence of a constant influx of water, so it's not only the makeup of the soil that causes this condition. If you are keeping the hose running in your pot, perhaps you could perch your water. We use a layer of pumice at the bottom of the pot (haydite if you can't get pumice), but not very deep. The soil is not graded as to size, the pumice being the same size as the soil particles. And the only time I top-dress is when potting a high altitude conifer and using a large soil mix (3/8 to 1/2 inch). This controversy pops up perennially and gets no end of heat, and never much light. Chris __________________ Chris Johnston "She was a critic, and lots fo critics who aren't called to do what they write about grow jealous and mean and small in their disappointment." - Stephen King, Duma Key Sashi-no-eda.blogspot.com

18-Mar-2005	#19
Treebeard Tree herder Join Date: Aug-2002 Location: Maidenhead Country: England USDA Zone: 8b AHS Heat Zone: ? Posts: 2,200	This link http://edis.ifas.ufl.edu/BODY_CN004 has a lot of info on what you chaps are discussing, and a whole lot of other info besides. It is not specifically bonsai-related, but useful nonetheless. Regards, Chris. __________________ "Do not be hasty, that is my motto" -JRR Tolkien, The Two Towers. ----------------------------------- christopherguise.co.uk

18-Mar-2005	#20
John Dixon Air Assault All The Way. Join Date: Mar-2004 Location: Huntersville, NC (near Charlotte) Country: USA USDA Zone: 7-8 AHS Heat Zone: 7 Posts: 1,695	I use both methods and have always viewed the bottom layer as a barrier to waterlogging. It accomplishes two things in my book: 1) any irregularities in the pot's bottom that could "pool" water are lower than the rootball and the coarse rock adds to aeration and evaporation of stagnant water. 2) the coarse rock will not easily support the growth of new roots (although some will be there) and keeps them from waterlogging and rotting (which will eventually lead up to the rest of the rootball). Drainage and aeration are critical needs to bonsai. Since we should be watering frequently, a heavily moisture laden layer of bottom soil serves no useful purpose. With aeration available at both the bottom and top of the soil surface, we can expect a more consistent soil moisture and adapt our watering techniques, as needed. I feel this will work for any species, but I tend to use it for less-thirsty species like pines and junipers more than any other. I also find I use it more on large trees rather than small ones. On the small and medium size trees, say to 24", I just tend to use straight mix. Coarser for trees I want to have produce more growth and finer particles for trees that are established and/or on the smaller side. If you have no idea what particle size does in regards to moisture here is a quick way to explain it in your kitchen. If you have an ice dispenser that puts out both cubed and crushed ice. Fill two identical size glasses with both kinds of ice. Just fill them equally to the top. Now fill both with COLD water to the top. Immediately (hey this is ice we're talking about), strain the water out of both glasses into two equally sized containers. Without fail you will have more "water" in the glass with the larger cubes. Simple physics. There are more areas of open space, because there are less sides of particles to form together. Now the other side of this is that although there is more initial room for moisture, in a bonsai pot coarser soil will provide quicker drainage and less moisture-retention if the material is not capable of absorption. These are much more important factors to consider in soil selection. I hope we can all find a happy medium (pun intended). John __________________ John Dixon Si vis pacem parabellum Stay off the trails of others, that's where the booby-traps are.

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