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General Category => General Bonsai Discussion => Topic started by: Markyscott on November 30, 2012, 12:24 AM

Title: Substrate and water retention
Post by: Markyscott on November 30, 2012, 12:24 AM
I thought I'd share the results of a little semi-scientific experiment I carried out. Substrate composition is one of those topics around which there is a tremendous amount of lore, and sorting out meaningful information can be somewhat challenging.  Like many of us, I switched to a inorganic substrate a number of years ago.  But living in a very hot climate and using a soils with low water retention means frequent watering (three times a day in the summer).  I've been very happy with the results, but the hobby has definitely become more of a lifestyle choice than a pass time.  That's not a complaint, but I've become sensitive over the years about water retention.  I had questions, lots of advice, and very few facts:

What inorganic substrate is the most water retentive?
How does grain size influence the amount of water retention?

I purchased several 500 ml beakers and drilled a small hole in the bottom of each:

Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 12:30 AM
I selected the following substrates:

1) Pumice (Wee Tree domestic pumice)
2) Akadama (Double Line)
3) Turface (MVP)
4) Seramis

I sieved each to the following size fractions:

>1/2", 1/2"-3/8", 3/8"-1/4", 1/4"-1/8"

Here's an example of the pumice fractions:

Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 12:35 AM
I filled the beaker with 500 ml of the sieved substrate and poured through 500ml of water (red color is food coloring to help see the water better), measuring the amount that drained out the other end.  The water that fails to drain measures the field capacity (the saturation after the gravitational water has drained away).  Here's an example:



Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 01:14 AM
Here are the results for pumice.  As you can see, the saturation exceeds 23% for the finest grained fraction I tested (1/4-1/8") and decreased wtih increasing grain size to 10% for the coarsest fraction I tested.  When I repeated the test with the same soil, 500ml drained through, a result I interpreted to indicate that the substrate had reached its field capacity on the first watering.

Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 01:29 AM
Here are the results for the 3/8"-1/4" size fraction for the various inorganic substrates.  Seramis was by far the most water retentive at 30% saturation field capacity.  Turface, akadama, and pumice were similar at about 13% saturation field capacity.  I tested decomposed granite as well - as long as it was rinsed thoroughly it had very low water retention (~6%).
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 01:41 AM
Please don't take any of this as an endorsement for any particular brand or soil mix - I wouldn't presume.  But I believe the results suggest a couple of things that were interesting to me:

1) Increasing the fraction of fresh akadama will not appreciably increase the water retention of the soil (unless you're replacing granite).  I understand that akadama breaks down over time and so it's likely that there will be a concommitant increase in water retention as the soil "ages".  These results don't speak to that.

2)  Based on these results alone, if you want a more water retentive mix, one might consider adding Seramis as a component or consider sieving to a finer grain size.  Both of these factors seem to make a pretty big difference in terms of water retention.
Title: Re: Substrate and water retention
Post by: Owen Reich on November 30, 2012, 07:28 AM
Nice project  ;D.  Now you only have to do 5000 more repetitions using different components in various ratios to find "the perfect" one.....  I've never used Seramis.  What is it designed for?

The real kicker is how much each tree takes in in a given season and how to compromise on a mix that works all year where you live.  Where I study, we go for faster draining mixes; there are also apprentices here who check water sometimes 5 times a day and water any given tree 1-3x a day.  It must be nice having "watering drones" as Mike Hagedorn calls them. 

Those tests are a very nice start.  Different containers have different zones of saturation and some pots (especially old Chinese pots and converted suibans) tend to keep more water in the bottom. 

I look forward to hearing more of your results.  It would be great if you combined different components and see how it affects the results. 
Title: Re: Substrate and water retention
Post by: Judy on November 30, 2012, 07:30 AM
Thanks for this experiment,  I've never heard of Seramis?  I'll go google it...

I would also be interested in seeing haydite as one of the components tested, as I've recently started mixing that into my soil mixes.

Do you know how CE rates compare?  This is of as much importance (IMO) as the water retention.
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 07:49 AM
Nice project  ;D.  Now you only have to do 5000 more repetitions using different components in various ratios to find "the perfect" one.....  I've never used Seramis.  What is it designed for?

The real kicker is how much each tree takes in in a given season and how to compromise on a mix that works all year where you live.  Where I study, we go for faster draining mixes; there are also apprentices here who check water sometimes 5 times a day and water any given tree 1-3x a day.  It must be nice having "watering drones" as Mike Hagedorn calls them.  

Those tests are a very nice start.  Different containers have different zones of saturation and some pots (especially old Chinese pots and converted suibans) tend to keep more water in the bottom.  

I look forward to hearing more of your results.  It would be great if you combined different components and see how it affects the results.  

Seramis is a German fired clay product designed for plants - http://www.seramis.com/. (http://www.seramis.com/.)  Its $17 for 7.5L.  There are some videos posted on their site of a similar experiment to what I undertook here.  It's where I got the idea for doing this.  And to do 5000 more tests - yikes - I'd need my own set of watering drones!  I just have 4 kids and a wife who all think I'm a bit off and want no part of my beakers and ziplock baggies filled with gravel.  

In the summer here our climate is pretty tropical - it gets to one thousandty degrees outside (according to my daughter). And the only creatures that seem to like it are the mosquitoes.  During that time, water retention in the soil is a concern for us working folk whose employers frown on their employees taking off every few hours to water our trees.  In the heat of the summer I water before I go to work, have a sprinkler that comes on at mid-day, and water again in the evening - it's usually pretty dry by then.  The good news is that summer only lasts 14 months per year.

Also, its interesting that you mention pots.  I''ve started to look at water retention as a funtion of the pot shape.  I haven't finished that yet, but directionally it appears that an equivalent volume of soil has a higher field capacity in a shallow pot than it does in a deeper pot.  It also appears that adding a drainage layer has the same effect (it makes the mix more water retentive).  I'll post more on that later.  Not sure why old Chinese pots in particular would make a particular difference - if you send me a few, I'd be happy to test them for you!

I have tested some mixes as well - I'll post those results later.

Scott
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 08:06 AM
Thanks for this experiment,  I've never heard of Seramis?  I'll go google it...

I would also be interested in seeing haydite as one of the components tested, as I've recently started mixing that into my soil mixes.

Do you know how CE rates compare?  This is of as much importance (IMO) as the water retention.

Not sure what you mean by CE rates.  Are you referring to cation exchange capacity (CEC)?

Also - haydite is on my list.  I'm a little low on it now and couldn't get enough after sieving to test all the size fractions.  I have to wait to make another trip to the nursery to restock.  Directionally, it looked as though it has a bit lower field capacity than the other fired clays (seramis, akadama, and turface).

Scott
Title: Re: Substrate and water retention
Post by: Judy on November 30, 2012, 09:47 AM
Yes I was meaning CEC. 
I did a test between haydite and turface this summer, it wasn't as practical as yours however.  I measured equal cup size amounts, added equal amounts of water to each (done in buckets not in a pour thru situation), then I compared the dry weight of each sample with the wet weight after I drained them for an equal amount of time.  The turface was a bit more water retentive, but only slightly by my test.  I was looking for comparison results with your method.  Please post them if you do another test. 
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 10:37 AM
Yes I was meaning CEC.  
I did a test between haydite and turface this summer, it wasn't as practical as yours however.  I measured equal cup size amounts, added equal amounts of water to each (done in buckets not in a pour thru situation), then I compared the dry weight of each sample with the wet weight after I drained them for an equal amount of time.  The turface was a bit more water retentive, but only slightly by my test.  I was looking for comparison results with your method.  Please post them if you do another test.  

I've not had CEC measured myself, but I've references from publications that I can pass along.  My memory is that, although there is some variability, CEC is pretty low (relative to organics) for the components that I reported on here.  

When one increases drainage one must water a lot.  When one goes with all inorganics one must fertilize a lot.  Of the two, watering is my biggest issue because it must be done multiple times a day in the summer and if I miss a day or two, plants die.  Fertilizing is less critical for me because I can work it in around my schedule and if I miss it once or twice I don't have to attend to any funerals.

Cheers
Scott
Title: Re: Substrate and water retention
Post by: Chrisl on November 30, 2012, 10:47 AM
<it gets to one thousandty degrees outside (according to my daughter). And the only creatures that seem to like it are the mosquitoes....The good news is that summer only lasts 14 months per year.>

Having lived in Houston for over ten years, I can attest to this...very funny Scott!

And Thanks for posting your results, quite interesting results at that.  Nice to know Turface and Akadama are about the same. 
Title: Re: Substrate and water retention
Post by: Yenling83 on November 30, 2012, 10:52 AM
Thanks for the post! very interesting.  I'd imagine Double Red Line Akadama would hold more and more water as it breaks down-but that's just a guess.  I would have also guessed that fresh Akadama would have still held more water than turface.  I'd be interested to see where lava compares with the rest. 

So can you not set your sprinklers to water another time during the day when your at work?   
Title: Re: Substrate and water retention
Post by: sekibonsai on November 30, 2012, 11:17 AM
Are you sourcing seramis locally or do you order it online?
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 11:44 AM
Are you sourcing seramis locally or do you order it online?

Ordered it online from the website above.  Shipping costs are reasonable as it's pretty low density (similar to pumice).

Scott
Title: Re: Substrate and water retention
Post by: 0soyoung on November 30, 2012, 01:54 PM
Thank you Markyscott. Well done, IMHO.

It seems to me that the depth of saturation zone ought to be independent of pot shape. This could be simply and easily demonstrated to be true/false by using another column with a significantly different diameter than the one you've been using. One would observe the depth of water retained in each column - is it or is it not the same.

Again, kudos, for demonstrating a little basic scientific analysis. Most refreshing!

I hope to see more.

Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 02:11 PM
Thanks for the post! very interesting.  I'd imagine Double Red Line Akadama would hold more and more water as it breaks down-but that's just a guess.  I would have also guessed that fresh Akadama would have still held more water than turface.  I'd be interested to see where lava compares with the rest. 

So can you not set your sprinklers to water another time during the day when your at work?   

I think it does break down a bit over time in the pot.  Fine-grained akadama behaves like fine-grained pumice - it becomes more water retentive.  So my intuition is aligned with yours - it should probably become more retentive over time.  Here that might be a good thing as a more mature root system has higher water demands.

In this test, Turface was consistently a bit more water retentive than akadama. The issue I had when preparing the material was the grain size - Turface mvp is pretty fine grained compared to the other material, so to get 500ml of 3/8-1/4" turface, I had to do a lot of sieving and there were a lot of fines that ended up getting discarded.  I hate doing all that manual labor only to have 1/2 of it end up in the compost heap.  Oh well - my aspidistra looks great!

Re the sprinklers - the answer is yes there is some optimization to do there.  Good thing I like projects.

Scott
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 02:53 PM
Thank you Markyscott. Well done, IMHO.

It seems to me that the depth of saturation zone ought to be independent of pot shape. This could be simply and easily demonstrated to be true/false by using another column with a significantly different diameter than the one you've been using. One would observe the depth of water retained in each column - is it or is it not the same.

Again, kudos, for demonstrating a little basic scientific analysis. Most refreshing!

I hope to see more.


Thanks 0soyoung - I appreciate your feedback.  The soil saturation profile is pretty well understood and I think you're right in that the profile is independent of the shape of the container.  What it is related to is depth (saturation increases with depth) and porosity (saturation increases with decreasing porosity).  Porosity is proportional to grain size.  So as you move up from the soil at the base of the pot, the saturation is initially very high and then drops off as you move toward the soil surface.  You might be able to see the bright band at the bottom of the beaker in one of my previous posts.  Within that zone the saturation was close to 100%.  The zone was taller with finer grain sizes.  I don't expect that to change with the diameter of the beaker as it's related to the capillary properties of the soil.

But here's how the field capacity (the amount of water in the soil after all the gravitational water has drained away) is related to the shape of the pot.  As I pointed out above, the saturation at the bottom of the pot is high and drops off with distance from the bottom. If you only have a little way to go (in a shallow pot, say) the saturation doesn't drop off much before you reach the soil surface.  If you're looking at a deeper pot you can go up further and the saturation can drop off considerably more.  So in the beaker (think of it as a very tall pot) only a small fraction of the 500 ml of soil has that very high saturation.  If I spread that 500ml of soil out into a thin layer, the entire volume of soil would have have a very high saturation, so field capacity is much higher.  Visualize a sponge standing on end vs a sponge lying flat.  The flat-lying sponge will hold more water then the sponge standing on end because of this same effect.

Here's an interesting aside.  What does the drainage layer do?  Essentially, it makes the pot shallower, moving the higher saturation zone normally at the bottom of the pot shallower as it will sit on top of the "drainage layer" - it makes a perched water table, so to speak.  So there is no increase in drainage with a drainage layer (the 500ml of soil has the same field capacity whether it is sitting on a drainage layer or not.  What it does is move the wet zone off the bottom of the pot.

Scott
Title: Re: Substrate and water retention
Post by: 0soyoung on November 30, 2012, 03:48 PM
Right on - I agree whole heartedly and as you've laid it out for all to see, it is easy to demonstrate these facts.

So when one has an anchient and prized tree, in a hot climate like the environs of Edo and Kyoto in the summer time, one puts coarse soil at the bottom of the pot so the roots along the bottom of the root pad aren't sitting in saturated soil. Then Owen, for example, puts finer soil around the upper edges of the pad so that there is ample water for roots near the surface that also have to contend with evaporation loss. I do believe this is why the misnamed/misunderstood "drainage layer" appears in his videos. It is not for drainage, per se, and calling such just obfuscates what it is about.

Again, thanks for the expose and discussion. I love science and glad you do too!

What's next?
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 04:12 PM
Right on - I agree whole heartedly and as you've laid it out for all to see, it is easy to demonstrate these facts.

So when one has an anchient and prized tree, in a hot climate like the environs of Edo and Kyoto in the summer time, one puts coarse soil at the bottom of the pot so the roots along the bottom of the root pad aren't sitting in saturated soil. Then Owen, for example, puts finer soil around the upper edges of the pad so that there is ample water for roots near the surface that also have to contend with evaporation loss. I do believe this is why the misnamed/misunderstood "drainage layer" appears in his videos. It is not for drainage, per se, and calling such just obfuscates what it is about.

Again, thanks for the expose and discussion. I love science and glad you do too!

What's next?

Thanks again 0soyoung.  For me it's helpful to develop a physical intuition about what's going on so that when recommendations such as these are made based largely on experience, I have some capacity for reasoning the physical basis for them.  

A question struck me as I was reading your inference about the effect of the drainage layer.  Does it keep the roots at the bottom of the pot out of the highly saturated zone, or does it encourage more feeder root development above the drainage layer and away from the pot edge where it is cooler and the feeder roots are less susceptible to damage from contact with the heated pot?  You've given me something to think about.

In the short term I'll post some results of the tests on other substrates and soil compositions.  Then I want to think about "soil pH" - another factor I hear a lot of conflicting information about.

Scott
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 06:52 PM
Here's an interesting plot.  It compares the water retention capacity of four baked clay products: Seramis, Turface, Akadama, and Haydite as a function of grain diameter.

Title: Re: Substrate and water retention
Post by: John Kirby on November 30, 2012, 06:59 PM
Haydite isn't baked clay, it is expanded shale (think popped popcorn). I guess the surface adherance of water is having a greater pact than substrate, in general terms. Now replicate 5,000 times, Owen is waiting with bated breath.
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 07:11 PM
Haydite isn't baked clay, it is expanded shale (think popped popcorn). I guess the surface adherance of water is having a greater pact than substrate, in general terms. Now replicate 5,000 times, Owen is waiting with bated breath.

Thanks for the correction, John.  And I have all my bonsai minions feverishly working on the 5000 replications.

Scott
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 07:25 PM
Same plot as before, but with my version of "Boon mix" added.  Houston, not being in an important volcanic province, is poorly supplied with scoria.  So scoria is replaced with haydite in my version to save cost a bit: equal parts akadama, pumice, and haydite along with a bit of granite and charcoal.  Note that the water retention is a little better than any of the components alone.  Not as high as turface or seramis, but higher than akadama, haydite, or pumice.  Here are a couple of possibile explanations:

1) Grain shape is an important control on equilibrium saturation.  It's possible that the mix of grain shapes lowers the porosity somewhat and, as a result, increases the capillary held water.

2) I was pretty thorough about removing the dust from the substrate I was using for the experiments as I rinsed it all and then dried thoroughly.  I seived the mix to remove the dust when mixing the soil.  I seived again before the experiment, but did not rinse and dry as it takes several days.  This may have skewed the results somewhat to higher water retention for the mixture.

Other ideas?
Title: Re: Substrate and water retention
Post by: 0soyoung on November 30, 2012, 07:47 PM
Suppose that each element of the mix was as its own layer 'cake' of a soil. Isn't it obvious that the total retention would be the weighted average of the individual components, where the weight is the relative proportion of the total. At a glance I would say that is what you've got - the weighted average. This would simply say that the extra stuff like charcoal was negligable in this case and that there's nothing 'exotic' going on. Simiarly if it is homogenous (i.e., well mixed) the saturation depth would be the weighted average, wouldn't it?

On the other hand, if something exotic was happening, the total volume of your soil would be less than the sum of the component volumes. Alcohol in water is like this. Alcohol molecules fit in spaces between water molecules so that 1 volume of water and an equal of alcohol makes less than 2 volumes mixed.
Title: Re: Substrate and water retention
Post by: John Kirby on November 30, 2012, 07:54 PM
Remember, two points make a straight line, so the straight lines may or may not have any relevance. But, what couldn be interesting would be to see the variance at each of the common mean particle sizes- from 3-4 measures per point. My students often get irritated when I ask them if two measurements are actually different. Based on what you have shown, I am not sure that you can actually say that any of the means are actually different using inference. But I certainly like your approach.

One more thing, with measures such as depth and temperature and vapor pressure and flux, I would bet a Pepsi Cola that you are not looking at a simple linear equation.

But I am just a grumpy old cuss.
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 08:18 PM
Remember, two points make a straight line, so the straight lines may or may not have any relevance. But, what couldn be interesting would be to see the variance at each of the common mean particle sizes- from 3-4 measures per point. My students often get irritated when I ask them if two measurements are actually different. Based on what you have shown, I am not sure that you can actually say that any of the means are actually different using inference. But I certainly like your approach.

One more thing, with measures such as depth and temperature and vapor pressure and flux, I would bet a Pepsi Cola that you are not looking at a simple linear equation.

But I am just a grumpy old cuss.

All good points GOC - in my defense I pointed out that it was semi-scientific at the beginning.  Not ready for a Nature paper yet, to be sure but when it is, I'm looking for a good co-author.  Here are some thoughts:

Point 1 - I actually expected the curves to behave more linearly with porosity than grain size, but they don't for some reason. 

Point 2 - You're right that the experiment needs to be repeated for the different points to establish the variability.  I'll continue to run these and I'll post updates occassionally when I have additional data.  But it can take several days to thoroughly dry the soil between experiments, so there are some practical limits to how fast I can turn around the data.

Point 3 - Probably not a linear equation as equilibrium saturation is strongly related to angularity, sorting, and porosity as well as average grain size.  But for this system and the data I've collected so far, it appears to behave fairly linearly with respect to grain size over the range of sizes that I tested.

Cheers
Scott
Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 08:31 PM
One more observation before bed time.  When testing Turface I had an abundance of fines, so I tested a cut with about a 1/8" average grain size.  The results were pretty interesting - when I poured the water through, there was a significant amount of channelization.  Once a saturated path was connected through the beaker, most of the water flowed through the channel leaving portions of the substrate unwetted.  Pouring more water through did not significantly wet the dry spots.  Even after pouring several times the soil volume of water through the beaker dry spots remained.  I've attached a photo (sorry for the picture quality) taken after having poured 2000ml of water through the 500 ml of soil.  The light areas are dry spots that remained.  I poured 4000ml of water through the 500ml of soil and the dry spots remained.  Increasing the average grain size seemed to eliminate this problem.

Having dry spots in the substrate after watering is probably something to be avoided.  I can imagine that this might kill feeder roots and weaken the tree in the long run.  If you leave fines in the substrate, be aware that this can happen and take care with the watering.  It might take much more than you think to thoroughly wet the medium.

Cheers
Scott
Title: Re: Substrate and water retention
Post by: John Kirby on November 30, 2012, 08:45 PM
Well, you can rationalize just about anything, especially if you can make a reasonable graphical representation!

As I inferred, I salute your efforts. However, I wouldn't draw many conclusions other than stuff in pots hold water. It is kind if like recording the temperature on a monday, tues,wed,thurs, fri, sat and a sunday. Then, making the statement "On Monday the temperature was 70 F, on Tuesday the temperature was  72,etc.,and then concluding "Tuesdays are warmer than Mondays."

Great little book out there that helps with these kinds of things, called "How to lie with Statistics", great examples of how graphs and figures can unintentionally lead to unusual interpretations.

Thanks Scott for stimulating a fun conversation!



Title: Re: Substrate and water retention
Post by: Markyscott on November 30, 2012, 08:49 PM
Well, you can rationalize just about anything, especially if you can make a reasonable graphical representation!

As I inferred, I salute your efforts. However, I wouldn't draw many conclusions other than stuff in pots hold water. It is kind if like recording the temperature on a monday, tues,wed,thurs, fri, sat and a sunday. Then, making the statement "On Monday the temperature was 70 F, on Tuesday the temperature was  72,etc.,and then concluding "Tuesdays are warmer than Mondays."

Great little book out there that helps with these kinds of things, called "How to lie with Statistics", great examples of how graphs and figures can unintentionally lead to unusual interpretations.

Thanks Scott for stimulating a fun conversation!





Just here to help.  And thanks for joining in, John - I appreciate healthy skepticism.  But I have to ask - were you surprised by the inverse relationship between grain size and saturation?  I agree that the simple tests I've done here prove nothing by themselves, but the relationship conforms to capillary theory and the values are not out of range of saturated porous media that I've worked with in the past.

- Scott
Title: Re: Substrate and water retention
Post by: John Kirby on December 01, 2012, 08:00 AM
Oh, just to be complete, the opposite is true as well. Based on the data shown, the differences that you claim can not be disproven either, without more data. Thus, it is kind that you have agreed to have your Droids replicate the experiment. I am not sure that 5000 replicates would be required, but an idea of the variability would add great insight.
Title: Re: Substrate and water retention
Post by: Chrisl on December 01, 2012, 12:32 PM
Agreed, a very interesting topic Scott!  And those dry channels in the fines is really surprising.  I've used fines in sev. air layers and it works great.  Maybe only b/c it was only 4" deep? 
Title: Re: Substrate and water retention
Post by: 0soyoung on December 01, 2012, 01:04 PM
Oh, just to be complete, the opposite is true as well. Based on the data shown, the differences that you claim can not be disproven either, without more data. Thus, it is kind that you have agreed to have your Droids replicate the experiment. I am not sure that 5000 replicates would be required, but an idea of the variability would add great insight.

It takes at least 5 replicates to be reasonably confident of the mean and over 30 for the dispersion about the mean (which would represent measurement errors, variation in the particles sizes in each category, and whatever else contributes to variability in the tests).
Title: Re: Substrate and water retention
Post by: John Kirby on December 01, 2012, 03:04 PM
Actually, 5 would give you more information but it may or may not give any more confidence in the results. Since we do not know what the variability is for each point of measurement, we can not estimate the sample size necessary to separate the means among and between soil types or sizes. The variability due to the method appliedmay very well hide any differences due to soil size or composition. Sokol and Rohlf has a well defined formula to determine sample sizes required to detect differences, however you will need more data to estimate.
Title: Re: Substrate and water retention
Post by: Tex Guy on December 01, 2012, 03:54 PM
I have to confess that this has not been my "go to" bonsai source.  But that may change as a result of this discussion.  A while ago I had an urban yamadori opporutinity and dug about a dozen old boxwoods from someone's house.  Needing something to put them in and not wanting to spend a fortune I did some quick research and settled on expanded shale mixed with organic material.  But finding how cheap expanded shale is I decided to do an experiement of my own.  So my methodology was completely different than Mary's.  And the products tested, while overlapping, were quite different.

I first dried all the materials for 12 hours in a convection oven at 200 degrees.  Then I weighed each product. Then I Submerged 500ml of each product in water for 24 hours.  Finally, I drained the products and re-weighed.  So let's recognize that my attempt at a test didn't appreciate particle size.  Nor did it measure in any way water retentiveness over time, only initial retentiveness.  But for what it's worth, here is a table with my results...

                      APL          Akadama          Expanded Shale   Dyna Rok           Pumice
wt, dry             322             306                  378                     166             290
               
wt, 24 hr soak     436             436                  462                     386             398
               
Retain H2O ML     114             130                   84                     220             108

In this case APL is 1/3 Akadama double red line, 1/3 Pumice, 1/3 Lava

The take away for me is the performance of Dyna Rok as a retentive medium. 

I love to see CEC info on any and all of the media discussed in this thread.
Title: Re: Substrate and water retention
Post by: crust on December 01, 2012, 04:55 PM
Dyna rock is a tempting product but at 60 bucks a bag... are there any users out there?
Title: Re: Substrate and water retention
Post by: 0soyoung on December 01, 2012, 05:06 PM


I love to see CEC info on any and all of the media discussed in this thread.


see frankP999's post http://bonsaistudygroup.com/general-discussion/akadama-substitutes/msg15899/#msg15899 (http://bonsaistudygroup.com/general-discussion/akadama-substitutes/msg15899/#msg15899), for example.
Title: Re: Substrate and water retention
Post by: John Kirby on December 01, 2012, 05:28 PM
I have looked at Dyna rock, but have not used, also waste glass products, but still have not used.

For those of you who might have trouble sleeping tonight, or want to design an experiment to resolve this water and soil issue, a nice overview piece is to be found at: http://www.statsoft.com/textbook/power-analysis/ (http://www.statsoft.com/textbook/power-analysis/)
Title: Re: Substrate and water retention
Post by: Don Dunn on January 24, 2013, 11:08 PM
Judy
 Where do  you  get your haydite ? I was going to try it also and so I went to the local rockery where they also have a large concrete mixing plant and fill and deliver their own concrete. I walked in and asked if they had any haydite and they asked what is haydite. I explained it to them and there was no one in the whole place that had ever heard of it. A crowd had gathered  by then and I was starting to fell a bit embarased thinking maybe I had confused my information. They were all very interested and promptly they looked it up on their computer. I finally felt vindicated when they found it and said they were going to do more research their self. Well, so now where can I get some, if the concrete people don't even know what it is?
Title: Re: Substrate and water retention
Post by: Jerry Norbury on January 25, 2013, 02:29 AM
Can someone also do Napa diatomaceous earth/European cat litter?
Title: Re: Substrate and water retention
Post by: Judy on January 25, 2013, 07:03 AM
We have a company here in Ohio that produces expanded shale products called DiGeronimo Aggregates.

http://www.digeronimoaggregates.com/ (http://www.digeronimoaggregates.com/)

I can drive up there and get it in bulk, for reasonable prices.  There is a guy up there that sells a soil mix which has haydite, river rock, bark, and charcoal.  I know he sells on ebay, and thru internet site, and his prices seem reasonable.  I know he would just sell you straight haydite if you wanted it.  The company name is The Bonsai Den.

http://www.thebonsaiden.com/Soils.html (http://www.thebonsaiden.com/Soils.html)

Let me know if you want any additional information, hope this helps. 
Title: Re: Substrate and water retention
Post by: Anthony on January 26, 2013, 07:11 PM
Just in case anyone wants to know, been using our local crushed, sifted, porous, fired red earthenware brick since 1983 or so [ Seramis ?] as an ingredient in my bonsai soils. The other two ingredients are sifted silca based builder's gravel and compost.

If you added the brick to peat moss, at say 1/3, the peat moss is not really able to dry out, as the brick re-wets easily and immediately, also moisturizing the peat moss, and brick doesn't float.

Presently we are going through our drying out winds stage of the Dry Season, and I have to water once in the evening before 5.30 p.m and twice in the morning. Exposure is full sun, 6 to 6. Soil mix handles the gale force winds well - chuckle.

It is amusing to see from the Seramis website, all this excitement. Still the plant on the youtube example was not bare rooted.
Hmm in the 1980's the Germans also marketed an expanded rounded clay as well for houseplant hydroponics.
Back to transplanting and the temperature is still around 68 deg.F at night, the trees are still sleeping/dormant.
From the tropics, good evening.
Anthony
Title: Re: Substrate and water retention
Post by: Don Dunn on January 26, 2013, 07:47 PM
Where in the world do you live Anthony

68 deg.F at night,  my guess is Australia.
 I'm in sunny California and we are going to be 37 deg. F. tonight.
Title: Re: Substrate and water retention
Post by: Anthony on January 26, 2013, 09:18 PM
No Don,

I am in the West Indies [ Caribbean ], and that should give you an idea of the range of temperatures found in the Tropics.For if I lived in Jamaica or Venzuela, I could see frost as well, and possibly snow -chuckle.
Good Evening.
Anthony.
Title: Re: Substrate and water retention
Post by: Anthony on January 28, 2013, 04:23 AM
Interesting, today the sun rose and all of my pots started sweating, especially the dark plastic ones. No actual sunlight hitting the pots mind you, weird, similar to what one observes on the outside of a glass filled with ice cold water.

Think it is time to stick a thermometer into the soil and see what is going on.
Good Morning.
Anthony