Soil wars - a substrate comparison

[Gustavo Martins]

But but but Monsieur Leatherback already said it is too small a sample so it was but a soiled attempt.

The number of replicates needed is not set in stone. It depends on many things among which the most important is probably the variability of the system. With the results leatherback got, if he measures tree height and applies a simple 1-way ANOVA or t-test, I bet the result will be significant.

 

[Canada Bonsai]

This trial was done with a very small number of plants. From a scientific perspective the number of samples probably is insufficient for statistically sounds conclusions. That being said, with the differences being so clear, I personally feel confident that the pattern seen here is real, and not a coincidence.

As I'm sure you know well, the comparison is especially complex given that a true ceteris paribus is not appropriate in this situation with regards to several variables. Take water for example: watering both substrates 'equally' (i.e. with equal volume and frequency of water) is almost certainly not the best approach when comparing two substrates for your purposes. Rather, the volume and frequency of water would need be adjusted to optimize the performance of each substrate so that you would be comparing each substrate 'at its best'. One could list many variables that would need to be adjusted in this way, but the problem is of course even more complicated than that:

The efficiency of any given substrate is always in proportion with the users ability to use it in an optimal way. That ability varies from person to person and climate to climate, with the potential for maximum optimatizaion (i.e. the 'suitability') of a given substrate also varying from species to species and indeed from tree to tree.

In other words: use what works for you -- there is no need for backyard studies most of all because of the impossibility of performing a controlled and fair experiment. I can pick any substrate and show you the great results that somebody attained using it to achieve a given purpose, and that success has more to do with the user's knowledge, understanding, and adaptability than it does with any substrate being fundamentally 'good' or 'bad'

 

[Cajunrider]

The number of replicates needed is not set in stone. It depends on many things among which the most important is probably the variability of the system. With the results leatherback got, if he measures tree height and applies a simple 1-way ANOVA or t-test, I bet the result will be significant.

Now you are talking dirt..y.

 

[Gustavo Martins]

As I'm sure you know well, the comparison is especially complex given that a true ceteris paribus is not appropriate in this situation with regards to several variables. Take water for example: watering both substrates 'equally' (i.e. with equal volume and frequency of water) is almost certainly not the best approach when comparing two substrates for your purposes. Rather, the volume and frequency of water would need be adjusted to optimize the performance of each substrate so that you would be comparing each substrate 'at its best'. One could list many variables that would need to be adjusted in this way, but the problem is of course even more complicated than that:

The efficiency of any given substrate is always in proportion with the users ability to use it in an optimal way. That ability varies from person to person and climate to climate, with the potential for maximum optimatizaion (i.e. the 'suitability') of a given substrate also varying from species to species and indeed from tree to tree.

In other words: use what works for you -- there is no need for backyard studies most of all because of the impossibility of performing a controlled and fair experiment. I can pick any substrate and show you the great results that somebody attained using it to achieve a given purpose, and that success has more to do with the user's knowledge, understanding, and adaptability than it does with any substrate being fundamentally 'good' or 'bad'

As I'm sure you know well, the comparison is especially complex given that a true ceteris paribus is not appropriate in this situation with regards to several variables. Take water for example: watering both substrates 'equally' (i.e. with equal volume and frequency of water) is almost certainly not the best approach when comparing two substrates for your purposes. Rather, the volume and frequency of water would need be adjusted to optimize the performance of each substrate so that you would be comparing each substrate 'at its best'. One could list many variables that would need to be adjusted in this way, but the problem is of course even more complicated than that:

The efficiency of any given substrate is always in proportion with the users ability to use it in an optimal way. That ability varies from person to person and climate to climate, with the potential for maximum optimatizaion (i.e. the 'suitability') of a given substrate also varying from species to species and indeed from tree to tree.

In other words: use what works for you -- there is no need for backyard studies most of all because of the impossibility of performing a controlled and fair experiment. I can pick any substrate and show you the great results that somebody attained using it to achieve a given purpose, and that success has more to do with the user's knowledge, understanding, and adaptability than it does with any substrate being fundamentally 'good' or 'bad'

I don’t agree. The experiment is small but sound as is. Watering differently each substrate is creating a confounding factor. The result is that, given these conditions where everything is equal except the substrate the result is x and y. Everything is similar/equal except the substrate and the replicates are spatially distributed. If you water different and then have a different result you won’t be able to tease apart the effect of the substrate from that of the watering regime. Different abilities of the substrate to retain water, nutrients etc are all attributes of the substrate. If you are match the two substrates in all the properties then what will you be comparing?

 

[ShadyStump]

I believe he makes a good point here.
In any study we would like to be able to come out with a clear answer, but controlling for every variable is both impractical, and unrealistic to the actual use of the product. At best, any substrate component gets used to half its greatest potential efficiency simply due to weather and human variability. If the different efficiencies found between the control and test substrates are measured in milliliters each day but still produce statistically significant results when taken to that level of detail, then that is NOT useful data for the average person doing bonsai because none of us are taking that level of care to ensure optimum efficiency of a substrate.

Now that's good info to have if you're trying to farm on a space station, or possibly even growing trees on Earth on very large scales where efficiency becomes very important, or maybe even just as something to consider for the sake of debate. But the reality is that we all care allot less about our soil than we do about what's growing in it, so maximizing efficiency of the soil components isn't on our mind so much as maximizing the efficiency of the organism in it. While the two are related, they are not so related that a study THAT detailed would be useful for most of us.

 

[Paradox]

I havent done a scientific experiment with lots of replicates, however I can state the response I got out of one tree when changing substrates only because I bothered to check it months after changing substrates.

I have a scotts pine that Ive had for 10 years. When I first got this pine, I was using a sand and gravel mix. It was HEAVY, too heavy and it retained water because the sand stayed wet even though it drained fairly well.

I decided to repot the tree into a lava and pumice mix. When I pulled it out of the sand mix, I found a root system that had barely grown in the 3 years it had been in that mix.

I repotted it into the lava and pumice and when i checked it a few months later, the amount of root growth was amazing. The tree was much happier in the lava and pumice.

 

[leatherback]

As I'm sure you know well, the comparison is especially complex given that a true ceteris paribus is not appropriate in this situation with regards to several variables. Take water for example: watering both substrates 'equally' (i.e. with equal volume and frequency of water) is almost certainly not the best approach when comparing two substrates for your purposes. Rather, the volume and frequency of water would need be adjusted to optimize the performance of each substrate so that you would be comparing each substrate 'at its best'.

Ah, but here you are scratching on a completely different story. I just wanted to know what Akadama does compared to the regular substrate I was using. I did this already a few years back, when I was figuring out what to use in my pots and still had akadama laying around. Just recently got around writing it up and really thinking about the consequences.

In an ideal world I would have a multivariate analysis, where I have lava / pumice / bark base-mix with either akadama or diatomous earth mixed in, in a randomized blocks. To check the effect of optimized watering, I would have one block where I water every day, one block that gets watered when the akadama gets dry, and one where the DE gets dry. (Highly unpractical as probably the acadama stays wet so long that the plants in DE die). Then compare.

However.. I water ALL my trees in the garden at the same time. Only pines might be spared water when I do my daily dance. That means that I care for them the way I care for all my trees.

Considering the only thing I changed in the setup was the substrate, I am convinced the differences are due to the substrate. WHAT in the substrate causes it, is still open to me. Be it reduce oxygen in the substrate, or some magival tubular structures.. I do not know. I *think* it is the akadama breaking down over time, reducing waterflow & oxygen movement through the soil. And because it is not immediate, but slowly gradually, the roots have time to adjust to the new circumstances, becoming finer. Slow rootgrowth & slow top growth are related, fysiologically, afaik.

there is no need for backyard studies most of all because of the impossibility of performing a controlled and fair experiment.

Maybe not. But for me there is/was a need. I noticed a lot of conflicting opinions and I wanted to see for myself what A does vss B. Now I have seen and this has given me enough reason to re-evaluate my way of doing things. Sorry, my way of doing things include not understanding -> Find a way to understand -> test the idea . Had I had the intent to make this a scientific paper, I would have given it more thought.

 

[leatherback]

The number of replicates needed is not set in stone. It depends on many things among which the most important is probably the variability of the system. With the results leatherback got, if he measures tree height and applies a simple 1-way ANOVA or t-test, I bet the result will be significant.

Probably would have been. But a T-Test with groups of 3 is awfully small still

 

[leatherback]

Maybe air pruning isn't based on air alone, but also tip death from dessication, killing auxin sources, forcing local cytokinin excesses and therefore increasing root ramification.

Ehm.. Not sure what you are pondering here. What you suggest is the mechanism of what is happening, as far as I understand it? It is not the air in itself, it is the roottip dying, triggering new roots forming further back.

 

[Wires_Guy_wires]

Ehm.. Not sure what you are pondering here. What you suggest is the mechanism of what is happening, as far as I understand it? It is not the air in itself, it is the roottip dying, triggering new roots forming further back.

Yeah, exactly. But I think the akadama particle breakdown isn't a part (nor the source) of the root ramification process. People say that a lot, but I am not convinced.
Instead, I think it's everything else.

 

[Kadebe]

Yeah, exactly. But I think the akadama particle breakdown isn't a part (nor the source) of the root ramification process. People say that a lot, but I am not convinced.
Instead, I think it's everything else.

I think that Akadama contributes a lot to root ramification, because the fine roots kan penetrate the Akadama particles. And then of course the particle size matters a lot. I had Lonicera cuttings in small particle soil and the leaves where half of the normal size and also the roots were smaller than in normal soil.