Gardening science versus tradition

Discussion in 'Plants: Science and Cultivation' started by Margot, Jul 26, 2020.

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  1. Margot

    Margot Generous Contributor

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    I know it may seem presumptuous of me to repost this comment I made on the Is this Autumn Blaze Maple worth saving? thread. My reply is a bit off-topic in that context but, I think, deserves wider consideration and comments from forum contributors-at-large.

    The issue, as I see it, is whether new scientific revelations about good gardening practices should replace tried-and-true methods, anecdotal as they are. Obviously, I'm not neutral on this: I think they should.
    __________________________________________________________________________
    I have read all 40-or-so of Dr. Linda Chalker-Scott's "Horticultural Myths" Linda Chalker-Scott | Washington State University at least once and many of them, several times. I have changed my gardening practices drastically over the years because of the science-based evidence she presents that shows there is often a better way of gardening than what was recommended in the past. Often too, we formerly did things and used products that have been proven to be uneccessary, wasting time and money.

    For my own interest, I quickly made this list of a few changes I have made over the past few years:
    · don't use bone meal or epsom salts (The Myth of Beneficial Bone Meal)
    · don’t paint cut ends of branches or wounds (The Myth of Wound Dressings)
    · avoid manures and other mulches or amendments containing phosphate (Several articles)
    · do not put drainage material in containers (The Myth of Drainage Material in Container Plantings)
    · never use landscape fabric, newspaper or cardboard to suppress weeds (The Myth of Landscape Fabric)
    · do not amend the surrounding soil when planting trees or shrubs (The Myth of Soil Amendments – Parts I, II & III)
    · avoid staking newly-planted trees if at all possible (The Myth of Staking)
    · loosen roots of perennials, shrubs and trees before planting (The Myth of Fragile Roots)
    · leave leaves and other ‘clean’ plant debris under shrubs and trees

    It has been difficult sometimes to put my faith in new practices when I have seemingly been successful doing things the way my parents did decades ago. However, when I read the scientific evidence showing how plants grow and respond to their environments, I cannot ignore the logic.

     
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  2. Acerholic

    Acerholic Esteemed Contributor Forums Moderator VCBF Cherry Scout Maple Society

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    @Margot, a very interesting thread that I respect totally. I am a traditionalist as you have probably realised.
    As a father of three children who have science MSC' s in various sciences and teach these subjects, I am aware of the need to challenge everything, even scientific papers.
    I am of the opinion if it is not broken don't try to fix it. Maybe an old fashioned principle but it works for me.
    This is why whenever I reply, or a person asks for advice, I say this is what I do or IMO.
    I would never presume to suggest that my way is the best or the only way to garden.
    Debating a subject is a very healthy way to obtain more information.
    For that reason I think this is an excellent thread by you and put across in a tactful and pleasant way.
     
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  3. Sulev

    Sulev Active Member

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    This mythbuster is too shallow and narrowminded, therefore I recommend to use your own brain when judging whether to follow traditional methods or her mythbusting recommendations.
     
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  4. Margot

    Margot Generous Contributor

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    I hope you do not feel similarly about all scientific research as you seem about research Dr. Chalker-Scott has compiled from studies undertaken by a wide number of respected scientists. To label her a shallow, narrow-minded myth-buster is unwarranted and unnecessary.

    Of course, all of us gardeners are free to do what we wish in our gardens; for me it is important to make informed decisions.
     
  5. Sulev

    Sulev Active Member

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    Scientists are usually objective and do define the range of conditions where their theory is valid. I don't see that in case of the mythbuster Linda.
     
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  6. Ron B

    Ron B Paragon of Plants 10 Years

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    Carl E. Whitcomb and associates were using organized experiments to investigate supposedly tried and true cultural practices, finding them to have no scientific basis decades ago. For instance he was the

    First to determine that, contrary to the ‘accepted fact’ at the time, soil amendments in the planting hole are not only of no benefit but also often restrict rate of plant establishment (1969-1974,with graduate students Robert Burns in Gainesville, Florida and pure sand soils and Joe Schulte in Oklahoma in productive sandy clay loam field soil and subsoil clay).

    Schulte, Joseph R. and Carl E. Whitcomb. 1975. Effects of Soil Amendments and Fertilizer Levels on the Establishment of Silver Maple. Journal of Arboriculture, volume 1, pages 192-195


    Home Page
     
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  7. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    @Margot,
    This seems like good topic in which to conduct a poll. May I suggest you add one to your original post?
     
  8. Margot

    Margot Generous Contributor

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    Thank you for the suggestion, @Junglekeeper but I don't think objective validity can be determined by the popularity of an idea. For example, if there were a poll on the value of vaccines, many people would say that they are ineffective and dangerous which has nothing to do with the science that proves that they are, overall, worthwhile.
     
  9. Sulev

    Sulev Active Member

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    Do you really think, that vaccines are absolutely safe and all these possible adverse side effects, described in vaccine's information paper, are myths?
     
  10. Sulev

    Sulev Active Member

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    I live on top of deep sands, originating from former glacial lake. Below my orchard there is at least 40 metres of clear white sand, that is excavated in the neighborhood and sold for construction. Of course, it is possible to grow plants in various soils and even without it by providing all the nutrients by water solution, but I am sure, that I was not able to grow my fruits without amending the soil. In fact, all the top soil in my orchard is amended. But planting hole for trees still usually reaches down to the white sand.
    Does this research and myth busting consider such options?
     

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    Last edited: Jul 28, 2020
  11. Sulev

    Sulev Active Member

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    To me, a myth-buster is an entertainer, not a scientist. Her conclusions are not objective, but aimed for getting bigger entertainment effect - being more intriguing, reaching wider auditorium, getting more fame, better selling, etc.

    For instance, a myth-buster concludes, that amending planting holes is a bad idea, as this renders soil either too wet or too dry, and roots would not spread to the surrounding soil.

    A scientist would say: use these and these amendments in a planting hole for creating more moist (better water retention) conditions for plant roots in these (list of dryish soil types) soil types and conditions, if needed. And use these and these amendments for creating more dry conditions for plant roots in these (list of wettish soil types) soils types and conditions, if needed. And concludes, that it is not reasonable (and could be harmful or simply not economical) to amend soil in a planting hole where there is no need for improving nutrient balance, pH or moisture regime of the original soil.

    One can amend the soil only minimally, or replace even entirely. That's huge range of adjustability. A scientist could say, from where there is a limit, from where certain amendment may turn harmful at certain conditions.

    Even fact, that plant roots tend to stay inside the amended soil and not spread so well to the surrounding soil, if the amended soil has much better conditions than surrounding soil, can be useful. I personally don't like if my plums, cherries, pears, apple trees and currants spread their roots into neighboring beds. I take into account, that because my trees and bushes are planted into amended soil, their root system is more compact and can be more sensitive in case of long drought. I have to water these trees during longer dry spells anyways, it's no big problem to do that more often with smaller amount of water at a time. Of course, I don't use such a small planting holes as described in the scientific test, mentioned by Ron B (Schulte, Joseph R. and Carl E. Whitcomb. 1975. Effects of Soil Amendments and Fertilizer Levels on the Establishment of Silver Maple. Journal of Arboriculture, volume 1, pages 192-195 ), where holes were only 12 inches deep and 24 inches in diameter. Even for shrubs my planting holes are at least 50 cm deep, and holes for trees are usually more than 1 metre.

    I think, that traditional recommendations to amend the soil in a planting hole is caused by a fact, that traditionally houses were built on the driest/rockiest and lowest fertile soils of the property and more fertile soils were reserved for fields. Orchards and decorative gardens around the homes came later and therefore met problem with low soil fertility and dryness when planting trees and shrubs. Nowadays that is often not true any more as building developments are pushing onto former fields around cities disregarding soil fertility.
    I think, that a scientist would know that and would not attack traditions with a blind hate.

    I could analogically criticize almost any other myth-busting by Linda (I have no experience with some of her myths, for instance that, concerning use of bone meal, as here it has never been popular to use a bone meal as a fertilizer), but I think I already made my point.
     
  12. Margot

    Margot Generous Contributor

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    @Sulev - why don't you contact Dr. Chalker-Scott yourself and explain to her how a scientist ought to think.

    lindacs@wsu.edu
     
  13. Sulev

    Sulev Active Member

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    Because I don't care. I think, that world needs entertainers also, not only scientists. I just do not understand, why to promote myth busting here, this is already at least third thread here where you try to promote her myth-busting? I suppose, that this is serious forum about gardening and plants. I will not start to backfill my planting holes with a clean white sand around the roots anyways.
     
  14. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    I'd like to see Dr. Chalker-Scott respond to the aspersions. Perhaps she should be invited to provide a rebuttal.
     
    Last edited: Jul 30, 2020
  15. Sulev

    Sulev Active Member

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    I'd like to see a characterization, hypothesis, prediction, methodology, results/numerical observations and maybe even analysis together with conclusions, not conclusions only, when discussing science vs myths. Otherwise it's just creation of new myths, because it remains unknown in what conditions the conclusion is valid (if it is valid at all).
     
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  16. Sulev

    Sulev Active Member

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    Even with seemingly serious scientific study it is possible to get wrong conclusions if the experiment is poorly designed or executed.
    A sample of a poor experiment design is on the attached image.
     

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  17. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    Well, I did contact Dr. Chalker-Scott, who replied that it is her practice not to get involved in the many social media posts and discussions that take issue with things she has written. She went on to say:

    I do suggest, however, that you (or others who are interested) join our FB group, which is linked below and has over 24K members. It’s devoted to science-based gardening discussions, and then it’s not just an LCS issue. Also, our blog and our peer-reviewed Extension fact sheets are linked below. I don’t know which site is being used/abused, but if it’s just the first in my list below, that’s pretty much an archive. Newer information is in the aforementioned links.

    Hope this is helpful –

    Linda

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    Linda Chalker-Scott, PhD
    Associate Professor and Extension Urban Horticulturist
    WSU PREC
    2606 W Pioneer
    Puyallup, WA 98371

    "The Informed Gardener" webpage: www.theinformedgardener.com
    "The Garden Professors" blog: www.gardenprofessors.com
    "The Garden Professors" Facebook page: www.facebook.com/TheGardenProfessors
    "The Garden Professors" Facebook group: www.facebook.com/groups/GardenProfessors
    “Gardening in Washington State” fact sheets: Gardening in Washington State | Washington State University
     
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  18. Nik

    Nik Rising Contributor

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    This is a thread that is too heated, and needs a moderator attention.
    All I will say is that if you participate in FB , you are partially responsible for the decay of present day democracy.
     
  19. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    I don't think any bounds have been overstepped yet. People can be allowed to disagree and say why. Really, from the get-go, Margot dared people to disagree with her position, and Sulev has gone to some effort to back up his points. Maybe there is incivility intended behind some of the comments, but I think as they stand so far, they're fine. It's not really a discussion if everybody says the same thing.
     
  20. Sulev

    Sulev Active Member

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    I don't use Facebook, but other links seem not contain any original research by Dr. Chalker-Scott, only conclusions based on (possibly cherrypicked) studies by other researchers.
    I offer a hypotesis to study for Dr. Chalker-Scott: Amending planting holes in a pure white sand with peat and manure gives at least 10 times larger harvest of black currants 5 years after planting, compared to unamended control, if the annual care is only watering according to need, and fertilizing once a year, both amended and unamended plots at similar rate.
    If Dr. Chalker-Scott will not agree to study this hypothesis, then I can do and document this experiment by myself, just to myth-bust her myth-busting about amendments in the planting hole.
     
    Last edited: Jul 31, 2020
  21. Margot

    Margot Generous Contributor

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    Dr. LC-S has never said anything to the effect that we should NEVER amend the soil when planting shrubs and trees. In fact, she has said the opposite.

    In the Myths of Soil Amendments Part 1, she summarizes her findings: https://s3.wp.wsu.edu/uploads/sites/403/2015/03/soil-amendments.pdf

    Bottom line:
    • Select suitable plant species for site conditions
    • Don't be an "enabler": use native soils for backfill without amendment
    In extreme cases, replace the entire planting site with topsoil
    • Mulch landscapes well with wood chips or another water-holding material


    I think Linda Chalker-Scott would agree that pure sand would be an extreme case.
     
  22. Sulev

    Sulev Active Member

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    I think, that because English is my 3rd language, then I may have difficulties with understanding, what this red text means, but according to my understanding this means, that instead of amending planting holes only, that my hypothesis is planning to do and what about Dr Chalker-Scott's myth-busting is talking, this red text means, that you replace the whole topsoil layer of the site, not only amend soil in the planting hole. Am I wrong?
    I stick with amending planting hole only, according to the myth. I don't want to prove effect of replacing the whole topsoil layer, but only effects of amending planting hole.

    If Dr. Chalker Scott wants, she may add replacing the whole topsoil to the test. My prognosis is that replacing the whole top soil will not improve the harvest compared to amended plots more than twice, provided that the amended planting hole is large enough (at least 60 cm in depth and at least 1.5 metres in diameter).
     
    Last edited: Jul 31, 2020
  23. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    Dr. Chalker-Scott's article, The Myth of Drainage Material in Container Plantings, addresses the specific issue of adding a layer of rocks with the intent on improving drainage. Its tag line is "Add a layer of gravel or other coarse material in the bottom of containers to improve drainage". A layer of rocks also allows one to make use of an oversized container for planting but then that is a different application altogether. The existence of different applications does not invalidate the findings presented in the article.
     
  24. Margot

    Margot Generous Contributor

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    I'm not 100% sure I understand what you mean so I hope this helps . . . my interpretation of Linda's 3rd point is that a generous amount of the native soil should be replaced by a more appropriate soil for the shrub/tree you want to plant. The size of the entire planting site might be too large (and too expensive) to replace completely but you'd want to be sure that there would be enough soil to keep the plant healthy for many years. Really - there's no alternative is there?

    Because there is so little soil in the area where I live, many gardeners bring in truckloads of fabricated topsoil to add another 12 inches or so on top of what is already in their gardens. (Some add much more than that.) I do my best to choose plants that can handle what the native conditions have to offer but, occasionally, I dig a really big hole and fill it completely with a special soil mix if I want to plant something that needs it to thrive.

    Another bit of advice that LC-S gives is to mulch the soil deeply around the tree or shrub. There are so many benefits with arborist wood chips in particular. If you're interested, see: https://s3.wp.wsu.edu/uploads/sites/403/2015/03/wood-chips.pdf
     
  25. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

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    Hear, hear.
     
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