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Potassium uptake via substrates

Discussion in 'Advanced Strategies and Fertilization' started by Martin, Dec 23, 2008.

  1. Martin

    Martin Lifetime Charter Member
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    Hi.

    A discussion has come up on my site about substrates, clay, not clay, etc etc.

    Now 1 point came up, that the roots of submerged macrophytes does not uptake Potassium.
    I've only been able to find 1 souce for this information, a Book by Peter Hiscock called 'Aquarium Plants'.

    Has anyone else experienced this? or have reference to other documentation?
     
  2. Tom Barr

    Tom Barr Founder
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    Barko et al did a lot on this topic. Barko and smart did quite a bit of research in the 1980's. He concluded that plants do not take it up from the sediment. But I bet they can if forced to, like every terrestrial plant.

    CSA

    Please be careful when reading it.
    There are important things in there to consider also, these are what is found in natural systems and in test where they gave these specific plants certain conditions.

    Most of these plants are "weeds" in the worst ways. They may not represent the 300-400 species we keep.

    It says that most plants get the N and P from the sediment, however they can and do get them as well from either the water column or the sediment, eg, they are "opportunistic", I see no reason why this would not apply to K+ as well in the sediments.

    An important thing he mentions also is about % organic matter(OM%): high OM s bad, low to moderate % OM is good, fine textured sediment, eg clays...........are good. Sands tend to be too infertilie, heavy peats are too fertilize and reductive.

    So sediments need fluffed up over time(1x every year or two seems good and done in 20-33% sections per week etc). They buil,d up too much mulm(OM).
    New sediments like plain sand do not have enough mulm(OM), so we can add it or add some soil, clay etc.

    ADA is good since it has some nutrients as well as good texture and OM%.
    It is not much different than the clays we have out in the delta here.

    Here is a good review that is open source:
    Not a bad read for everyone anyways:D

    http://www.apms.org/japm/vol24/v24p1.pdf

    You will note he mentions that K+ can be used from the sediment, but in experiments, adding K+ to the water column enhanced growth.

    He also hints at ion selection in the roots, but think about this in the water column with respect to K+ and NH4. Does K+ in the water column compete for NH4 leaf uptake?

    No one has looked at that.

    Here's the specific K+ reference many cite, but it's for one plant species,
    CSA

    I'd suggets reading the pdf instead and using that as a more general view on aquatic plant research. You still need to understand it's what is found in natural systems etc, where changing CO2, light are generally not possible.

    Here's some work from Madsen and Cedergree from your side of the Pond so to speak:

    Wiley InterScience :: Session Cookies

    They compared several senarios and plant species.

    This paper is good work on allocation of resources and nutrients.
    We discussed it here on campus in a presentation I did.
    It was well recieved amongst a large group of professors and grad studnts.
    Give that pdf a good read, it's not too "techy" reading with lots of jargon either.



    Regards,
    Tom Barr
     
  3. Martin

    Martin Lifetime Charter Member
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    Hi Tom.

    Thanks for the fulfilling post.

    sadly, only 1 of the 4 links are actually working.. (the PDF) the 2 CSA need a login, and the Wiley interscience doesn't work. link is bad.. :(
     
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