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Good paper on fertilizing aquatic plants for research.

Discussion in 'Aquatic Plant Fertilization' started by Tom Barr, Sep 3, 2009.

  1. Tom Barr

    Tom Barr Founder
    Staff Member Administrator

    Jan 23, 2005
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    8:34 AM

    You will note Osmocoat being used, Hoagland's solution etc.
    Sediment injection etc.

    Can you think of a problem injecting a concentrated brine salt solution into the root zone at high concentrations 3x a week?
    What might that do to plant growth vs say adding only a tiny amount? When we add ferts to the aquarium, we add them to the entire aquarium, not just the root zone.

    Thus they are far more diluted.
    Hoalglands using only KNO3(not any NH4) at about 1/5 th concentration we suggested by Gerloff in the 1960's.


    Tom Barr
  2. Solcielo lawrencia

    Mar 20, 2013
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    Local Time:
    8:34 AM
    A quick summary of the nutrient injection article:
    There were two culture periods conducted back to back.
    1st culture period (Sept-Nov, aka autumn) shows the greatest growth of shoots and roots with little or no tubers.
    2nd culture period (Nov-Jan, aka winter) shows the least growth of shoots and roots but with the greatest number of tubers except for the Vigoro.

    In both periods, an N:p ratio of ~1:1 resulted in the greatest growth while the N:p ratio of ~ 5:1 resulted in the least.

    So why did the Hoagland's N:p ratio of ~1:1 result in the greatest growth? And an N:p ratio of ~5:1 result in the least?
    Osmotoxicity? Might also be clogging the roots so it prevents uptake. "When hydrilla plants were injected with Hoagland's nutrient solution which resulted in a total of 4500 mg of nitrogen... roots at time of harvest were heavily encrusted with a salt-appearing material." (67-8) Was that salt-appearing substance KNO[SUB]3[/SUB]?

    The Osmocote and Vigoro are slow-release fertilizers which had the greatest growth compared to the Hoagland's solution. However, the amount that would have been released in just 8 weeks would be far less than the solution injection. According to the footnote on p.66, the Osmocote had an 8-9 month release time. It contained 4500mg of N. So for the two month culture period, about 1000mg of N were released. This correlates closely with the maximum growth where 750mg of N resulted in the greatest amount of growth.

    I also wonder why the Vigoro, which contained a high amount of P (3273mg), didn't grow H. verticillata as well as the Osmocote with far less (654mg). No tubers were formed in either growth period while Osmocote produced 8 tubers during the winter period.

    The link doesn't work.:p

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