Growing plants like HC and glosso without adding nutrients

Discussion in 'Aquarium Fert Dosing' started by Moss Man, 31 Oct 2007.

  1. Moss Man

    Moss Man Member

    Messages:
    89
    Location:
    Kent, UK
    Is it possible to have a 'high-tech' setup which you are able to grow demanding plants such as HC, Glossostigma and C. helferi with only supplying nutrients from tap water and a nutritious substrate.?

    Whenever people grow plants like HC, although sometimes we don't add macro nutrients (like Nitrate, phosphate) most of the time we add the micro-nutrients. It seems that plants like this enjoy a nutrient rich water column as well as substrate.

    If you had good CO2 and lighting but just a nutritious substrate what succes could you have growing plants?

    Do most substrates have all the available micro nutrients in them, or do plants need additional nutrients?

    Cheers,
    Mike
     
  2. daniel19831123

    daniel19831123 Member

    Messages:
    736
    Location:
    Blackpool
    I'm actually trying this at the moment. I'm setting up a natural tank with soil as substrate, no CO2 injection but with plenty of light >3wpg because of the tank is not anywhere close to the window. I'm trying to see if I can get away with not having algae in my tank.
    Just ordered some pogostemon helferi, HC, crypt balansae, and bolbitis heudelotii from germany. Will also get some pogostemon stellatus, and java fern narrow leave. Hopefully there will be enough rooted fast growing plant in the tank to compete with algae. And if Diana Walstad is right about the amount of DOC in the tank using soil as substrate, I might get away with not injecting CO2
     
  3. George Farmer

    George Farmer Founder Staff Member

    Messages:
    7,089
    Location:
    Cambridgeshire
    It is possible to have success via sediment only nutrients. Jeff Walmsley's set-ups do this, although he does admit to getting algae regularly. He does dose CO2 though, at low levels.

    You will have trouble with more demanding plants though, as the higher lighting required means that CO2 injection is necessary.

    >3wpg is asking for algae with no CO2 in anything over a 15 gal.
     
  4. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,937
    Location:
    Chicago, USA
    Hi guys,
    Here is a way I like to think about it (another cheesy analogy). Say I'm thirsty and I have a pint of beer in front of me. I could use a straw or even two or three straws and slurp like crazy to consume the beer, or I could toss the straws and down the beer directly. Which way is faster? I think I saw a program on the tele where some guy was able to down a pint in under 3 seconds. Bottoms up!

    This is the difference between root feeding (straw) and water column feeding. Ideally it's always good to have both available but if you're stuck in the desert, and the sun is shining and you're offered a glass of water, which method would you use to drink it? The straw method cannot slack thirst fast enough.

    High light compels the plant to uptake nutrients at a very high rate. They have no choice - it's strictly a photochemical reaction. It's very difficult for this uptake demand to be satisfied by the roots alone because the mechanism by which nutrients are pulled in and distributed by the roots is too slow. The plant then suffers nutrient deficiency because it cannot supply its requirements at the rate that photosynthesis is being driven by the intensity of the light.

    Think also about the distance that the nutrients must travel from the root all the way up to whatever reaction chambers they are needed in at the leaf or stem. With water column feeding the distance is almost nil, only across the cell walls to the site where it will be used.

    If you intend to rely solely on root feeding while driving the plants with high lights you are imposing a greater degree of difficulty on the plants than is really necessary.

    Cheers,
     
  5. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    I don't quite understand the thrust of your arguement here Clive. Plant roots are the primary method for most plants to access nutrients and as, as far as I am aware, all aquatic plants are terrestrial in evolutionary origin and are surely therefore mainly the same. Plant roots are superbly designed to extract nutrients against a concentration gradient via complex interactions with their environment and the ionic concentrations of their cells. The phosphlipid bi-layer of their cells even have a higher percentage of molecules that can perform active uptake too.

    As far as I understand from a bio-chemical point of view, water column dosing is the equivalent of foliar feeding for terrestrial plants; something that can produce great results but only with very regular applications, but is never more effective than optimum root fertilsation as hydroponic cultivation shows. As you infer, IMHO quite rightly, if you were really driving things hard then you may need to supplement the substrate feeding, but you should, in theory, be able to boost the nutrient levels of the substrate and get similar results too.

    As to your analogy of strawa, surely another interpretation could be that roots may be the equivalent of many straws, but surely foliar assimilation is the equivalent of trying to soak the beer up through the skin!

    After all ADA Amazonia is a effectively a high nutrient substrate that uses relatively lean water column and plants seem to do great with that! Just not sure you could achieve those results with a soil substrate.
     
  6. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,937
    Location:
    Chicago, USA
    Hi Ed,
    Yes, aquatic plants are terrestrial in origin and in fact, in the emersed state function as terrestrial plants but there are some adaptations that allow them to function efficiently submersed. It's difficult to compare behavior and efficiency in each state simply because of the different media. One example is that terrestrial plants have pores (stomata) distributed on the leaves by which they are able to absorb CO2 directly. These pores also allow evaporation at the leaf surface which facilitates, by capillary action movement of water and nutrients to be drawn up through the roots to the leaf. This is a powerful hydraulic force which enables tons of water to be lifted from deep in the soil to several stories the top of a massive oak tree. Capillary action in air works tremendously more efficiently then in water, where as you point out, the uptake mechanism is via osmotic pressure and concentration gradients.

    Since a submersed aquatic plant has no pores, osmotic pressure and concentration gradients work to its advantage across the leaf structure directly as well as through the roots but is more effective through the leaf, if for no other reason the small distance to the destination chambers. The structure of the submersed leaf is really quite a bit different than that of it's terrestrial counterpart and that's one of the reasons that the submersed form of many aquatic plants are completely unrecognizable from their terrestrial form.

    Through their basic rigid structure and through the opening and closing of the pores, terrestrial leaves are designed to modulate water transfer across the membrane depending on ambient conditions, so yes, applying nutrient mist on a terrestrial leaf is analogous to skin absorption, but a nutrient transfer across a submersed leaf form is a completely different story.

    Apart from the scientific principles, the empirical evidence shows for example that it is possible to achieve nearly maximum growth rates with aquatic plants grown in inert sand and applying water column dosing only. I don't think that would be possible if aquatic leaves were as inefficient as the foliar feeding (or skin absorption as you say) in terrestrial plants.

    I agree that theoretically, imbuing the soil with additional nutrients should boost plant growth, but isn't that what root tabs are supposed to do? I just don't think that they work as well as just adding more nutrients to the water column, so there is a practical element to my cheesy analogy. :)

    I also totally agree that it's much better to have both a nutritious soil as well as water column dosing for maximum efficiency, however I think, based on the Barr experiments, that as the lighting is pushed upwards, water column dosing to supplement the basic substrate feeding would have a better yield that solely boosting the level of nutrients in the substrate.

    Cheers,
     
  7. Maximumbob

    Maximumbob Member

    Messages:
    119
    Location:
    Cheshire, UK
    This is a very interesting thread, and I am surprised that I have an observation to make.

    I think that my basic understanding is that roots are the best at transporting nutrients... thats their job. However, foliage can do this also, and the plant can adapt to do this even more.

    At this stage I would still say roots win BUT then comes the mechanics etc.

    In water column fert dosing the properties and flow of the water facilitate excellent exchange and diffusion. The soil and roots don't benefit from this advantage to the same degree.

    I think its a case of specialisation of plant structure versus adaptive changes in an advantageous environment. As to which is better... i dont know :)

    Hope this makes sense....
     
  8. beeky

    beeky Member

    Messages:
    879
    Location:
    Chippenham, Wiltshire
    Didn't Zig show this in his award winning tank where only horticultural grit was used as the substrate?

    Mind you, that's the opposite of what we started out with - the growth of plants with a lean water column. In nature, how abundant are nutrients in the water? I assume these are lean as well, but have a nutrient rich river bed (laterite etc).
     
  9. Ray

    Ray Member

    Messages:
    474
    Location:
    Switzerland
    Lovely debate, nice thread. All I can add is that Barr does cite a study whereby they cut all the roots off the plants and growth is the same. This suggests that on aquatic plants the roots are there as an anchor and for capiliary action when the plant finds itself emersed.
     

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