Plant Nutrient Intake

[John P Coates]

Hi Folks,

I would like to better understand the mechanisms by which aquatic plants take in nutrients. Firstly, are aquatic plants equally able to absorb nutrients through their roots and leaves? Which of these do they prefer? Some plants, e.g. Anubias, are normally grown on driftwood or rocks but presumably they take in nutrients through their aerial roots as well as leaves?

Since most fertilizers appear to be added to the water column, what part does the substrate play other than anchoring/physically supporting the plant? Is it necessary to use specialist substrates such as Tetra Complete?

In their natural habitat, do aquatic plants get nutrients from the substrate or from the water in which they grow?

Perhaps someone could point me to some reading material where I could get a handle on this important topic.

Thanks in advance.

JPC

NOTE FOR ADMIN : I wasn't sure which was the most appropriate forum to plant (pun intended!) this thread in as it covers ferts, substrates, plants. Please move this thread elsewhere if deemed necessary (but preferably not to the recycle bin!). Also, I used the word 'intake' but perhaps 'uptake' would have been a better choice.

 

[dw1305]

Hi all,

I would like to better understand the mechanisms by which aquatic plants take in nutrients. Firstly, are aquatic plants equally able to absorb nutrients through their roots and leaves? Which of these do they prefer? Some plants, e.g. Anubias, are normally grown on driftwood or rocks but presumably they take in nutrients through their aerial roots as well as leaves

All plants can take in nutrients through their leaves. Whether the mode of uptake is through foliar feeding, or via the roots in the substrate, the nutrients are only available to the plant when they are in solution as ions.

There is a bit more here: <http://www.ukaps.org/forum/threads/plant-roots.24143/#post-247542>

Since most fertilizers appear to be added to the water column, what part does the substrate play other than anchoring/physically supporting the plant? Is it necessary to use specialist substrates such as Tetra Complete?

The substrate has a role to play beyond purely physical anchoring. Clay and humus based substrates have the ability to retain and exchange ions, we call this CEC for the cations and AEC for anions. Have a look at Clive's post here
<http://www.ukaps.org/forum/threads/flora-max-v-eco-complete.13801/#post-143731>

There is a good review of substrates: <http://www.skepticalaquarist.com/substrate> at the excellent
<Skeptical Aquarist>.

cheers Darrel

 

[John P Coates]

Hi Darrel,

I really appreciate your reply and some good links. Thank you!

JPC

 

[Marcel G]

There is an article here: http://www.prirodni-akvarium.cz/index.php?id=substrat-vs-pisek, which deals with a similar question as you have → wheather the nutrient-rich substrate is better then inert gravel? It's in czech (so use Google Translate) ... but there are links to a few studies on this topic.

 

[John P Coates]

It appears that not all plants absorb nutrients equally. The E. bleheri and H. guianensis have received similar PAR and CO2 from the day they were planted in my tank. What's more, the Sword has been in the tank for a couple of months longer than the H. guianensis. Is there a possible problem with only adding ferts to the water column as the hungriest plants deprive other plants of nutrients? As such, does this not make a case for supplementing with root fertilizers - both macro and micronutrients? Or am I barking up the wrong tree?

JPC

 

[John P Coates]

Hi Folks,

Does anyone have a view on my last question? It would be good to get some feedback.

JPC

 

[ceg4048]

It appears that not all plants absorb nutrients equally.

Correct. Also, not all plants are capable of the same CO2 uptake rate. Just like not all people eat the same amount or grow at the same rate.

Is there a possible problem with only adding ferts to the water column as the hungriest plants deprive other plants of nutrients?

This possibility can be discarded if the plant shows no signs of nutrient deficiency. There are possible problems with the hobbyist who fears to dose the water column however. This happens all the time. Another possible problem is that the hobbyist assumes that two plants in the same tank should have the same metabolism and nutrient/CO2 uptake and processing ability. If that occurs then expectations may be unrealistic.

As such, does this not make a case for supplementing with root fertilizers - both macro and micronutrients? Or am I barking up the wrong tree?

Eutrophic dosing of the water column adds more nutrients than can be assimilated by the plants in the tank. However there is nothing wrong with adding nutrients to whatever location desired. It's a good policy, especially if the conditions in the tank create a high nutrient demand. If that's the case it is useful to use a fortified substrate such as Amazonia, or to use a more general addition to the bottom of the substrate to account for missed dosing days. This includes, but is not limited to root tabs.


I never use root tabs and I have never experienced difficulty growing Echinodorus in inert sediments. In fact they grow so quickly they become nuisances which inevitably have to be forcibly evicted from the tank. Anyone who assumes root tabs are a better option than water column dosing for high growth rates of large rooted plants is living in a dream world.






Cheers,

 

[roadmaster]

I think Clive may have answered this in one of the links provided.
Ideally, Plant's could draw nutrient's from both the sediment and the water column.
For me,,I try to create a sediment that is beneficial to the roots of such plants as echinodorus and crytpts among others and I also dose the water column.
I am near certain that some plants are greedier than others.

OOPS!
Clive beat me to the point.

 

[John P Coates]

This possibility can be discarded if the plant shows no signs of nutrient deficiency.

If that's the case it is useful to use a fortified substrate such as Amazonia, or to use a more general addition to the bottom of the substrate to account for missed dosing days. This includes, but is not limited to root tabs.

Hi,

Unfortunately, my E. bleheri is definitely showing signs of nutrient deficiency and, disappointingly, this has worsened since I upped the dosage of liquid ferts containing both macro and micronutrients (Tropica Specialised Fertiliser). Indeed, the E. bleheri is not alone. My Pogostemon helferi is also suffering. So, yesterday, I started an experiment. I have added a TNC root plug at the base of each of these two plants. If they start to grow healthily, I will be hesitant to rely purely on liquid fert dosing in future. The H. guianensis in my tank is growing prolifically. My hunch is that it is swallowing up virtually all the liquid ferts that I add to the tank. That's why I wanted to try the root tab. The TNC root plug contains both macro and micronutrients.

I use Tetra Eco Complete for the base layer topped with JBL Manado. I have seen one of your comments about the Tetra product and I agree - it is far from complete. When I purchased it, I knew it did not contain nitrates or phosphates but I'm now seriously wondering what it does contain! I take it that Amazonia would have been a better choice.

JPC