Opinions for root tabs

[zozo]

Osmocote® is patented... Made by ICL.

About ICL

But there are trademarks such as Pokon, Substral, Miraclegrow and many others any country has its own tradenames going around that sell the Osmocote pellets or cones licenced under their own name and do not always (need to) reveal it actually is Osmocote.

Anyway if you see this product in a bag or a jar, whatever name is on it, it actually is Osmocote®.

Aquatic Plant Fertiliser

Aquatic Plant FertiliserOsmocote slow release fertiliser comes in easy to use cone shaped tablets that you simply push into the soil. By feeding your aquatic plants this way it ensures you give each plant receives an exact dose and the fertiliser is contained within the soil, making application...

plantsforponds.co.uk

 

[Luciën]

Why do people add root tabs at startup? I just started a new tank and had a big jar of osmocote by hand, but I did not add them as I thought there would be enough ferts in the aquasoil for the first months.. It makes more sense to add root tabs later on imo.

 

[Regent]

I used them under the swords and Lilly and have always seen a response...
Found a couple of interesting papers on temp and water column release from a sand bed:

The second one is more relevant as it covers newer generation products
www.plantgrower.org › etdPDF Influence of Temperature and Time on Nutrient Release Patterns

Macro‐and micronutrient‐release characteristics of three polymer‐coated fertilizers: Theory and measurements

It certainly doesn't appear that at 20deg it's all dumped into the water at once..
Personally I think there's merit in direct root feeding.

 

[dw1305]

Hi all,

It certainly doesn't appear that at 20deg it's all dumped into the water at once..

That is a useful reference.

....... Contrary to several studies, our data and model indicate that there is no significant difference in nutrient-release rates in water and amoist, solid substrate. This means that release rates determined in water can be used to modelbio-available nutrient concentrations in moist soil or soilless media where sorption/desorptionproperties alter concentrations after release. Across all PCF, the nutrients most affected by tem-perature were typically N, K, B, Cu, and Zn, while the least affected were P, Mg, and Fe..........

(1) (PDF) Macro‐and micronutrient‐release characteristics of three polymer‐coated fertilizers: Theory and measurements. Available from: (PDF) Macro‐and micronutrient‐release characteristics of three polymer‐coated fertilizers: Theory and measurements [accessed Jan 04 2021].

cheers Darrel

 

[Regent]

I also found it interesting the difference rates of release from the different polymer coatings. They're not all the same thing! Some of the exact ranges have release graphs on the website.
The graphs in the paper also raise the question if it's worth washing/soaking the osmocote to wash out the initial rapid release and get to a steady state.

I wish I had the kit to measure these things.

 

[Simon Cole]

Hi @dw1305 - sorry to bother you. I noticed that "blue loam" is used in some aquatic composts like Velda Lelite. I suspect that it is very heavily reduced, and probably a gley of some sort. You made an interesting point above:

There can still be some issues, the red colour is iron, but it is in the form of hydrated ferric oxide (Fe(III)O2, "rust"), so it isn't plant available all the time the <"substrate is aerobic">,

Would you favour a reduced or oxidised substrate?

Many thanks, and hoping you are well

 

[dw1305]

Hi all,

I noticed that "blue loam" is used in some aquatic composts like Velda Lelite. I suspect that it is very heavily reduced, and probably a gley of some sort.

I would guess you are right, a <"London Clay"> or similar.

Because <"Velda Lelite"> has been specifically designed for Water Lilies it will be slightly different from an ideal tank substrate, in terms of nutrient content and physical structure. Water lilies are big and chunky and have access to atmospheric oxygen, <"via their floating leaves">. This is combined with a <"high nutrient requirement"> and <"rhizome architecture"> that allows them to efficiently export oxygen to the rhizosphere. This is Nelumbo, rather than Nymphaea, but I think they <"would be pretty similar">.

Would you favour a reduced or oxidised substrate?

<"I use sand">, but that is mainly because <"I want low nutrient levels">. I tend to leave the substrate undisturbed and all my tanks are long term set-ups, so I would imagine they become <"more soil like over time"> and that they would develop areas that are anaerobic and reducing.

That would really be what I'm after, a substrate with patchy areas of fluctuating REDOX as <"roots grow and senesce">. I know that plant and invertebrate biodiversity is enhanced in patchy environments (<"temporal and spatial mosaics">) and I would be very surprised if the same wasn't true of the microbial flora in the substrate.

cheers Darrel

 

[Simon Cole]

Fantastic advice @dw1305 Thank you