Making a terrestrial foliar feed from Tropica premium

[Simon Cole]

Hello my friends,

I have been working with organic composts this year, and I have diagnosed a immobile micro-nutrient deficiency across a polytunnel.
The problem is due to an incredibly high phosphorous load recorded in the compost and plant tissue. This has bound up one of the immobile nutrients in the soil but we are not sure which one. The head gardener used bat poo. I have leached most of the phosphate out now, and I dosed with calcium and magnesium (also as foliar application): It made no difference. I am therefore confident through the power of deduction that it will be something like Zn or S. The mix also contained a lot of peat so we don't have an ideal buffering capacity.

I cannot find a decent trace mix locally and Royal Mail are consistently taking up to two weeks to deliver 1st class post where we are working, never less than 7 days. The only thing we could get hold of was Tropica premium, which looked ideal to make into a foliar spray.

I have read in places that foliar sprays need to be several times the concentration of root feeds. I know that aquatic fertilisers like Tropica can be a little bit light.

Any recommendations for the dilution factor?
Also, how long does that stuff last on a shop shelf?

- It is a clear bottle and must have been exposed to UV - which I know is bad for iron stability - what about Zn, Mg and S?

Glad that this post is a little bit off piste for once

 

[jaypeecee]

Hi @Simon Cole

Good to 'see' you again. I can't answer your question but if I mention @dw1305 right here, he may get a notification. I seem to recall that Darrel has worked in commercial horticulture in the past.

JPC

 

[Simon Cole]

Thanks John. I was going to ask Darrel but I'm always impressed by the knowledge shared by the society, I guessed he might be quite busy teaching. Fingers crossed.

 

[LondonDragon]

@Mick.Dk might be able to shed some light also

 

[Simon Cole]

Fingers crossed for Mick too
I know it is a very difficult question - not many people on my team knew - I will ask tomorrow next door at the organic gardens. I think they want it all to be organic, so I don't know how I'm going to get around this one. I just cannot face the uncertainly of using seaweed extract compared to what we aquarists do. Organic aquarium fertilisers = now that I would call unfeasible.

 

[PARAGUAY]

Also they may help TNC drop a email

 

[dw1305]

Hi all,

I seem to recall that Darrel has worked in commercial horticulture in the past.

I did, <"but a long time ago">.

...I guessed he might be quite busy teaching.

Last week of (virtual) term, so busy with a lot of meetings.

I'm always impressed by the knowledge shared by the society

I have a pretty laissez faire attitude towards fertilisers and fertilising, but we have a lot of members who have approached it in a much more scientific and rigorous manner.

I have leached most of the phosphate out now

My guess is that it will still be a large reservoir of PO4, it is really strongly bound to humus and clay, and <"difficult to remove">

The head gardener used bat poo.

I think that makes a micro-nutrient deficiency more unlikely, insects are pretty rich in most micro-elements and <"so is bat guano">.

I have read in places that foliar sprays need to be several times the concentration of root feeds

Usually the same fertiliser rate as you would use <"for liquid feed">.

The only thing we could get hold of was Tropica premium, which looked ideal to make into a foliar spray.

Should be fine, it will be a bit light on nitrogen.

Personally I would go down the <"Miracle-Gro route">, at ~£5 for kilogram you re going to get a lot more <"bang for your buck">.

cheers Darrel

 

[Simon Cole]

Bingo - slight chance now that we have the culprit. I will anticipate S deficiency - not in bat poo. That was in the polytunnel with a better vapour-pressure deficit (VPD). If this fails then it's phosphate leaching time
On a side note, the other tunnel had very low humidity (poor VPD) and we have all the classic signs of nutrient issues. They built the darn thing with net sides so it makes leaf-nutrient control almost impossible.
Cheers Darrel. All those years of your research have paid off. Hopefully you have helped to feed the "community" down on the project right in the middle of lock-down. Thank you.

 

[Simon Cole]

I think I've cracked it. All of the plants are recovering after using a slightly elevated dose of Tropica Premium as foliar feed and root irrigation. Unlike other formulas it includes both S and Mg. Seems to be an ideal quick fix.

I also noticed that this cheap kit off ebay looks largely identical to Solufeed Sodium Free TEC™ and they have dosing instructions for all types of irrigation systems, including foliar. I'm not sure what the optimal dosing of trace elements would be for different aquatic plants, and I cannot find any info about this within the EI framework, but I suspect that trace element optimisation could be the key to growing certain more problematic aquatic species.