Of Vermicompost teas.

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Stone

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But I Know that EC meter is not very usefull for organic fertilizer ....
It will not measure organic Nitrogen but there will not be too much left in vermi tea? But you should still use it to give you some idea how strong the soluble minerals are now.
 

Stone

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Thanks for reminding me! I haven't looked at it for months :eek: It's probably all dried out now:sob:
It was going along ok last time I looked. I wanted to get nice pure castings before I used it (with takes quite some time!) I'll let you know what I find.
 

naoki

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That's too bad. I started it right after you brought this up. I'm getting ready to harvest within the next month. The composting process works much better than I expected!
 

Stone

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Warning! Thread resurrection!

Well I've been using the vermicompost tea for about 3 months now (about once per week as a drench and twice a week as a spray) So far I have not noticed any negative effects. On the plants in clear plastic pots. There are pretty good clean white root tips on many plants including brachypetalum. I have also used it on de-flasked seedlings and again, no problems with disease on leaves or roots so far. I'm confident there is suppression of pathogens.
The compost is now devoid of worms. I don't know whether they died or escaped. The material is very fine and humified. No smell whatsoever and it's more than 18 months old.
 

myxodex

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Well I've been using the vermicompost tea for about 3 months now (about once per week as a drench and twice a week as a spray) So far I have not noticed any negative effects. On the plants in clear plastic pots. There are pretty good clean white root tips on many plants including brachypetalum. I have also used it on de-flasked seedlings and again, no problems with disease on leaves or roots so far. I'm confident there is suppression of pathogens.
The compost is now devoid of worms. I don't know whether they died or escaped. The material is very fine and humified. No smell whatsoever and it's more than 18 months old.
Good to know it is working with orchids.

I was thinking of experimenting with vermicompost tea (VCT) having got the wormery back up and running. I have sifted through a bunch of literature on this to get some ideas on what works best and why. What I found was quite a bit of variability in reports , ... but there are a few things that might be of interest to those experimenting with this.

1) VCT's do typically contain a number of known plant beneficial microbes and adding a carbon source to the brew helps increase the bacterial content. The choice of carbon source could be important. So adding sugars, e.g. molasses, doesn't preserve the bacterial diversity as well as more complex carbon sources do. Quite a few beneficial bacteria are known to produce glucanases and/or chitinases. Some folk have used oat bran (a source of glucan). I've thought of combining a glucan with colloidal chitin as a carbon source to help the survival of bacteria in the actinomycetes section. Most known chitinase producing bacteria come from this section. Actinomycetes and related bacteria are of major importance in most terestrial ecosystems with high organic matter turn over, but they are slow growing and can be swamped out by faster growing opportunistic bacteria when sugars are provided. There is some evidence that complex carbohydrates and longer brewing times are better than the molasses recipe most often suggested.

2) One study used a combination of seaweed extract and humic acid to supplement the brew. They got good results with growth promotion but it is not clear whether it's the phytohormones in the seaweed or those produced from the bacteria in the brew. Other reports indicate that humic acid can bind and stabilise phytohormones in a composting enviroment in which they are otherwise destroyed quite quickly, and can act as a slow release system for these. Humates are present in VCT to a greater or lesser extent anyway, but it seems adding some seems to be beneficial in stabilising the phytohormone effect.

3) Aerated teas (ACT) versus nonaerated teas (NCT) at suppressing fungal pathogens in seedlings when used as a drench or foliar spray. Some reports say that ACT are better at suppressing fungal pathogens whilst others find NCT work just as well or even better. Another study found that the biggest factor was the compost sample used to make the tea. If anything teas made from various animal manures seem to outperform vermicomposts in this department.

4) One thing that bothered me a bit was that ACT tend to end up with a higher pH (>= 7.5) than NCT although there were some exceptions to this. You may want to check the pH of the final brew as some can end up with pHs in 8 - 9 range. Furthermore diluting the tea too much has been shown in some studies to completely eliminate any beneficial effect. This makes me wonder whether the whole benefit of vermicomposting is all down to phytohormone content more than it is about providing beneficial bacteria ... and it was the latter possibility that got my interest in the first place.
 

Ray

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In support of item 2, kelp is a major nutrient in the production of Inocucor's product.
 

Stone

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VCT's do typically contain a number of known plant beneficial microbes and adding a carbon source to the brew helps increase the bacterial content. The choice of carbon source could be important. So adding sugars, e.g. molasses, doesn't preserve the bacterial diversity as well as more complex carbon sources do. Quite a few beneficial bacteria are known to produce glucanases and/or chitinases. Some folk have used oat bran (a source of glucan).
That's interesting. I have used molasses as a supplement to the tea but I'm still in two minds as to whether it is of benefit or not. From what you say perhaps it's best left out? Are they adding the oat bran into the compost or after extraction?
I did read one paper where they found good suppression of root-knot nematodes (aerated pig manure VCT I think). Chitin is part of the nematode's structure and adding chitin in the form of crushed crab shells apparently results in an increase of chitin digesting bacteria which also suppresses the nematodes so I can see how that ties in with the VCT.

I've thought of combining a glucan with colloidal chitin as a carbon source to help the survival of bacteria in the actinomycetes section. Most known chitinase producing bacteria come from this section. Actinomycetes and related bacteria are of major importance in most terestrial ecosystems with high organic matter turn over, but they are slow growing and can be swamped out by faster growing opportunistic bacteria when sugars are provided. There is some evidence that complex carbohydrates and longer brewing times are better than the molasses recipe most often suggested.
What other forms of complex carbs could be added to the brew?

2) One study used a combination of seaweed extract and humic acid to supplement the brew. They got good results with growth promotion but it is not clear whether it's the phytohormones in the seaweed or those produced from the bacteria in the brew. Other reports indicate that humic acid can bind and stabilise phytohormones in a composting enviroment in which they are otherwise destroyed quite quickly, and can act as a slow release system for these. Humates are present in VCT to a greater or lesser extent anyway, but it seems adding some seems to be beneficial in stabilising the phytohormone effect.
Yes, as you say humic acids are present in the VCT. I think this probably depends on the materials used and or the time given for maturity (the fineness of the final product. I have read that naturally derived (or occurring) humates out-performed commercial preparations. Brown coal may be one potential source that can be added to the worm farm to boost these?

If anything teas made from various animal manures seem to outperform vermicomposts in this department.
In most of the literature I've read they used composted animal manures to start the vermicompost. These outperformed other VCT made from garden refuse and leaves etc. From what I remember there was a big difference in the nutrient value between the two. Especially nitrate vs ammonium, but probably also more concentrated in micro nutrients as well due to the materials fed to the animals.

4) One thing that bothered me a bit was that ACT tend to end up with a higher pH (>= 7.5) than NCT although there were some exceptions to this. You may want to check the pH of the final brew as some can end up with pHs in 8 - 9 range.
I did aerate my first few batches but no longer bother. I also read conflicting results from aerated v non-aerated. One thing of interest was the difference in bacterial and fungal species with the time used for brewing. Apparently there are some microbes which are easily separated from the substrate and others which cling much more tightly. Periodic agitation of the bag seems to be of benefit here. The pH of my final product is about 6. I did not add any lime at all. It's much easier to start with an acidic product and raise the pH if necessary later. Obviously the water used will make some difference. I have no idea why aerated tea should end up with a higher pH than non- aerated though.

Furthermore diluting the tea too much has been shown in some studies to completely eliminate any beneficial effect. This makes me wonder whether the whole benefit of vermicomposting is all down to phytohormone content more than it is about providing beneficial bacteria ... and it was the latter possibility that got my interest in the first place.
There seems to be enough evidence out there which attributes pathogen suppression (mildew, anthracnose, pythium etc) directly to microbial diversity and predation. When we add up the other benefits from pest suppression (aphid, mealybug, mite etc) nutrient content and availability, chemical growth factors (hormones, vitamins etc) along with pathogen inhibition, It could almost be viewed as the missing link between natural eco-systems and artificial cultivation if we can get it right.


PS, My compost was made up of the following: Dried Oak leaves, bamboo leaves, cow manure, some rotted hardwood and dried grass as a base. Soya bean meal, Canola meal, blood and bone and some seaweed extract.


Myxodex, have you read this one yet?
https://www.researchgate.net/profil...hoi_growth/links/09e4150f9c336493b6000000.pdf
 
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myxodex

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@ Mike, thanks for the useful information in your response. Also thanks for the link, I had scanned this paper but still need to read it carefully.

@ Ray, thanks for that information about kelp extract, I will certainly try some brews with it.

I was going to do a longer post but it seems I can no longer cut and paste from notepad, which I normally do to circumvent being timed out.

There is some very interesting stuff out there on PGPR's and I will get back about the experiments I'm planning.
 

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Very interesting read guys. I have never used VT on orchids but on various other crops it works very well. You say you have not noticed any negative effects, but is there any positive effects above and beyond your usual fertilizer regime prior to using VT?
I will say this ... if I have to drench once a week and spray twice a week, I don't care how good the product is that is an inefficient use of time, energy and money for a collection over 20 plants. Cost to benefit ratio is askew, and that is not factoring in time to make the tea.

Cheers
JAB
 

myxodex

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Very interesting read guys. I have never used VT on orchids but on various other crops it works very well. You say you have not noticed any negative effects, but is there any positive effects above and beyond your usual fertilizer regime prior to using VT?
I will say this ... if I have to drench once a week and spray twice a week, I don't care how good the product is that is an inefficient use of time, energy and money for a collection over 20 plants. Cost to benefit ratio is askew, and that is not factoring in time to make the tea.

Cheers
JAB
A very good question about the longevity of the benefit, for which I suspect we do not have an answer. I'm setting up to do some experiments with colloidal chitin, amorphous cellulose and possibly beta-glucan. Many of the protective PGPR's make extracellular enzymes to degrade these polysaccharides (PS) and I'm going to try these as the C-source in making the tea. I will then be able to test the tea for chitinase producers in the final VCT. If positive then adding a small amount of these PS's to the fert regime may help to keep the PGPR's going. The idea of feeding the PGPR's, not just the plant could be a bit crazy, but I've started making my own fert which contains both organic acids and amino acids and seen a slight improvement in growth. The limiting major nutrient for PGPR's will be a carbon source.

The problem is that there will be a microbial population in our pots anyway, and feeding them might only be a good thing if they happen to be beneficials or PGPR's. In particular feeding with PS could also encourage non-beneficial fungi which could inhibit the plant. That is why I'm after chitin degrading bacteria like some Pseudomonas and Bacillus species as some of these come with a number of beneficial activities as well as inhibiting fungal growth. It could all go horribly wrong, but I'm going to try anyway.
 

myxodex

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There is another aspect of the benefit of PGPR's that will be longer lasting and a clue to this, and why it might work with orchids, comes from results found with orchid propagation media. Supplementation of the seedling replate medium with 10 mg/L of chitosan (a souble derivative of chitin), makes the seedlings grow a bit faster, but the main benefit is that they are significantly more resistant to infection after deflasking.

Both chitosan and soluble chitin oligosaccharides are known to be elicitors of induced systemic resistance (ISR) in plants. A review by L.C. van Loon ( http://link.springer.com/article/10.1007/s10658-007-9165-1 ), explains ISR in some detail and how PGPR's can elicit ISR in plants. PGPR's that release or excrete molecules which mimic those produced by a pathogen can sometimes elicit ISR. Soluble chitin oligosaccharides would naturally be released if PGPR's are degrading chitin in the rhizosphere. So while the damage to fungal cell walls and the resulting inhibition of their growth by the chitinase/glucanase combination has been well documented, it may be only part of the resistance to pathogenic fungi provided, and ISR might play a role as well. ISR is quite interesting as it can sometimes extend resistance throughout the whole plant, not just the roots, and appears to be a general resistance not specific a particular class of pathogens. ISR is a relatively stable long-lasting state that is thought to increase the efficiency of the plants response to pathogens. It appears this "memory" in plants involves epigenetic mechanisms that make it quicker and easier for the plant to activate it's resistance genes in response to pathogen attack ( http://pcp.oxfordjournals.org/content/55/11/1859.full ). It is also interesting that among the whole bunch of genes that plants turn on as a part of this defense response to pathogens are genes for chitinase and glucanase.
 

JAB

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Keep us posted on your experiments. Very few growers take the risk to try different things, so it is refreshing not only to see orchid growers trying things but also sharing their finds openly.
Kudos.

JAB
 

naoki

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Interesting. So are you adding chitin, cellulose etc. at the brewing stage, or are you adding to the vermicompost?

Feeding microbes is interesting. I have "fed" cellulose (basically added corrugated cardboard pieces to the potting mix), and my experiment was not positive. I'll post this at one point. But chitin would be interesting.

I haven't read about ISR yet, but are there negative effects of ISR expressed all the time (when there is no pathogen threat)?
 

myxodex

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Interesting. So are you adding chitin, cellulose etc. at the brewing stage, or are you adding to the vermicompost?

Feeding microbes is interesting. I have "fed" cellulose (basically added corrugated cardboard pieces to the potting mix), and my experiment was not positive. I'll post this at one point. But chitin would be interesting.

I haven't read about ISR yet, but are there negative effects of ISR expressed all the time (when there is no pathogen threat)?
I will add some ground up crab shell flakes to the vermicompost along with some composted horse manure ( a good source of cellulase degrading bacteria ). I'm going to try making VCT brews with colloidal chitin and at least one other polysaccharide, probably cellulose. I might also use a small amount of kelp extract in some brews. Note that almost all of the bacterial polysaccharide degrading enzymes are extracellular and so the sugars released will be available to non-degrading bacteria as well, but it will be a gradual release dependent on the presence of the degraders, so this dependency should help prevent a opportunist (copiotroph) domination of the brew. Copiotroph dominance is more likely with molasses which is 70-80% sugars, all directly available from the outset. My basic practical outline is described below ... any suggestions/modifications will be gratefully recieved and considered. I will only be able to begin in spring/summer when the temperatures warm up, at the moment the worms are rather inactive due to low temperatures. I've ordered most of the materials to prepare the polysaccharides for use and this I can start soon.

Step 1 - making the brew and inital testing
For this I will need to make colloidal chitin because it is too expensive in purified form and vendors of it are scarce. I've made it before a long time ago when I was working on slime moulds (myxomycetes). Essentially you grind up crab shell flakes into as fine a meal as possible and dissolve this in concentrated HCl (36%), then dilute this into a larger volume of water and the chitin precipitates out in a "colloid like" form. This then has to be desalted by washing which is a bit tedious but not difficult (coffee filter works well for this step). The advantage of this stuff is two fold; firstly it has a large surface area and can be degraded by chitinases very efficiently, and secondly you can prepare nutrient agar plates with it as the major carbon source. It gives a milky opacity to the agar, and dilution streaks of the VCT that contain chitinase producing bacteria will give colonies with clear zones or halos around them, so I will be able to estimate the percentage of chitinase producing bacteria in the brew. The amorphous cellulose is prepared in a somewhat similar manner, but for this you dissolve microcrystalline cellulose powder in 85% phosphoric acid, then dilute into water to precipitate and desalt by extensive washing as with the chitin. This is a good source of cellulose for microbes to degrade as you've destroyed it's natural crystallinity which is more difficult for cellulase enzymes to attack. Unfortunately using it in agar plates as an assay, as with the chitin, is tricky because the heat of autoclaving causes it to partly recrystallize meaning that any halos around colonies are harder to spot ... but I have an idea that might at least reduce this problem. Beta-1,3-glucans are more tricky as they are expensive in purified form, and testing for glucanases would require access to a laboratory which I don't have. I might try using something like a shiitake mushroom powder but haven't decided on this one yet. There is also a form of amylase pretreated oat bran powder that is enriched in beta-glucans up to almost 30%, the rest being mostly protein and insoluble fibre. Anyway step one is to get a brew that tests positive for chitinase producers and with a bit of luck I can also test for cellulase positive colonies. Without some positive results with these tests I might not proceed with step 3.

Step 2 - testing on plants
I will use my least favourite paphs for this and some non orchid seedlings (the latter first).
Another way of testing the brew is to see if I can detect auxin activity. It is estimated that approx 70% of known PGPR species make IAA, and the vast majority of these do it from tryptophan as the precursor. So adding tryptophan to a separate portion of the brew for a secondary brewing step, should increase it's root inducing potency. So cuttings of some easily rooted plants, with brew +/- tryptophan ... if the + tryptophan treatment is significantly stronger at promoting rooting then IAA production is likely. Crude, but might just work with a series of appropriate dilutions.

Step 3 - feeding PGPRs in the pot
The idea of feeding the PGPRs in the medium is going to be something I will try cautiously to begin with. However, as Ray pointed out above Inocucor is made using seaweed extract which contains both complex carbohydrates and some amino acids, and so some folk are already feeding their pot bugs when they supplement their feeding with this. The colloidal chitin and amorphous cellulose are fine precipitates which are easily suspended in water and so could be easily provided at low concentrations in an evenly dispersed manner mixed in with the fertiliser solution. The problem is if the pot pH gets too acidic then fungi will take over as the bacteria will become less efficient at repressing them, so pH management could be important for this to succeed. I've already found that including organic acids seems to have been beneficial... I feed at about 20 ppm N with about 10 ppm total organic acids ( malate, succinate, alpha-ketoglutarate and citrate supplied as NH4 and K salts) and amino acids (10 ppm total supplying about 2 ppm of the total N ). So I'm already providing quite a bit of bug-food without any problems, and I probably won't add any more than 10 ppm polysaccharide. Incidentally, I don't use EDTA in my fertiliser because with organic+amino acids there is no need for it.

As for the last point, yes, ISR can cause some stress, and as I understand it, which is not a lot, it is signalled by ethylene and/or jasmonic acid. It is thought by some workers in the field that one of the benefits of PGPR's is that many of them also produce the enzyme ACC deaminase which supposedly stops eccessive ethylene production by preventing re-uptake of root excreted ACC which is a precursor of ethylene production. This is popular, but not a universally accepted idea, but it does seem as though PGPR's can induce ISR and prevent excessive stress or at least that is what I gather. There is a more recent review on ISR and PGPR's than the van Loon review I linked above, but frustratingly it is behind a paywall, so if you are able access this you will most likely get a better answer than I can give ( http://www.annualreviews.org/doi/abs/10.1146/annurev-phyto-082712-102340 ).
 

myxodex

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PS. I have just discovered that the review on ISR and beneficials ( http://www.annualreviews.org/doi/abs/10.1146/annurev-phyto-082712-102340 ) is readable online by clicking the "go to full text" button. Although some interesting stuff it doesn't actually cover the stress aspect, just that the priming mechanism in ISR involves less synthetic cost than SAR. There are a load of publications about PGPR's reducing stress and most of them invoke the ACC deaminase mechanism.
 

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Thank you very much for lots of good info. I started to read these, and it is pretty interesting!

Does chitin works against bacteria, too? Pieterse's review mentioned that it is used as a pattern recognition of fungal existence.

I have been dismissing those products which contain Pseudomonas, Bacillus etc., but they may do something to orchids, too. From the review, I wasn't sure how specific these PGPRs are to the associated plants.
 

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I like to open my flasks for as long as possible before handling the seedlings.
As we know, the agar becomes smothered in mould within 2 days of opening. I think I have mentioned this before but adding a compost tea not only eliminates the mould but keeps it from returning so the seedlings have a good chance to harden off properly before getting blasted with water and shoved into the cruel world. It's made a big difference in the survival rate and the ease of handling for me.
It's important not to let the agar dry out so I add either more solution or plain rain water whenever the film of water starts to dry out.

Paph virens opened 4 days ago and treated



BTW I also add some high alginic acid fermented kelp extract for extra carbon and etc.

Paph vietnamense opened 1 week ago


Paph delenatii opened 3 weeks ago





Here's a flask of Dendrobium carronii which was opened 36 hours ago and had already developed a film of mould. _ just after treatment.....I will pour off the excess solution until the agar is just covered

 

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