237 Bagged Worm Castings - Two Views

Show Transcript

GB 237 TRANSCRIPT Worm Castings, Pumpkin Soup

Farmer Fred  0:00

Garden Basics with Farmer Fred is brought to you by Smart Pots, the original lightweight, long lasting fabric plant container. It's made in the USA. Visit SmartPots.com slash Fred for more information and a special discount, that's SmartPots.com/Fred.

Welcome to the Garden Basics with Farmer Fred podcast. If you're just a beginning gardener or you want good gardening information, you've come to the right spot.

Farmer Fred  0:31

Last Spring (Episode 193), Debbie Flower and I discussed the viability of bagged worm castings. According to one study published in a peer review journal, bagged worm castings start losing their effectiveness after 60 days.

There are those who disagree with that study, calling it invalid. Today, we revisit our chat about bagged worm castings with Debbie Flower, and add in an opposing viewpoint, from longtime organic gardening advisor Steve Zien. We leave you to draw your own conclusions about the viability of bagged worm castings.

Also, as timely as the decorations on your front porch in late October, we have a tasty recipe for Curried Pumpkin Soup. The secret? Adding in other winter squash varieties that you might be growing in your own garden. We’re podcasting from Barking Dog Studios here in the beautiful Abutilon Jungle in Suburban Purgatory. It’s the Garden Basics with Farmer Fred podcast, brought to you today by Smart Pots and Dave Wilson Nursery. Let’s go!

WHAT IS THE LIFESPAN OF A BAG OF WORM CASTINGS?

Farmer Fred  1:37

We like to answer your garden questions here on the Garden Basics podcast. You know how to get in touch with us: you can leave a message at SpeakPipe, speakpipe.com/gardenbasics, you don't incur any phone charges that way. And of course, you can always call us and leave a question: 916-292-8964916-292-8964 . A couple of other ways you can get some questions into us. If you go to gardenbasics.net, you can leave a question there. Maybe you have pictures you want to send along, that's always helpful. Send your question and your pictures to me via email to Fred at farmerfred.com. And again, speakpipe.com/gardenbasics. That's a great way to get your voice on the air here, or go to gardenbasics.net, and leave a question there. Debbie Flower is here to help us answer the questions, and people love to get information from Debbie. You know, by the way, it's trademarked now, she is America's favorite retired college horticultural professor.

Debbie Flower  2:42

Gee, Thanks, Fred.

Farmer Fred  2:46

And Aileen left us a message at speakpipe.com. And Debbie, it was a very intriguing message.

Debbie Flower  2:53

It was. This is a good thought. She's a good thinking woman.

Farmer Fred  2:56

All right, here's Eileen.

Aileen  2:57

Hi, Farmer Fred. I have a question about worm castings. I've heard that worm castings are really kind of volatile, and they only stay good for like 15 minutes after you harvest them out of your worm bin. But then I also see them being sold in bags at garden stores. So what's the truth? I mean, it's probably not the worst thing to add old worm castings to your garden. But maybe it doesn't even hold a candle to what your backyard worm castings can do? Help me out here. Thank you.

Farmer Fred  3:26

Well, Eileen, you're right on several points there.

Debbie Flower  3:30

Yes, she is. Yeah.

Farmer Fred  3:32

But there's one that we will be emphasizing too, is that old worm castings may actually repel water.

Debbie Flower  3:39

Right. Old worm castings don't have as much value as the new ones right out of the garden. As she mentioned, there was a study actually  published in 2014, in the Journal of Applied Horticulture. It's called, "The Effect of Storage on Some Physical and Chemical Characteristics of Vermicast." So Vermicast, being the worm castings.

Farmer Fred  4:02

Being America's Favorite Retired College Horticultural Professor, you're probably familiar with the Journal of Applied Horticulture. Would you say that is a reputable publication?

Debbie Flower  4:13

Yes, it's a peer reviewed publication, which means they get the article and they will send it out to peers, people who are similar to the people sending it in. So in general, these are professors or graduate students who are doing this study and people will review it for different things. This statistician will review the article for making sure that the statistics were done correctly. In this case, probably a worm farmer or worm researcher will read the article to make sure that the things said about worms and worm castings are legit. So it goes out to a number of people in the field, who then make comments and it has to pass this peer review before it will be published in the journal.

Farmer Fred  4:53

To give you a short answer, Aileen, those bagged worm castings, according to this study, they're good for 60 days.

Debbie Flower  5:00

Right. It talks about what's in them. Fresh worm castings have a lot of nitrogen in them and a lot of nitrogen can be very good in the garden or there can be too much and it can be too hot and burn the plants. So you get a lot of nitrogen. You get some iron, some zinc, some copper, phosphorus, potassium. Worm castings do contain organic matter and they contain very broken down organic matter which we call humus, which is pretty stable. It has some good characteristics in the soil and one of those being that it is high in what we call "cation exchange capacity". It holds on to cations, or positively charged ions. So nutrients that plants can use, as well as holding on to water and it lets them go when the plant needs it. All of that is good and that humus part of it will not change over time. But there are also live organisms in fresh worm castings, and those don't survive forever. And they're good live organisms, and there's water too. And there's water. Yes, it's moist, and that disappears and that disappears, right.

Farmer Fred  6:01

Let me read the abstract from this study in the Journal of Applied Horticulture to give you an idea in fairly simple English, so here we go: "The study revealed that most of the characteristics of the castings were retained during the first 60 days of storage. Further as storage was continued, the physical properties such as total and water filled pore space were reduced by 11 and 40%, respectively. The water holding capacity of castings also reduced about 82% and exhibited high degree of water repellency. Whereas, the bulk density and particle density of castings increased two-fold. These changes may impede the water availability, oxygen diffusion and plant root penetration in the field. The nitrogen loss of 49% was recorded due to intense ammonia volatilization. There was more than 75% loss in potassium and phosphorus content and a significant reduction in the concentration of minor and trace nutrients. These changes in the properties of castings reduced the beneficial impact of vermicast on plant growth."  Well, that's pretty direct.

Debbie Flower  7:14

It is, it is. And there are tables in this article of their results, the amount of time they looked at these worm castings were seven days every week, seven days, 14-21 days, then the table skips to 60 days, then 90 days and then greater than 120. So it's not all that long. 120 is four months.

Farmer Fred  7:33

That's right. And what concerns me is the fact that if it gets too dry, it's going to repel water. And it's going to make it tough as that abstract mentioned, for plant roots to penetrate it.

Debbie Flower  7:45

Right. So you know, you're not going to want to grow in 100% worm castings.

Farmer Fred  7:49

Yeah. And if you do use it, you're probably want to somehow saturate it again, too, especially if it's older than 60 days.

Debbie Flower  7:57

Yes. So that would be putting it in a bucket, let's say, and mixing it with some warm water, and using your hands.

Farmer Fred  8:04

Well, that brings up an interesting thought. We just did a segment about compost tea. And I'm wondering if you took those worm castings and put them in a permeable bag, into a five gallon bucket, along with water and an aquarium pump, and basically put air back into the system, and then used it, if that would help.

Debbie Flower  8:23

Good question. Yeah, we don't know the answer. We'd have to do the research. And again, you're looking at after 60 days, after 60 days after harvest, or 60 days of storage.

Farmer Fred  8:34

I have talked to the makers of worm composting products, I have talked to retail outlets that carry them to get their point of view on this. The manufacturer says, "We can't make it fast enough, and get it out there fast enough, there's such high demand for it." And that's a good thing. Because that means that when a pallet of worm castings shows up at your favorite garden center, it's going to move quickly. And then you, the consumer, has to be the one to use it within a month or so.  But generally speaking from the plant where it's made, to the retailer, may be just a few days, hopefully. And depending on how many pallets of worm castings that garden center purchased, it may disappear within a week, it might take a month. And if it takes longer than two months, I think as a customer, what I would get in the habit of doing, if you buy worm castings in bags is to ask them, "when did this arrive?" And if it's longer than 60 days, if they're telling the truth, maybe do something else.

Debbie Flower  9:37

Yeah, there are people who do it as their local small business, right?

Farmer Fred  9:42

Yeah, that's a good point.

Debbie Flower  9:43

So, that's something to look into. You can get it .That's something I asked for  Mother's Day one year and my husband found a local vermicomposter and she had another job and so she only harvested on certain days and he had to wait for those days and then drive over to her house and and buy bags of vermicompost. That was very fresh.

Farmer Fred  10:05

I knew a guy in Galt (CA) who said, "yeah, come on by. And if you shovel it, I'll give you 20% off." There you go. So yeah, it can be that fresh, it can be that fresh and to apply it that fresh would be great.

Debbie Flower  10:17

It would be cool because there are microbes, live organisms in the worm castings that are beneficial to the plants, and you would retain most of those by applying it fresh.

Farmer Fred  10:27

So Aileen, I guess you're gonna have to form a close alliance with your favorite garden center or nursery. And hopefully, they will level with you about how long that packaged product has been there.

Debbie Flower  10:40

Hopefully, they will know.

Farmer Fred  10:41

Hopefully. Yeah, and that's the other thing too. I went around checking bags for dates. And I didn't see any dates. I saw bar codes. So maybe there are manufacturing dates embedded in the barcode? But how do you get access to that?

Debbie Flower  10:54

And then where is the plant that it was made? Is it on the East Coast? And so this sat in a truck for a week? I don't know.

Farmer Fred  11:02

Yeah, there are worm casting factories, if you will, here in California, several of them. But I imagine every area would have their own local business, it seems to be a very localized industry. The bag soil amendment industry, it seems to be a very local enterprise.

Debbie Flower  11:18

I agree. And worm castings are often associated with dairy farms, because the manure is fed to the worms and the worms turn it into vermicompost. I read another paper, another article where the thing that the worms were fed was paper. And so it might be a recycling thing. I don't know exactly where this compost is being made, or what they're being fed, or the effect that that would have on the result.

Farmer Fred  11:43

We'll have a link in today's show notes on this report from the Journal of Applied Horticulture on the effect of storage on some physical and chemical characteristics of vermicast, you can read it for yourself. (https://www.horticultureresearch.net/jah/2014_16_2_112_116.PDF ).  At the very end, there are references that you can research for yourself on worm castings, and everything that was in this report.

Debbie Flower  12:03

Yeah, quite a number of them. It was very well researched. Yeah. Another tact to take is we're not there right now at this time of year; but in your own compost pile, or as you do on your vegetable beds, if you put them to sleep in the fall usually put leaves on them and cultivate your own population of worms that will leave the worm castings right where you want them.

Farmer Fred  12:26

Yeah, it's amazing how that works. I'm always amazed at when you start mulching soil with a good organic product like oak leaves or chipped and shredded tree parts. And a year later, you go and dig down. All of a sudden, all these worms are there that weren't there before.

Debbie Flower  12:43

Yes, worms are incredible. I am not super well versed in in vermicomposting. I have done it a few times. And I've watched the demonstrations at the Fair Oaks Horticulture Center. But their population ebbs and flows, depending on the food supply.

Farmer Fred  12:58

Right, that makes sense. That's true of many things that live in the soil do. And it's one thing we learned about with compost tea: You're wasting your money if you're applying compost tea to soil that doesn't have an active microbial life in it already, if it’s dead. Yes, it needs some life, first, in order to get it to multiply. But as far as making your own worm castings, if you have a worm bin, well, that's a good place to start. But if you have any working knowledge of it, you know that it takes months to get maybe a couple of cups of worm castings.

Debbie Flower  13:34

Yeah,  the part I liked the best was the leachate, the liquid, that came out of it. And I would collect that. My worm bin was a tiered commercially made product, a tiered one. And they had a spigot for the liquid to come out the bottom. And I would dilute that and water my house plants with it and they loved that stuff.

Farmer Fred  13:40

And that's from your personal experience.

Debbie Flower  13:45

That's my personal experience.

Farmer Fred  13:57

It's not a peer reviewed study, because there are no peer reviewed studies on worm leachate. And it's a mystery, until somebody studies it,  how to apply it and where to apply it. But just in hearing people who have worm castings, they will have worn leachate and what they do with it, and the results that they see. And yeah, worm leachate is easy to get.  I'm up a gallon every week.

Debbie Flower

Are you diluting it?

Farmer Fred

No, I'm not.

Debbie Flower

That was my fear. When I got it I feared that it would be too hot, as I was talking about at the beginning, about to have too much nitrogen in it or too many salts, which are how plants can absorb nutrients. And when it's the right amount, it's great. But if it's too much, then it burns. The plants can burn the roots. So I was diluting it.

Farmer Fred  14:56

I would think it would really depend on what you were feeding the worms.

Debbie Flower

Yeah, that’s true.

Farmer Fred

Garbage in garbage out. That's true. I remember Jack LaLanne, any of you remember Jack LaLane, TV exercise freak?

Debbie Flower  14:48

Yes.

Farmer Fred 14:48

And he had a white German Shepherd. But he always used to say that the best fed person in your household is the garbage disposal. Because all that great stuff that people take out of vegetables before they boil it, this is back in the 50s and 60s, went down the drain. And that was the healthiest part of the food. So if your worms are eating healthy fruits and vegetables that you're discarding, you're going to have a very healthy bunch of worm castings.

Debbie Flower

Right. I wonder about that other article I read where the worms are eating paper. Paper is very high in carbon, it has a little bit of nitrogen, but very high in carbon. And so what are they going to get out of that? And I don't have the answer.

Farmer Fred  15:53

Yeah, I don't know that either. There's a lot more to learn about this.

Debbie Flower  15:57

This was a 2014 article, I haven't found much since. I wish people would do more research on it. If you're into this, go get your PhD, do some research.

Farmer Fred  16:11

And if you're an industry, you can write a grant for it. If you're in the manufacturing business of soil amendments, I would if I owned one of those companies, I'd pay for those studies. But then you'd be accused of biased results.

Debbie Flower  16:25

Unfortunately, many of the studies done in horticulture and I assume other sciences as well, are funded by industry because it takes money, it takes money to pay the student and the professors who work on it, and they need supplies and time and it has to come from somewhere.

Farmer Fred  16:45

Yes.

Debbie Flower  16:49

This article, there were some that I was reading were that weren't quite as applicable, but they were so into a certain product with a product name they used in the article and that just turned me off. I didn't want to know about that product. I wanted to know about the worm castings in general, right?

Farmer Fred  17:05

Well, Aileen, there you go. If you have the room to have a big worm farm, that would be the best way to get lots of worm castings quickly. It really comes back to what we've always talked about: gardening is GIY, grow it yourself. That's the healthiest food you can get. And in this case, the healthiest soil amendment. So I hope that helps Aileen. If you want, go to the show notes and download the link to "Effective Storage on Some Physical and Chemical Characteristics of Vermicast". Debbie Flower, thanks for your help on this.

Debbie Flower  17:37

It's a pleasure. You're welcome, Fred.

Farmer Fred  17:40

As we pointed out at the beginning of this episode, not everyone agrees with that study about the viability of bagged worm castings. Coming up: We talk to someone who says that study needs a lot more work. It’s Sacramento's organic advocate, Steve Zien. We will hear from him and his views on bagged worm castings, when we come back to the Garden Basics podcast.

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BAGGED WORM CASTINGS: A DIFFERENT VIEW

Farmer Fred  20:00

You heard Debbie and I discussing that study about the effect of storage on some physical and chemical characteristics of Vermicast, there was a study done in India at the Center for Pollution Control and Environmental Engineering, and it was printed in a reputable journal, The Journal of Applied Horticulture, back in January of 2014. Let me read the abstract from that report for you. That study was a peer reviewed study, by the way. Let me give you some of the basics here.

“It's widely acknowledged that vermicast has beneficial effects on plant growth, but little is known on how the manner and duration of storage affect the vermicast’s quality. In an attempt to cover this knowledge gap, we have carried out a study on changes in physical and chemical properties of vermicast as a function of aging when it's stored. The study revealed that most of the characteristics of the castings were retained during the first 60 days of storage. Further, as storage was continued, the physical properties such as Total and Water filled pore space were reduced by 11 and 40%, respectively. The water holding capacity of castings also reduced about 82% and exhibited high degrees of water repellency, whereas the bulk density and particle density of castings increased two fold, and these changes, though may impede the water availability, the oxygen diffusion and plant root penetration in the field,  nitrogen loss of 49% was recorded. Due to intense ammonia volatilization, there was more than 75% loss in potassium and phosphorus content and a significant reduction in the concentration of minor  and trace nutrients. These changes in the properties of castings reduced the beneficial impact of vermicast on plant growth.”

Some people have taken issue with that study. One of those persons is Sacramento organic advocate, Steve Zien. And Steve, I know I raised your dander after you heard that on the podcast about worm castings and their limited life. I would like your thoughts about that.

Steve Zien  22:01

Their study about the bulk density in the water holding capacity and water repellency, and nutrient loss, is probably all aboveboard.  But they utilize that information, and in my opinion, incorrectly, concluding that these changes, and this is a quote, these changes in the properties of castings reduce the beneficial impact of vermicast on plant growth. And, you know, there are numerous problems with the study. Firstly, they assumed without any study that the issues that they found with aged bagged worm castings, when it's applied to the soil, will affect the soil in the same way, they did not do any research. And therefore, their conclusions, in my opinion are invalid, you take worm castings that are dried, and they've lost some of their nutrients. And primarily if they've lost their bulk density and water holding capacity and repel water, all of that can be changed and reverted back to close to the original conditions by simply adding more water. Years ago, when I managed a local nursery, peat moss was very, very popular. And when we sold the bagged peat moss, we told people, if you just use this as is, it's really dry, it's going to repel the water, it's not going to absorb water, what you have to do is poke a little hole in the bag. And you have to take a hose and fill up the bag with water so the peat moss will absorb water. If you were to do that with the worm castings, bulk density would increase back to, I suspect, that the bulk density would increase back to normal. Certainly the water holding capacity would get close to being normal. The amount of water content that material holds would increase close to back to normal. It would not repel water anymore. So when it's actually used in the soil, it's not going to have those kinds of influences and they didn't study what this material is going to do when it's added to the soil. So in my opinion, that invalidates the whole thing. They also only fed the worms neem leaves . And neem leaves do not create a healthy vermicompost. You need to feed your worms a variety of different things to get good quality material. Also, neem is an insecticide. And there are some questions and to my knowledge it has not been studied very well, if at all. What a diet of 100% neem will have on your composting worms, Because it's an insecticide, there is certainly  a possibility that it could become toxic. It certainly isn't a healthy, well balanced diet. They also, in this study, did not talk about how they stored bags of compost, was it in a bin where it got really, really hot in the summertime? Was it in a shaded storage building where it stayed cool. The study talked about a significant loss of nutrients. It talked about 49% loss in nitrogen 75% loss of phosphorus. And they really misrepresented the significance of this. Even though it's a large percentage of nitrogen and phosphorus and potassium that is lost, the actual amount is so small to be barely barely significant. Typical nitrogen, phosphorus and potash ratio, those three numbers that you find on the bag for worm castings, is 1-0-0. So if you lose half of your nitrogen, you're losing half of 1%. How significant is that? If you're losing 75% of your phosphorus, and you have pretty much 0%, phosphorus, and 0%, potassium, and you lose 75% of that, 75% of nothing is nothing, it's not significant, it really doesn't mean anything. As far as the water repellency is concerned, like I mentioned earlier, you just leave it in the bag, fill it up with water, and you're going to restore most of the physical characteristics. They also did not evaluate the biology in those bags, and whether the storage is going to affect them. My guess is that the the majority of  the biology would survive. They go in a dormant state. Debbie talked about that in the previous show that discussed this issue, they would survive. And then once that material is really moistened, and the physical properties are restored, the biology would probably start producing more of the nutrients. Again, common problem with  university research and a lot of the scientific research is that they don't really understand much about soil health and how the soil actually functions with the biology. And the fact that it's the biology that makes the soil function. It's not just nitrogen, phosphorus and potash. Because they didn't evaluate the biology. This study was only done in the lab, it wasn't done in the field. We really don't know the effect of that material, when it is actually used, whether having it stored is really going to be a problem.

Farmer Fred  27:34

I agree that using just neem leaves was probably not a good idea that you do want a variety of products if you are raising worms for vermicasting, green waste is preferable if you're growing vegetables, for example. So anyway, in this study, which was conducted at Pondicherry University in India, neem leaves were collected from the campus. Quoting from the study:

“The collected leaves were washed with water to remove adhering material and soaked for 48 hr in order to remove phenolic compounds and to make substrate softer and palatable to earthworms (Nath et al., 1987; Agarwal et al., 1991). Rectangular wooden boxes (depth 30cm, width 35cm, length 39cm) were used as vermireactors. The reactors were filled from bottom up with successive layer of coarse sand and soil to a thickness of 3 and 5cm, respectively. Neem leaves was added as feed with the earthworm species Eudrilus eugeniae, an epigeic worm. After 2 weeks, the vermicast was harvested. An aliquot of fresh castings was analyzed immediately whilst the rest were stored for <7, 14, 21, 60, 90 and >120 days. The casts were stored in the polyethylene bags of 20 micron thick and 7 x 10 inch size. Plastic bags filled with 500 g of vermicast were stored at room temperature in order to imitate the general way of storage of vermicompost in commercial sectors.”

Well, that's fine and as far as indoor storage, when you're manufacturing it. But once it leaves the manufacturing facility and goes to a retailer, I think these researchers gave retailers a break because some of them do store these bagged products outside where the rate of decline may be a lot quicker. In fact, I was looking at worm casting bag labels looking for any sort of advice as far as how to store them, or any precautions. And I checked. I went on Amazon, put in “worm castings” and up popped about 20 different products. And I checked the labels of 12 of those 20 products. And only one of them had any warnings whatsoever. And it talked about this: This was on a bag of Eden's Best organic earthworm castings. And at the bottom, it says, Do not ingest or inhale, keep bag closed and store in a cool dry place. Well thank you for that. But there's no manufacturing date on So if it's one thing that I wish manufacturers would do is to put either a use by date or a manufacturing date, clearly on the bag, don't say go to the website for more information. No, but I want to see it on the bag. I want to know how old the product is. Anytime I’m buying.

Steve Zien  30:16

I fully agree, I think, especially with organic products that are meant to contain and add beneficial soil biology, I think there is a life span for the critters. And so it's helpful to know that the older the material is, likely the less biology is going to be there. And so it's nice to know. We also need to do research on how long the