Sprucing Up Your Springtime Soils

29:39 minutes

Credit: Shutterstock

For many gardeners, spring is the time to tend that garden they might have been neglecting all winter. One of the first steps is getting the soil back into shape. David Lindbo, the director of the Soil Science Division at the U.S. Department of Agriculture, says soil is “an entire ecosystem unto itself.” He discusses how different types of soils are formed and shares methods for examining soil’s texture and color, which can clue you into its water and mineral content.

[Is healthy soil the low-tech solution to climate change?]

And master composter Rebecca Louie explains how to turn table scraps into compost using methods such as under-the-counter worm bins, backyard digesters, or bokashi fermentation.

European Nightcrawler, which is bigger and slower to breed than the Red Wiggler. Found in a garage worm bin. Credit: Rebecca Louie
Corn cob sprouting in a worm bin. Credit: Rebecca Louie

We asked SciFri listeners to share their compost bins and techniques.

Do you compost? Tell us more in the comments!

Segment Guests

David Lindbo

David Lindbo is director of the Soil Science Division at the U.S. Department of Agriculture’s Natural Resources Conservation Service in Washington, D.C.

Rebecca Louie

Rebecca Louie is the founder of The Compostess blog. She’s author of Compost City: Practical Composting Know-How for Small-Space Living (Roost Books, 2015). She’s based in New York, New York.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Spring. It’s the time to stroll through your garden and enjoy the blooming flowers and sprouting fruits and the veggies, but like many growers, like me, you may have let your garden go– let it go during these cold winter months.

Now the first step is bringing your soils back. You know that as a gardener, and my next guest says soil is an ecosystem unto itself. He’s here to fill us in on some soil science and tell us how we can read the profile of our clays and silts just by looking at them. David Lindbo is the director of the Soil Science Division at the US Department of Agriculture’s Natural Resources Conservation Service. Welcome to Science Friday.

DAVID LINDBO: Thank you for having me.

IRA FLATOW: Let’s talk about the difference– I know this is going to sound weird because everybody wants to know– between dirt and soil. People sort of mix the two up, don’t they?

DAVID LINDBO: They do. We all say dirt is the stuff that’s under your fingernails. Dirt’s the stuff you sweep off the floor. Soil, on the other hand, is way more than that. It’s one of the four things you can’t live without, water, air, sunlight, and soil. All of our food comes from soil. All of our clothing comes from soil. All of our houses, our structures, so without soil, you would be hungry, homeless, and naked.

IRA FLATOW: No, and I now understand that each state has a state soil. I really didn’t realize there were so many classes of soil. How does that soil form differently, and why are there are so many different types?

DAVID LINDBO: Well, soil represents where it formed. It forms based on its climate, how long it’s been there, the organisms that live in it and interact with it, the relief where it is on the landscape, and the parent material. So just like we have parents, soils have parents, too. So it’s a mixture of all those five things that help soil or make soil the way it is.

IRA FLATOW: All right. I’m out– I’m going out in my garden now. It’s springtime. I want to assess the state of my soil. Now what should I do?

DAVID LINDBO: OK, several things. One is just take a handful of it. Smell it. It should spell earthy, kind of sweet, not sour. So smell really does tell you a lot about the soil.

It should crumble easily. If you dig it and it comes out as a block, it’s maybe compacted. You can also determine if it’s compacted by just sticking a flag or a coat hanger into it, and if it resists, you have some compaction.

Feel what it’s like. Is it really sandy? May have some– may need to add more organic matter. If it has too much clay and it’s too sticky, again, organic matter can help a great deal. If it feels smooth and makes a nice ribbon about, say, an inch to two inches long, that’s a loam, and that’s a great place to be for your garden.

Also, look at the color. If it’s not real dark, you probably don’t have a lot of organic matter. And organic matter can really help your garden. The more you can add, the better off you are.

IRA FLATOW: And we’ve had a lot of rain here, and the soil– it can still be very wet. Should we wait for it to dry out a bit before–

DAVID LINDBO: Yeah, a little. You don’t want to work the soil when it is too wet. That can destroy the structure, and the structure is how the individual particles of sand, silt, and clay are arranged. If you break the structure up, you can smear the soil, puddle the soil, and that can actually cause problems and increase the amount of compaction that you have in the soil. So don’t work it when it’s too wet.

IRA FLATOW: Don’t work it. And if you have very compact, compressed soils, should you dig it up? Should you till it, or aerate it?

DAVID LINDBO: Aerating it a little bit is fine, but you don’t want to work the soil too much. It’s kind of counter-intuitive. Tilling the soil and trying to break it up mechanically can actually cause more damage to it. What you want to do is add organic matter. Just gently work that in. The microbes and the organisms that live in the soil will start to create aggregates, which is exactly what you want in the soil.

IRA FLATOW: So if you till it too much, you’re basically breaking up the microbiome that’s in the soil.

DAVID LINDBO: In some ways. It’s kind of like if you have a bowl of granola, you can add some milk to it, and it stays, you know, pretty crunchy. But if you took that granola and crushed it before you added the milk, and then added the milk, you end up with mush. And you don’t want that in the soil.

You want the soil to have good strong aggregates. It allows the roots to penetrate. It allows water to drain. And you don’t want your roots to be waterlogged. You want a nice mixture of air and water present.

IRA FLATOW: All right, now we’ve got our basics down. We’ve gone to the shops to buy our plants. Now we’re digging our hole. It sounds kind of pretty basic. Lots of people, they dig a hole, they may pat and compact the walls of the hole, make it a little bit more stable. Is there a right way and a wrong way to dig a hole and fill it in?

DAVID LINDBO: Well, the way you just described it is the absolute wrong way to do it. Think of the–

IRA FLATOW: Explains my gardening a little.

DAVID LINDBO: Yeah. [LAUGHTER] So what you want to do is dig a hole. And we say if you have a $5 plant, you want a $20 hole. Time that you spend preparing it will be beneficial. Go in, dig the hole out, make sure that the edges of the hole are broken up, they’re not smeared. That allows the roots to be able to get into the hole, allows water to get out of the soil as well as back in, and your plant will be much happier.

Also, adding some compost to the bottom of the hole to make sure that you don’t put the plate in too deep, so that it’s in there good. And then at the end, you don’t have to pat down around it. A little bit of a ridge around the edge of the hole to trap some water would be great, but don’t pat it down. You’ve just kind of destroyed what you’ve just done.

IRA FLATOW: See, because I always had heard you should pat down the plant so that the roots take– make good contact with the soil.

DAVID LINDBO: You do need to make sure that there’s contact at– you know, by watering it afterwards, that allows the structure, it allows the soil to settle a little bit, and that’ll give you the good structure. So be gentle.

IRA FLATOW: Now let’s go to Esther in Charlottesville, Virginia. Hi, Esther.


IRA FLATOW: Hi there.

ESTHER: My question was, I have a lot of red clay in my yard, so it’s really hard to get anything to grow just because there isn’t a lot of nutrients and it’s super, super packed down. What would you suggest to do in a situation like that?

DAVID LINDBO: Adding organic matter, compost. Work it in. Again, don’t overtill, but just work it in with a tilling fork would be the best thing that you can do.

And you need to do this over time. One application is not going to be enough for you. This is a constant process to rebuild the microbes in the soil. The organic matter will benefit you for years to come. This is how we can make the soil healthier.

IRA FLATOW: Thanks for calling, and we have a follow-up to that. We have a tweet from Happy Bees Two who says, “The clay soil in my garden stains my hands, leaves a dry residue that stays through multiple soap washes. What’s up with that?”

DAVID LINDBO: That’s just iron oxides. A lot of times, the red soil, the red color that you see is coatings on the particles. And that is simply iron oxide coatings. It’s kind of like paint. And yes, it will stain your fingers.

IRA FLATOW: And a tweet from Cindy [INAUDIBLE] says, “I’ve left potting soil in a bucket pretty much enclosed in a garbage bag on my south-facing balcony. Have I killed helpful organisms?”

DAVID LINDBO: You may have changed them a little bit, but no, you haven’t killed them. As soon as you put that back out in the garden, there are millions, billions of microbes that will just keep growing. It’s organic, so they’ll be eating whatever’s in that potting soil.

IRA FLATOW: Do you do you have a favorite soil type? One that’s really interesting to you?

DAVID LINDBO: My research when I worked on my doctorate was on fragipans, and that’s– so that’s still the soils that I like to see. They’re difficult to understand, very difficult to dig, but I’ve always enjoyed working with them.

IRA FLATOW: Well, what is that? Like, explain that. What is that?

DAVID LINDBO: So a fragipan is a horizon in the soil that appears to be cemented, but it really isn’t. When it gets wet, it’s– you can dig through it. As it dries out a little bit, it gets very brittle, prevents water from moving through, and it also prevents roots from moving through. So not good if you’re gardening. But it’s interesting to look at how it’s formed, why it’s present, and then how to manage it.

IRA FLATOW: Let’s say you have– I mentioned the wet soil before. Let’s say you have very dry soil. Can you just water it back to health?

DAVID LINDBO: No. Not necessarily. If it’s a dry soil or a soil that is very droughty, that drains quickly, like sand, just by watering it really won’t change it. Again, adding organic matter. Sounds– maybe I sound like a broken record, but organic matter does an awful lot to really help improve the soil and improve the soil health. So that’s the best thing you can do to it is add organic matter.

IRA FLATOW: You hear a lot about peats and loams and silty soils. What are those? What’s the difference between them?

DAVID LINDBO: Well, when you say peat, we’re referring to organic matter. And a specific– for a soil scientist, a peat is a very specific type of organic matter in terms of how decomposed it is. We have peats, mucky peats, and mucks.

Peat is the least decomposed. You can still look at it and see that it was plant material. A muck, on the other hand, you can’t tell really what it was. It looks like muck.

When you say loam, that is one of the 12 textures that USDA uses to describe soils. And a texture is simply the percent sand, silt, and clay, and actually has nothing to do with the organic matter that’s present. So texture is– again, no organic matter. Adding organic matter will, again, help the soil.

IRA FLATOW: I see. That’s sort of like a mantra, isn’t it? More–


IRA FLATOW: Can you have too much organic matter?

DAVID LINDBO: You can in– as far as if it’s a truly organic soil, there are certain properties that will be a little difficult to manage. As far as stability, very organic soils are not as strong, so trying to work them or walk across them, you can sink into them. Equipment has some problems with it. But organic soils, when properly managed, can indeed be some of the most fertile soils that we have.

IRA FLATOW: You don’t want to plant into all compost, do you? Just stick stuff into–

DAVID LINDBO: You can, but I– the stability that you get from the mineral material, some of the nutrients that are still there, are beneficial.

IRA FLATOW: Well, thank you very much, David. You’ve given us a little running start. Getting our hands dirty this spring. We love it. Thank you very much.

DAVID LINDBO: Good luck with your garden.

IRA FLATOW: Thank you. I need it. David Lindbo is director of the Soil Science Division of the US Department of Agriculture’s Natural Resources Conservation Service. We’re going to take a break and when we come back, we’re going to stay on the theme of gardening.

Rebecca Louie is founder of the blog Compostess and author of Compost City– Practical Composting Know-How for Small-Space Living. You don’t have a big backyard, you want to work inside your small apartment, we’ll tell you how to create your own soil with composting, including bin worms. Yeah, it’s popular stuff. Well, stay with us. We’ll be right back after this break.

This is Science Friday. I’m Ira Flatow. Around New York City, little brown compost bins have started to appear in different neighborhoods, which has made composting nerds around the city very happy. And I can see my next guest is already giving me a high five on that.

But there are many ways for do-it-yourself composting, and you don’t even need a backyard to do it. We even had a Science Friday office compost bin way back in the day. But for you pro-composters, or if you’re just starting out, you might have some questions. Is your bin too hot? What is worm tea good for? And what can you compost in a studio apartment?

My next guest is here to break down the how-tos of composting. Rebecca Louie is a master composter. She’s also founder of the blog Compostess and author of Compost City– Practical Composting Know-How for Small-Space Living. She’s based out here in New York, and she’s in our CUNY studios. Welcome.

REBECCA LOUIE: Thank you. I’m so glad to be here.

IRA FLATOW: And if– for everybody who has a composting question, you can give us a call. 844-724-8255. You can also Tweet us at SciFri. How long have you been at this, composting?

REBECCA LOUIE: It’s been a fun-filled decade, I think, about now. Yeah.

IRA FLATOW: And let’s talk about this. How easy is it for someone in an apartment to do this?

REBECCA LOUIE: So I think the perception is that composting has to be this Little House On The Prairie sweaty thing that takes place outdoors, et cetera. But actually, there are several systems that can be adapted to small spaces and indoor spaces, so if you don’t have a yard, even if you don’t have a windowbox, you can do it.

IRA FLATOW: All right, let’s get right to the ABCs of this. What do we need? How do we start?

REBECCA LOUIE: OK, well, first, you need to start with a basic understanding of what you’re doing, right? So there’s a balance that happens in any compost system. Your dry stuff and your wet stuff. Dry is like leaves, paper, et cetera, cardboard. Your wet stuff is your food scraps.

Every system has its own special balance. So in an apartment, you could have a worm bin. We’ve got some worms here with us today. Yeah, cute little guys.

Worm bins live in an enclosed space like a storage tote, a bucket, there are commercial systems you could buy as well. The brown, dry stuff, the carbon layers, the bedding that they live in– you fill up the bedding, you dampen it, and you marry it with your food scraps. The worms go in. They eat slowly. They turn it all to black gold.

IRA FLATOW: Is this like a an egg carton, a shredded egg carton it looks like.

REBECCA LOUIE: Yep, egg cartons. There’s maybe some paper towel rolls in there, shredded paper, newspaper. As long as you’re not doing waxy items like a cereal box or a magazine, you’re in good shape.

IRA FLATOW: And you can buy the worms online, or where?

REBECCA LOUIE: Yep, you buy the worms online. You can actually buy them in New York City at the Union Square Greenmarket from the Lower East Side Ecology Center, but it’s a specific species. Some people ask, can I go dig out the worms or pick them off the sidewalk after a rain? Probably not. These are red wigglers. They’re perfect for enclosed spaces. They eat a ton. They reproduce like mad. And they don’t want go anywhere. So they love living in that bin.

IRA FLATOW: And they don’t smell at all.

REBECCA LOUIE: Yeah, what does it smell like in there?

IRA FLATOW: It smells like earth.


IRA FLATOW: Yes, I like that. The good earth. It is a great smell. All right, let’s talk about if you have the room in your backyard, and you want to do some composting, how do we do that?

REBECCA LOUIE: Sure, well especially in a city scenario, you have to think, OK, I’ve got neighbors. Maybe we have to be careful about how we do this. So discretion is often important, right?

Something that I love is the digester, which is some sort of container with holes drilled in the bottom half that’s buried underground. You bury most of it. The lid is on top that you can close and open as needed. And essentially, those holes, end up being passageways for microbes and earthworms, et cetera, to come and eat your food scraps.

IRA FLATOW: And what do you put in there? Is there a rule for what to put in and what not to put in?

REBECCA LOUIE: So digesters are super forgiving. You can put a lot of green material, which is that sort of wet, food scrappy things, but a big consideration is, of course, meat, dairy, cooked food, all those gnarly things. When they’re breaking down your garbage, you know it’s a bad scene, so if it’s outside in the yard, call all the rats. I will say there’s a really exciting solution, which is the fermentation of food waste, which can happen for any type of food waste, your old wine, your old leftovers, whatever. You dump it in, you ferment it in an anaerobic bin with special microbes, and then you can bury it anywhere in soil.

IRA FLATOW: [INAUDIBLE] so it has to be– I know like when I ferment my pickles, it has to be underwater, out of the air, basically.

REBECCA LOUIE: Right, so it’s in a bucket, an airtight bucket. Yep.

IRA FLATOW: Well, let’s get– we have people who need advice. Let’s go to Lisa in Severna Park, Maryland. Hi, Lisa, welcome to Science Friday.

LISA: Hi, can you hear me?

IRA FLATOW: Yes, I can hear you. Go ahead.

LISA: Hi. Great. I just want to say I love Science Friday, and this topic is right up my alley. I’ve wanted to do composting for a long time, and finally, for Earth Day this year, I went to our county, and they gave me this big, plastic thing that becomes a compost bin. And my question has to do with where to put it, because we have a very small yard, which is mostly shaded by my neighbor’s trees, and the instructions said put it in a sunny location. So I haven’t put it up yet because I’m sort of not sure what to do with it.

REBECCA LOUIE: So the exciting thing is you do not have to stress out, really, about where you put it. The reason they recommend it’s in a sunny location is because heat often accelerates bacterial activity and break things down faster. So if you’re in some sort of like epic rush to get the compost now, maybe find a patch of sun.

But what’s really great about composting, is that it’s a flexible lifestyle. So you can stick it anywhere it’s convenient. If there’s a bottom on there, you have a little bit more– you have more choices, because you could put it on a patio. You could put it on concrete. But if it has an open bottom and can drain directly into the soil below it, put it anywhere. Don’t be super concerned about the sun.

IRA FLATOW: Good luck to you. So you can make it out of any crate you have in the backyard?

REBECCA LOUIE: Yeah, one of my favorite things to do is a bucket composting boot camp, which is which is essentially taking a five-gallon bucket, which you can get for free or you can get for a few bucks at the local hardware store. And essentially, if you have a drill and you have determination, you can do it really easily. They can all be adapted, because all they are are closed containers with holes for air and moisture to leach out of, right?

IRA FLATOW: And you have to turn it over, or–? During the–

REBECCA LOUIE: You can. So you know, I have a very big lifestyle. See what fits for you. You can, by turning things, you’re mixing air, you’re mixing microbes, you’re mixing moisture, and you’re facilitating the process. But if you’re lazy– or, I’m sorry, if you’re relaxed, if you have any physical constraints where you can’t necessarily turn something that is getting heavy with scraps, you don’t have to.

There are certain tools like tumblers that are designed to roll and mix with the help of a crank, or it’s the shape of a wheel and you roll it down the sidewalk. And you can do that with a bucket. Turn a five-gallon bucket on its side, roll it down the sidewalk, and you’ve got your DIY tumbler.

IRA FLATOW: What’s this method you call lasagna compost?

REBECCA LOUIE: Makes me think of lasagna. It’s so exciting. It’s just layers and layers of all the good stuff that equal compost.

So what I love about lasagna gardening, especially for small spaces, is that you can be strategic. Let’s say you have a raised bed outside that you’re trying to fill up, right? You put your layer of browns, again, your paper, your leaves, your cardboard, shredded, increased surface area, microbe activity, blah blah blah. You put your browns, you put a layer of greens, then you might put a layer of already existing soil, which then inoculates kind of the world around it with the microbes and the goodies.

You just keep going. Lasagna, lasagna, lasagna. Layers after layers, and in time, it decomposes, and you’ve got an amazing raised bed full of good soil.

IRA FLATOW: Wow. Let’s go to the phones. Let’s go to our nation’s capital. Kelsey in Washington. Hi, welcome.

KELSEY: Hi. I have a small stainless steel composting countertop bin, and I use mostly fruit scraps and egg shells, and my bin got maggots, so I’m wondering what I did wrong and if I can save it.

REBECCA LOUIE: Did you put any meat or anything in there, or no? And does it have a lid with a screen of some sort?

KELSEY: It does. It has like a charcoal filter built into the lid, and I might not have been as diligent as I should have been with washing my egg shells.

REBECCA LOUIE: OK, well, the function of those kind of countertop bins is not so much to have the composting happen in it, but to be sort of like a holding vessel so that you carry your compost outside or to whatever system you use. One thing you could do is that if you plan to keep things on there for a long time is to freeze your scraps before you put them in. Freezing is a great way to kill pest eggs and all sorts of other things that are on the surfaces of the food that you have, so that if you wanted to place it back in the bin after freezing it, there’s less of a likelihood that you’d have some sort of bloom.


KELSEY: OK, thank you so much.

IRA FLATOW: Thank you, Kelsey. Just to remind you if you’re joining us, we’re talking composting with Rebecca Louie, author of Compost City– Practical Composting Know-How for Small-Space Living. From the kitchen counter to community composting and beyond, lots of the phones are lighting up about compost. Let’s go to Alan in San Francisco. Hi, Alan.

ALAN: I am looking at about 20 fruit flies on my little composting bin here. We’ve got mandatory composting, which I think is great. But my kitchen periodically breaks out with masses of fruit flies. Is there any way to get rid of them other than spraying my whole kitchen?

REBECCA LOUIE: Yeah, don’t spray your kitchen. There’s a really easy fix. If you take some apple cider vinegar and pour it into a bottle and leave the top open, thus creating kind of like a narrow entryway at the top of the bottle and then like a whole, you know, world inside the bottle, the fruit flies will actually be naturally attracted to it.

There’s sort of some adaptations you can do to ensure that the flies don’t fly right back out the top. You can create a cone out of paper. They fly into the cone, they can’t get back out because the cone has expanded in the whole of the bottle. But that’s a really great way to do it.

In addition, there are tapes, like fly tapes, that you could put up. And there’s sort of a range. Some are see-through. Some are thick and fat. Some are swirly, like whatever aesthetic works best for you. You can tape up those flies as well.

IRA FLATOW: All right, thanks for calling. Hope that works for you. What’s the number one newbie fail when it comes–?

REBECCA LOUIE: All right, so the fail comes to messing up that recipe, right, that relationship between the greens and browns. Everyone has tons of food scraps, and they don’t think about the dry carbon-based material, so they’re like, yay, I just made a dinner for four vegetarians. I’m going to just put it all in there and it’s going to compost. But it won’t do it right unless you add the carbon dry materials. It soaks up the water. It creates the right balance inside, the right home for microbes, et cetera.

And what results is sort of like the disaster compost story. It stinks, it’s mucky, it’s like creatures are jumping out at me. And so the best way to avoid that, like any recipe, your favorite cocktail, your favorite cookies, follow the steps to the recipe to find the right balance.

IRA FLATOW: Let’s go to Marty in Ellensburg, Washington. Hi, Marty.

MARTY: Hi, thanks for taking my call. I’m [INAUDIBLE] my worms in my worm bin, and I’m not sure why, but I’ve ended up with a whole lot of dried up tea, worm tea, and I’m wondering the best way to reconstitute that to use it, assuming I can?

REBECCA LOUIE: So when you say worm tea, do you mean that you were feeding your worms, some water, liquid, was collecting at the bottom, and that was the worm tea? Is that what you’re–

MARTY: Yeah, the worm tea is all that stuff that collects at the bottom. I never fed them water, but–


MARTY: –the worm tea was there.

REBECCA LOUIE: So here might be some sad news, which is that I know that many of these commercial worm bin things have special spigots or a way to collect worm tea, but if your bin has enough water so that it’s– or I’m sorry, liquid, that it’s leaking, you’ve actually probably overfed them and you haven’t found the right balance. And that in itself will create anaerobic conditions. It will create ammonia. It’ll create odor, and it could make your bin hot. All these things can kill a worm system. So really, when it–

MARTY: That’s why I keep killing it.

REBECCA LOUIE: You keep– you’re excited, right? They’re like your pets. You love them and you want to feed them. But that always goes wrong, no matter what kind of pet you have.

So really, I am a big advocate of portion control. I think if you start another worm bin, for every pound of worms you get, which is about 1,000 worms– that’s like the commercial going rate, 1,000 worms– but start with a cup of food at a time. And watch, see how quickly they eat it. And once that is almost gone, that is the only point at which you should feed them again.

IRA FLATOW: Good luck to you.


IRA FLATOW: Thank you.


IRA FLATOW: You live in New York, and for people with small apartments, having a bin full of worms doesn’t sound ideal.

REBECCA LOUIE: I mean, doesn’t it, though?

IRA FLATOW: There’s another method you called bokashi. Tell us about bokashi.

REBECCA LOUIE: So right, I mentioned bokashi earlier. It is my favorite thing to do right now, and I’ve actually adapted in a couple of office spaces and in apartment spaces. And essentially, you’re taking a bucket, which is airtight, so unlike the other systems we’ve described, there are no holes for air.

And you place layers of food scraps– and this can be any food scrap. It’s super forgiving. Your bones, your meat, your dairy, your mystery items, the back of your fridge.

And you inoculate them, layer by layer at a time, with special dry material that’s been inoculated with a collection of EM-1, which is effective microbes, formula one. It’s some lactobacillus, it’s some phototrophic bacteria and yeasts. And this special trifecta of microbes does amazing work to ferment that food waste, which you can then bury in any soil system, like in a local garden or in your backyard.

IRA FLATOW: I’m Ira Flatow. This is Science Friday from PRI, Public Radio International. Leaning almost all there is to know about composting with Rebecca Louie, author of Compost City– Practical Composting Know-How for Small-Space Living.

It seems to me– how amazing, people are lighting up the phones talking about this.


IRA FLATOW: I mean– let me see if I can get one more call or two in here. Jeff in Brumey, Texas. Hi, Jeff. Boerne, I’m sorry.

JEFF: Boernie, that’s right. Hi. I’m a avid home-brewer. And when you make a batch of beer, you’re left with about a two-quart yeast cake on the bottom when you pour the wort off and it becomes beer.

My question is, I’ve been pouring that in my compost pile. It just seems like it would be a lot of microbes. And I’m wondering if there’s any added benefit, or do you know, to my compost pile?

REBECCA LOUIE: And the compost pile’s outdoors, I assume?

JEFF: That is correct.

REBECCA LOUIE: Yeah, I think it should be good. You know, I don’t have specific experience with brewing yeast cakes. But the organic element is fantastic. People put all sorts of things in their compost bin, like some people do urine. There’s a whole [INAUDIBLE] movement. And essentially, as long as the organic materials that you’re mixing into your pile are complemented with the right amount of dry materials, for example, again, the carbons, the leaves, et cetera, and you find balance, you should be good to go.

IRA FLATOW: All right. Thanks for calling. Can you put– how shall I put it– dog poop into your compost?

REBECCA LOUIE: So you can. And, you know, the digester, which is sort of the submerged system that I mentioned earlier, is a great way to compost your dog poop. I wouldn’t mix it into any piles that have any intention of being anywhere around edibles.

Obviously, dog feces can have certain parasites to consider, so hot composting, which happens if you find this kind of very specific ratio of volume and mass, et cetera, will kill off pathogens. But it’s something that can be done. So these doggie digesters, where you just basically throw it into a tube in the soil, become quickly populated with earthworms and such that want to break it down.

IRA FLATOW: How do you keep it going over the wintertime, your pile outside?

REBECCA LOUIE: So keeping it going over the wintertime isn’t so much a thing if you’ve got real winter. You know, like all science, when the weather gets– when temperatures drop, microbes slow down. The reason why bokashi, again, is attractive is that because you’re fermenting in bucket, it can be indoors and anywhere. And come springtime, the fermentation has occurred over the set period of time so you can be good to go starting spring and then collecting buckets over the winter. Similarly, a system like a worm bin, which is easily kept in your home, in the closet, under the sink, under your bed, is a good way to keep it going, as well, because temperatures are regulated.

IRA FLATOW: Rebecca, thank you very much for taking time to be with us today.

REBECCA LOUIE: Thank you so much for having me.

IRA FLATOW: You’re welcome. Rebecca Louie is founder of the blog Compostess and author of Compost City– Practical Composting Know-How for Small-Space Living. We’re going to take a break, and when we come back, ancient ungulates.

Grizzly bear suits is the topic of our latest video about the musk ox, how to sneak up on a musk oxen heard and survive to tell the tale. Well, tell me about the guy who does that for a living, and Luke Groskin will be here. He went along and made the video. We’ll talk about it after this break. Stay with us.

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Alexa Lim was a senior producer for Science Friday. Her favorite stories involve space, sound, and strange animal discoveries.