[Retrospective] Vineyards Special #1: The Wonders of Cover Crops

EPISODE SUMMARY

While we will continue to make new episodes, there are times when we feel the urge to highlight a past episode – because the topic it covers becomes news and the show shares some great insights, or because it is content that our newer listeners might have missed out on. Since last year was the International Year of Soils, we will be republishing a few of our best episodes about soil and soil health to get a fresh perspective in light of all the progress that has been made on the issue.

To round-off the series, we’re ending with a in-depth look at a popular and very effective sustainable agricultural technique: cover cropping. In episode 16 of our show, we had with us Bob Cannard and Bob Shaffer – both experienced sustainable farmers and horticulturalists. They shared their techniques with us, explained just how cover cropping works and how beneficial it can be, and gave us their expert advice. We learned a lot about cover crops in making this episode, and if you’re wondering after the last two episodes, just what exactly the sustainable agricultural techniques might look like that we need to start pushing for – this is the episode for you.

Links to other episodes in the Series:

Episode 1

Episode 2

Episode 3

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Photo by Robert Reed, courtesy of Recology.

Cover crops are becoming more and more popular, but they still aren’t completely understood by everyone. Bob Canard, can you tell me what exactly cover crops are, and how do they work?

Bob Cannard: Cover crops are nature’s way of preserving, enhancing and balancing the soil. All they are, are crops that grow naturally, or are planted, that are allowed to grow and establish and protect the soil, cycle nutrients and actually build soil, absorb atmospheric carbon, deposit it in the soil as food for the soil biology, which is the important digestive force of all life.

Bob Shaffer: Yes, cover crops are simply plants. Now, we’re going to chose the genus and species of plant that we call a cover crop, or, as Bob said very brilliantly, we can also just accept the resident vegetation – that which is growing in a field or pasture. But let’s recall that plants are the organism on earth that harvest carbon out of the air and puts that carbon into a form that we call organic matter. So plants are literally producing organic matter on earth that we then can introduce into the soil as a carbon source, which is food for microorganisms and other animals, and then also the plant above ground is protecting the soil surface.

Where are cover crops most popular?

BS: Cover crops are being used every place around the world right now, more and more every time. I’ve watched Napa and Soma Valleys (California), as I’m sure Bob has also, become quite well cover cropped compared to ten or fifteen years ago; they’re more and more used all the time every place.

Bob Cannard, as a long-time cover crop user, can you tell us the key benefits of using cover crops, as opposed to mulches and other methods?

BC: They stimulate the soil biology: all plants produce lots of sugars and other complex organic molecules that they pump into the soil and establish a relationship with the soil, so they actually nurture the soil. At the same time, their root system breaks up (subsurface soil compaction), and cycles nutrients from deeper profiles to the surface, making the soil more aerobic and balanced towards aerobic life – which it’s all about.

By comparison to mulching, they grow many cubic yards (depending on the intensity and the size of the cropping system) of compost for the soil. And mulching – you’re getting that organic material from another piece of ground, and it sacrificed its organic material to turn it into mulch or compost, which is spread on the ground, and it takes a lot of BTUs of petroleum energy in order to do all of that and spread it. Whereas the cover crop is very low energy input: the seeds are planted and they grow, and they harvest that atmospheric carbon, and deposit directly into the soil without those heavy inputs.

That’s a very interesting benefit.

BS: It’s very expensive to grow mulch on one piece of land, take the carbon from that land and move it over to another. We’d like to grow and use the cover crop as our source of mulch.

Bob Cannard, you manage hundreds of acres of vineyards that use cover crops successfully. Can you tell me a little about your strategy and what cover crops you use?

BC: We have a thousand acres in cover crops. Every winter time is the rainy season, and we plant in the fall after harvest, or just before harvest. We used mixed seeds and I’m a great proponent of a mixture of cover crop plants.

First off you need very low energy, quick germinating nurse plants that hold and protect the soil for the higher-level life support plants that come along slower and later. The cover crop protects the soil from all kinds of erosion, and the little quick growers do that quickly. They don’t provide too much organic matter, but they really help the next stage, and the next stage is perhaps the low proteinaceous broad-leaves, and then you’ll phase in to the higher proteinaceous grasses – more and more biomass. And finally, the high level of life, long term blooming plants, like the clovers and the vetches and the peas and the beans – the leguminous plants that take much longer to mature. Each one helps the next one, and the diversity is a very important element.

We like to grow our cover crops and let them stand to as full maturity as possible. In the organic kingdom, there’s lots of conversation about green manure cover crops; well, they break down very quickly and release lots of nitrogen. What I’m looking for is lots of carbon, and stimulating the free-living nitrogen-fixing biology of the soil, and this vastly reduces the need for nitrogenous influences, applications, fertilisers on the vineyards – and in the vegetable gardens as well.

Can you get a little more detailed about the process and tell us when you plant the seeds, how you cultivate it – if you do at all – when you mow it, and how you manage it all?

BC: Well, it depends entirely on the site. Some sites, hillside sites, are never cultivated and the cover crop leans progressively more towards perennial plants. Other sites are cultivated, but we do our best to cultivate as late as possible, allowing the cover crop plant to come to its maturity. When you try to incorporate a green plant, like a green manure, it has only lived a portion of its life and it has a high nitrogenous body; whereas if you allow to as great a degree of maturity as possible, it dries out, it makes its own seeds (some varieties reseed themselves and don’t need to be included in successive plantings), and it’s straw is carbonaceous and has a longer than one year half-life in a temperate climate. So you actually build soil carbon, the foundation of the soil digestion, which is an absolutely critical motion. Everything has to have good digestion, and that digestive force solubilises the minerals. Additionally, on the soil surface, that straw spawns and sponsors the various yeasts, so we are less dependant upon yeasting the pressed grape juice to make wine, and we can use the indigenous yeast of the particular site in many cases which means we get the true terroir, or taste of that soil and that location.

To be clear about the general process of cover cropping: you plant the seeds, either in spring for summer cover crops, or in the autumn for winter cover crops. You can use it as a green manure by mowing it and incorporating it into the soil when usually when it’s flowering and still green, or you can wait until it’s a little woody and chop or mow it down to use as mulch. Is that correct?

BC: Yes, it’s mowed down or grazed down, and maybe cultivated, or maybe just mowed and grazed – it depends upon the plot and the variety, and air drainage, and many, many variables. We’re always trialling little plots of little pounds of sprinkling here and there, and it takes a while to grow the soil; if you have a herbicided, clean cultivated, long-standing degraded soil, high level of life plants like clovers may not take hold, because it doesn’t have properly developed soil biology yet. But through the use of incorporating the maturity of the cover crops over seasons, the soil population will change and you’ll get the nice, soft, beautiful, proteinaceous, easy to work with kinds of plants, and they will take over from the thistly, thorny, creepy-crawly, difficult types of plants to manage.

So viticulturalists should be prepared to invest a bit of time at the beginning if the soil isn’t healthy already. And is there anything specific to vineyards that viticulturalists need to understand about cover cropping – is it much different to cover cropping for farms?

BC: Not particularly, but the height of the type of plant and whether it’s an annual cropping cycle or a perennial, and its degree of maturity so that it can become reseeded, so you don’t have to reseed it annually – at least not with all of the species…

We use early season grazing of sheep and goats at high density, quick rotation so that they aren’t over-grazed but just appropriately grazed. The sheep actually stimulate the regrowth of the cropping system, so it responds as the season advances into the summer time with a good early maturity. Then, in many cases where it’s just mowed, what you end up with is all of this reflective strawy grass on the soil surface – not just grass but all the plants that turns golden as it dries out – and it reflects heat back up to the fruits underneath the canopy and actually increases the warmth and the dryness of the canopy. This reduces the incidents of mildew, and stimulating this broad array of canopy biology that additionally enhances the resistance of the plant through species competition of one dominant mildew type problem.

That’s a unique benefit of cover cropping, or mulching. And Bob Shaffer, do you want to add anything? 

BS: We have to recall that viticulture is a monoculture, often times at least, and I see the cover crop as a way to bring diversity, and to break the problems that are associated with monocultures. Also, I can rotate the genus and species that I use; I can rotate them over space, I can rotate them over time, so it actually adds, not only diversity to the monoculture, but adds the component of rotation. For example, I can put perennials on one side of the vines or tractor rows; I can manage that as a perennial cover for a few years, and then I can have annuals on the other side. I can also use those annuals and/or the perennials – or specific strips planted through the vineyard – as a beneficial habitat and food sources for beneficial insects, beneficial life forms in the vineyard. So, in all ways, the cover crop – if selected and managed well – can be the source of diversity, can be the source of rotation, and the source of beneficial life forms brought to the vineyard.

There are many variables when it comes to cover cropping, and there is no “one-size-fits-all” approach, but is there something you would recommend to everyone starting off with cover cropping?  

BS: It’s something that teaches you. I’d encourage people to immediately start cover cropping, and all farmers must always have trials going on. These do not have to be large, expensive, exhausting procedures, but having some type of trial always going on in the farm shows you where to head next. It also is your little classroom where you can go out and look and learn. So having at least some strips of cover crops – of different species always – to learn what to plant next is a good idea.

There are a lot of species to choose from as well. Bob Shaffer, what are your thoughts on choosing the best species for vineyards?

BS: On choosing species, one of the things you want to do, as Bob Cannard pointed out, you want to use a polyculture. I’m always going to use a mix of grasses, legumes and forbes when I’m planting. Also, as we broadcast it or drill this type of mix, the site itself will sort out which plants are most appropriate there.

In frost-prone vineyards, cover crops may the increase in risk of frost damage. What is your advice regarding this?

BS: Certainly if I’m going to put a cover crop into a frost prone vineyard, then I’m going to add the important component to the cover crop that we haven’t directly mentioned yet, which is as important as species selection, or any other feature of the cover crop: the management of the cover crop. So, if I have frost concerns, I’m going to select cover crops that are low growing, and then I can manage the cover crop in the frost season by further mowing it – at least on one side of the rows to allow some air drainage. Also, if you’re using broad-leafed species, they tend to have less of the ice nucleating bacteria on their leaf surface, and are less prone to causing frost problems in the vineyard or orchard.

I want to address another common worry that people have regarding cover crops, which is water usage. Wouldn’t cover cropping add extra irrigation costs for drier climates?

BC: We grow over-winter cover crops and we utilise rainfall as a natural irrigation, and it actually increases rainfall infiltration by reducing soil compaction. So actually, we reduce irrigation requirements; and then, it’s depositing on the soil surface at maturity, high levels of carbon, and one unit of carbon will support and hold approximately eight units of water. So, we increase our water holding and infiltration characteristics by increasing the organic matter content and the root zone development through cover cropping.

Yes, I read in a couple of articles, including a 1994 research article in the California Agriculture journal, that winter crops generally have very little impact on soil moisture compared to summer cover crops – so that would be a good option for vineyards. And Bob Shaffer, do you have anything to say about water usage or to add to Bob Cannard’s point?

BS: The cover crop, particularly because of its roots being in the ground, increases the humus levels. As those roots decompose, it increases the humus level, and this is the material that Bob Cannard was referring to as holding more water in the soil.

Though I will say that, sometimes if I have an existing vineyard, maybe it’s old and maybe the soil is weak and worn out, the transition period of introducing cover crops into that vineyard – there has to be some care taken to make sure that we don’t take water away from vines. Obviously, a cover crop plant uses some water when it grows, but it’s more an issue of timing: both timing in terms of transitioning into a cover crop (where the vine gets used to having other roots around it) and also as we build humus in the soil, there’s a little transition time that’s needed for that. And then, if we use a little water in the spring time for the cover crop, that doesn’t take away critically from the other crop – whether it be vines or some other plant; but later in the year, as the cover crop has been managed into a mulch, we’re actually using less water because we’re protecting the soil surface, we’ve built humus in the soil… And so, the timing issue on water needs to always be addressed rather than saying “okay, does the cover crop use water or not”.

So the takeaway from this is that timing is everything and it may increase water usage at the beginning, but in the long run it will actually save water. And now onto the management question: I presume it takes a little more time and effort to manage cover crops – wouldn’t this increase management costs?

BS: Considering whether cover crops raise our management costs, we have to look at the whole farm, and look at the multiple benefits that the cover crop has brought to the farm to address whether we lost or benefitted in terms of management dollars.

Can you both give me some examples?

BC: Well, my field, these vineyards that I assist in managing were conventionally grown and heavily cultivated, and herbicided underneath the vine rows. And we had, when I first took over twelve years ago, a preponderance of tenacious, noxious weeds that interfered with the canopy of the grape vine, and through management of the cover crops – planting selected varieties and improving the soil, and utilising inter-crop grazing of the sheep and the goats – after twelve years now we have very few noxious weeds and it’s actually reduced our over all costs; weeds that would shoot up from the herbicided strip into the canopy that had to be mowed or supressed in one fashion or another.

BS: Another aspect of management that cover crops can safe you money instead of cost you money would be for dust control, for example. A lot of times a vineyard or farm will get very dusty during the dry season, whereas if we have cover crops and we’ve managed over to stubble and/or mulch on the surface, it reduces dust. That dust can increase mite pressure in the vineyard, so if we have mulch and we’re absent of the dust, then it decreases our cost of spraying for mites, or managing for mites. There a number of other features that we could name that the cover crops actually decreases management costs.

One of the benefits I came across was the introduction of beneficial predator insects that keeps pests down. Has that been your experience?

BC: We’ve had very few problems with pests.

BS: Certainly, if you provide habitat and food for everyone, then the system tends to become more balanced. Where there are appropriate numbers of predators, there are appropriate numbers of prey. As the goal in “managing the farm” or “managing pests” is not to eliminate all the pests; it’s simply to increase the antagonism from the pest’s predators. And we do this by carbon, we do this by having flowering plants; nectar, pollen, habitat, and carbon above ground.

If anything, I’ll say the cover crop, with all the glory that we’ve talked about and the beauty of the cover crop, still: the cover crop shouldn’t be viewed as all we need; we always have to look after the whole system and say “okay, look: I’m going to manage organic matter, which includes cover crops, compost and mulches. I’m going to manage minerals. And I’m going to manage my tillage”. Those three areas: OM management, mineral management, and tillage management all need to be considered, all need to be cared for to have the cover crop show its best; to have the compost to show it’s best, and to have the minerals show its best. They’re linked in biology, they’re linked in being foods, and they’re all necessary to manage at the same time to get the best benefits.

So a holistic approach is really what you’re going for. And are there any other benefits to using cover crops that would outweigh other management costs?

BC: The cover crop and the soil surface organic material holds and supports the soil, where many clean, cultivated and just bare soil surfaces can be very tacky. Let’s say during harvest we have modest rainfall, then it impedes the ability for the harvest crews and the equipment to move through the vineyard because of the muddiness, whereas with the increase of soil surface organic material (and especially the dry carbonaceous material), the soil surface is held and supported by the residual root systems. And the soil surface itself is protected by the strawy organic material, and this really reduces the stickiness in many different ways: just physically at a large-scale straw level, and at a digested carbon level/humus level it allows the soil particulate matter to be happy with itself and want to stick to other elements, such as harvesters feet

That’s an interesting benefit that I wouldn’t have thought of, actually.

BS: That’s actually a huge benefit, even during the year sometimes with the irrigation systems, if you have cover crops it enables workers to have less mud on them, and to have some place to sit down; to have some place that’s green and flowering instead of just a bare herbicided soil. There’s a huge difference in the vineyard for both the people and the crop when we use cover crops.

We’ve covered a lot of ground in this episode already, although we could probably go on forever. But for the final question: are there any issues you want to address with cover crops, or anything else that viticulturalists need to keep in mind when cover cropping?

BC: Well, it’s a possibility that you might have overgrowth. A lot of viticulturalists, back to frost issues, are worried about canopy heights of cover crops. Well, there’s legitimacy to this, because it reduces air drainage, but at the same time, a high-density cover crop of good, bread-leafed plants has a better canopy biology to it that resists frosting. And those plants are also respiring energy and actually warm the vineyard’s atmosphere on cold nights.

No, there are definitely problems, and it’s a progressive activity. A novice viticulturalist beginning to grow cover crops might be afraid to let them come to maturity, and boy, that’s all right – it’s a beginning. And as we develop and grow, we develop more confidence as we grow, and we also develop our soils and select a broader diversity of cropping specimens, a variety, and allow them to come to greater maturity.

BS: That’s certainly experience speaking, and I’ll say to summarise that excellent comment by Bob Cannard: I would encourage people to view cover cropping as a transition, as part of a transition into more healthy soils, and to better above-ground relationships, rather than an instant change.

Well put. So, cover cropping is definitely beneficial, it just takes a little bit of time and a little bit of effort to get it all going. But once you have the experience, it’s probably the best way to go. Unfortunately that’s all we have time for I’m afraid, thank you Bob Cannard and Bob Shaffer for coming on the show.

BC: Well, thank you for your interest.

TRAILER – Water & Carbon: 3 New Answers to the Water Crisis in California and Beyond

Our editorial team is currently producing a 6-episode series of The Organic Stream talk show, dedicated to spreading strategic insights to influencing bodies and support drought relief efforts in California and other regions of the world facing a water crisis.

Until today, the focus of the water crisis in California has been on conventional strategies and short term actions, instead of outlining solutions and creating a debate that ties to the broader picture of water, waste, carbon and energy management.

The Organic Stream team traveled the length of California to collect insights from the field and work with key players from the agricultural sector, compost industry, scientific community and public sector in crafting a new narrative. A narrative that ties together several of the challenges the state is facing with food production, water management, waste management and climate change to provide clues on how an integrated approach to resource management can dramatically change the game for the better and for the benefit of all.

The show will blend expert interviews, storytelling, narrated content,  soundscapes and music. Each episode is approximately 30 minutes.

 

 

Drought Special: Communicating Compost’s Magic in Our Cities

This episode corresponds to Lesson 3 and Lesson 4 of our online course.

Episode thirteen is part one of a three-part special on the drought currently experienced in California, and the value of compost for saving water. In this episode we’re talking to Robert Reed on how cities can prepare for drought through awareness campaigns that highlight the water-saving benefits of compost use.

Thank you to Recology for making this episode possible.

Recology is an employee-owned company operating in California, Nevada, Oregon and Washington coordinating dozens of recycling programs to recover a variety of materials. In San Francisco, they are part of the program Zero Waste by 2020 and are very involved with compost production and distribution. Visit their website here.

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EM: So Robert, I know that there’s a lot of talk about California right now, which is experiencing one of the worst droughts on record at the moment. The Governor declared it a state of emergency, and has signed a 687 million dollar drought-relief package into law. Farms are suffering, and people are being urged to reduce their water usage by up to 20%. So, it’s going to be a tough summer and people are doing all they can at the moment to help save water. What are you doing over at Recology to help the effort?

RR: Well, we’re trying to help people understand and know that compost saves water, and that by participating in our curbside compost collection program, people can help California save water. Compost by weight is fifty percent humus, and humus is a natural sponge. And farmers understand this, and they’ve purchased a whole lot of compost from us in the last six months, to put it on their farms in an effort to retain more rainwater.

And, at Recology we’re trying to help people understand the ability of compost to help capture and retain water. In the city, the traditional reasons to participate in the curbside compost collection program are to keep materials out of landfills, and return nutrients to farms. And almost everybody understands the first one; everybody gets that composting is a good thing to keep material out of landfills, and to have less landfilling going on.

I would estimate that about half of the people in San Francisco are connected and understand the second motivation, which is to return nutrients to farms. And now, we’re trying the emphasis a third reason to compost all of their food scraps, all of their plant cuttings, and this third reason is to help save water, and to help California – the state that we love – do better in terms of mitigating the drought.

EM: Yeah, excellent. And I presume getting people to understand that last one is a little more difficult, then?

RR: Well, for people in the city, it’s a new idea and so, when you have a new idea, you need to get it out there a lot, you know. You need to get it on the internet, you need to write about it, you need to do TV reports about it…you need to put it in your newsletter on your website…. It just helps of people hear it multiple times from different sources.

We’ve worked a lot with some agronomists to help get the wording right, get the research correct, so that we can frame the message correctly and accurately, and then help communicate this, about how compost helps save water. And we’ve written an article, and we’re going to publish it as the lead story in our customer newsletter next week. We also shot a photograph that shows some hands holding a little young plant – green with water on its leaves, and of course the compost in the picture is very wet, and very heavy with water. So we have an iconic image that helps people…they can look at it and they immediately understand this point, that compost and the humus in compost is a natural sponge. Pictures are very powerful, and so this image is important, and we want to present this image in as many places as possible – and the message.

Mh-hm, right. And as part of your outreach campaign, too, you host an annual compost giveaway in various locations around the city for people just to come and collect compost, is that right?

RR: Yes, and it’s absolutely a joyous community event and it’s a bring your own bucket event, so people will bring two five-gallon buckets, and we’ll fill them with compost that they helped make, and they take it home and put it on their gardens, and on their outdoor plants. And, you know, this is the kind of thing that you can do when your city has a compost collection program. You know, not only can you keep materials out of landfills; not only can you send nutrients back to farms; not only can you help the region and the state that you live in save water – but you can also help create a compost that then comes back to your city, that residents can get through a compost giveaway; they can use in their own gardens; and that can come back to community gardens in your community; and can come back to urban farms in your community.

EM: Yeah, exactly. But now I’d like to get down to business and talk a little bit more about campaign strategies – can you tell us what you think makes for successful awareness campaign and public outreach strategy?

RR: Well, you have to go straight to it and say, you know, “compost to help save water”. And people kind of subliminally understand these things; it’s a very old understanding for people. All of us have gotten our fingers into the soft soil in a garden at some point in our life. And so, when we present a picture that shows compost that’s heavy with water and it’s very dark, it rekindles this subliminal memory in people.

And so, it’s our feeling that people need to see this picture and hear this message. They need to see it in print, they need to see it online…one of the points here is that the outreach and education around composting and recycling is competing with a lot of other information that’s in your community, that’s on the news.

There’s just all kinds of information out there that’s competing for people’s attention. And so, composting has to be part of that discussion. Composting has to be part of the game, so how do you make all this good information; this positive information about composting…how do you get in the game?

EM: Mh-hm, right.

RR: And one of the things is what you mentioned, is that the leaders in the community need to be talking about it, and concerned about it. And they need to attend the compost giveaway; they need to talk to the media about it; they need to hold a news conference about it periodically, or pen an article or an op-ed that gets published in the city’s newspaper. So, you need to do creative things. And one of the things we just did at Recology is we came up with a playful recycling quiz, and we posted it on our website.

EM: Yeah, I saw that actually, I thought it was very funny.

RR: Yeah, well okay, I’m glad you enjoyed it. You know, we…it’s a series of nine multiple questions – what goes in the blue bin, what goes in the green bin. And of course the first answer is something completely ridiculous, and then the second option is something frustrating or annoying. And then of course the third answer is the correct answer, and it’s something you might not have known that you could compost – like soiled paper.

EM: Yeah, and I particularly like how you actually explained in your newsletter about the soiled paper – that it’s great for compost. And that you call the short paper fibers that organisms love to consume – y you called them carbon candy. I think that’s a great way of framing it.

RR: Yeah, and those are the kinds of stories that we need to tell, and we need to particularly tell them to younger people. The Union of Concerned Scientists did an analysis – they looked at all the message about recycling and about composting: should the outreach dollars be spent on radio ads, or TV ads, or bus shelters, you know. And they measured for the first time in the history of America; really, they did a very complete measurement of what is the most effective way to communicate about recycling and composting. And the answer…what they discovered was that the best thing to do was to communicate to students and to younger people.

They reported that we all know that kids learn to recycle at school and then go home and teach their parents. What this research proved was that parents are actually listening to the kids. So when the child goes home and says, “Mom, we compost at school, dad we compost at school – why don’t we compost here in our kitchen at home?” Then the parents are listening and the family will then get a kitchen compost pail and start composting more of their food scraps and their plants at home, and increase their participation in the composting program.

EM: That’s very interesting.

RR: Yeah, it’s very interesting. So, we’re trying to tell the story of carbon candy to kids. We’re making presentations every week to students in classrooms in San Francisco. One of the reasons, you know, that we did the playful recycle-compost quiz is to do something entertaining, and we’re going to let all the schools know about it. And that’s what we’re doing in California.

The farmers are joining us. The farmers have come to San Francisco and held news conferences, and asked people to be more attentive to put all their food scraps and plant cuttings – and soiled paper – in the green bins, so that we as a community can make more compost and we can get it onto farms, and add life to the soils – return life to the soils to help protect our topsoils. This is very interesting: farmers coming into the city, holding news conferences; asking people in the city to do right by the environment, to compost more of their food scraps.

EM: Very good. And for the last question, now, I’d just like to get your thoughts on the drought and how it looks for the future of California?

RR: Well, there’s many articles that are suggesting that California will not have as much rainfall in the future as it has historically. So, we have a history of dealing with dry periods; we’re going to have to remember what has worked for us historically. And, if you want to know the answers to environmental questions; what should we do to help protect the environment, what can we do to do more recycling, more composting…often the answers are in the history.

Look back: what did your grandparents do? What did your great-great grandparents do? They composted! Okay. They had an area where they would put their food scraps – they made compost. And we need to remember that as a community, and we need to do more of that. And we’re going to need to do more of that in the future.

EM: Wise words. But unfortunately that’s all we have time for now today, Robert.

RR: Alright.

EM: Thanks for coming on the show.

RR: Thank you.

EM: Alright, best of luck now.

 

Getting the Recipe Right – A Dead Cow Versus Industrial Perfection

by Craig Coker, Chairman at Virginia Composting Council

In this blog post, Craig Coker shares two illustrative stories that marked his career and describes a few basics of the composting science – or art?

Just about anything that was once alive can be composted.  The simplest compost pile I’ve built was at a farm by covering a dead cow with hay and sawdust.  Six months passed and voila, I had compost!  On the other hand, I’ve built piles at an industrial composting facility that came from fifteen different contracted materials, varying from sewage sludge to food processing scraps to wallboard.  In both situations, it was absolutely critical to get the materials proportioned properly which we will delve into.

First, a little on the science:  composting parameters include chemical concentrations of carbon, nitrogen, and soluble salts, along with physical characteristics of moisture content, bulk density and volatile solids.  These are the very factors that go into how I build my recipes. I am fond of saying that composting is like baking a cake; if the ingredients for the cake (flour, sugar, eggs) are not in the right proportions, the cake will not rise or it will not taste good. It is the same in good composting. If the ingredients are in the wrong proportions:  the carbon-to-nitrogen ratios will be off, the moisture content will be incorrect, there won’t be enough volatile solids to fire up the biological reaction, the free air space might be too low to allow good air flow, or the soluble salts might be too high to be ideal for plants.

While composting sewage sludge with wood chips and many other materials was not a revolutionary equation, it was very precise from strict parameters. At an industrial composting facility, an aeration system was utilized to blow air into piles that were 30’ wide by 100’ long by 10’ high. Composting under this forced aeration system lasted for 21 days, then the piles were broken down and moved outside for curing. Waste materials were delivered to the receipt area next to the mixing hall, where they were stored in separate piles. The loader operator working in the mixing hall had to know how many loader buckets of each material he needed to add together to make a good composting recipe. I used an Excel spreadsheet to develop his recipe. Samples of each waste material were analyzed in a qualified laboratory and then put the values for carbon, nitrogen, moisture and bulk density into the spreadsheet. I adjusted the weights of each ingredient until the spreadsheet model indicated I had a carbon-to-nitrogen ratio of at least 25, and a moisture content of at least 55%. I used the bulk density values to convert the weight to volumes.

I climbed up into the loader operator’s cab to show him the recipe. He said he had a 6 cubic yard bucket on the loader. In sum, we were able to figure out he needed to take so many buckets from this pile and so many buckets from another pile, which he fed into a mechanical mixing system. The properly-mixed ingredients were moved into the composting hall by a conveyor. Perhaps this is sounding a little too precise and calculated. And to that end, you might be wondering:  how did I have such luck with composting the dead cow?

I was running a dairy manure and sawdust composting facility at a farm in western North Carolina. One of the cows had died overnight and the farmer was planning to dig a hole in the fields to bury it. I suggested he let us compost it instead. Agreeing, he brought the animal in the bucket of his tractor and laid it down on a 12 inch thick bed of sawdust we built. I realized that the high nitrogen content of the body coupled with the large size of the cow would slow the process and risk odors, as well as vectors. I punched a couple of dozen holes in the body with a pitchfork to allow access for the bacteria and covered it with an 18 inch-thick layer of hay which gave the pile good bioavailable carbon. We watered the hay until it was damp to improve the moisture content and finished by covering the hay with 8 inches of sawdust to discourage birds and other vectors from poking around. We kept the outer layer of the sawdust wetted down when it wasn’t raining to keep it from blowing around. After 3 months, we dug a hole in one end of the pile and found a leg bone.  We left the pile in place for another 3 months, and when we dug into it, found just a few bone fragments and lots of dark brown compost… Voila!

Is compost a haphazard event?  It can be, but regardless, composting is both a meticulous art and science.  

 edited by Rachel Chibidakis