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Posted on December 5, 2013 | 11 Comments
Maybe it’s time to write something about practical farm issues for a change, and what could be more practical than compost? In principle, compost is one of those ‘what’s not to like’ phenomena. You pile up unwanted organic matter that otherwise requires disposal, mix it with a bit of air and water and, hey presto, you end up with a magical substance that feeds your next crop and builds your soil. Compost is foundational to the organic farming idea of building beneficial biological cycles into farming practice.
But the practicalities of composting raise quite a number of dilemmas. Here are five:
So, what is to be done? If I were running a small domestic garden, I think these problems would be manageable. And if I were running a large farm I’d use a big tractor and other energy-intensive kit to develop a decent composting system. It probably wouldn’t surmount the energy issue, but then nothing really does on a large farm. On the small farm, however, as with many things you get caught between two stools.
Steve Savage, a persistent critic of organic farming, decries its use of compost for similar reasons to those outlined above and advocates the use of anaerobic digestion instead. Such critics often forget that good old composted farmyard manure is widely used in conventional farming too, though perhaps only in those areas which have thankfully managed to retain a bit of mixed arable and pastoral land use and haven’t yet succumbed completely to the depressing uber-specialisation wrought by big agri where soluble synthetic fertiliser is king. Still, Savage has a point – in an ideal world, a digester is probably the best way to go. But then the argument tends to drift in favour of massive dairy farms or feedlots with ‘efficient’ industrial-scale digester facilities. I don’t know if there are any good energy lifecycle analyses of such facilities, or of large-scale mechanised farming machinery powered by methane, biodiesel or renewable electricity but if anyone could point to me to some, I’d be grateful. My feeling is that the whole-life energy costs, including building these big plants and then trucking the raw materials around, would be pretty high. Likewise with the opportunity cost of a fossil fuel-free industrial-mechanical agriculture would be high. But I’d like to see some good data. As I’ve suggested before, there are many other external costs of large-scale agriculture that suggest to me the wisdom of small-scale farming solutions, but I don’t deny that compost and fertility cycling is a problem for farming of all kinds which isn’t simply banished by scale.
One alternative for the small farm is a small-scale, backyard digester of the sort pioneered in China. My worry there is that if the facility isn’t very well built the chances are it’ll leak methane and lose its advantage, and to build it well may take more time and money than the average small farmer can really afford. But it’s a technology I’d like to keep my eye on. Some people coming from a vegan perspective are excited by such technologies as a means to turn grass into something useful without livestock. Call me old-fashioned, but personally I prefer to see ruminants on grass in mixed farming systems, though again it’s an intriguing idea and it would be worth seeing a good lifecycle energy or emissions analysis.
Anyway, the compromise strategy we’re currently pursuing at Vallis Veg is a much lower tech one. It has the following components:
It’s not perfect, but it’s the best I can currently think of. As always, I’d welcome any comments.
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I wonder if you have ever looked into bokashi composting? Don’t know much myself, but going to look into.
The approach I am most interested in is radial branchwood mulches. I read about this in a book from the Vegan Organic Network. Apparently mushrooms/mycelium only need 1 part nitrogen to 14 parts carbon – as opposed to 50:50 for bacteria such as those that drive composting. So the approach goes, put a thick layer of fresh chipped branchwood and leaves (higher in nitrogen) down, mixed with leaf mulch from woodland to get mushrooms started. Then feed with a shallower mulch, as part of no dig (I am thinking to try this with Charles Dowdings approach, replacing manure).
Woodchip is a widely available as a waste product (though maybe not with lignified heartwood separated out..), and given time it composts into lovely rich stuff simply mounded up. But there is a design reason for using this, and it’s the same reason for not using peat. If we are serious about sustainability, we need to design systems and develop techniques that can be scaled up. Animal manures especially horse manure cannot be expected to fit this, plus being linked to carbon intensive foods and animal welfare issues. Even better, radial branchwood is produced in abundance through coppicing. The icing on the cake is a steam (woodchip) powered wood chipper.
You might be interested to hear about some self build micro anaerobic systems.
From an old water boiler:
http://www.communitycompost.org/index.php/projects/mad/46-mad
A group who did a talk at the UK Permaculture Convergence are aiming at a kit using an adapted IBC for under £1k (can find who).
Urban Farm Guys have a system made from barrels: http://theurbanfarmingguys.com/category/biogas
Thanks for that UGP – interesting stuff. I’ll follow up on it. We seem to get quite a lot of leaves and branchwood in our woodchip and I’ve certainly noticed a lot of fungal mycelium in it. I agree with you about scaling up sustainability, though I think of the compost as a bigger issue than the peat in volumetric terms. Anyway, as I say I hope we can move to seed compost from the woodchip at some point. Not sure I’d be happy to give up on my leys and go completely no till though.
Rotations between crops and legume-rich pastures seem super sustainable to me, as much for their weed-control benefits as for nitrogen, some of which will presumably be lost before your crops get it. How much of your farm is in leys each year?
Hi Ford, sorry I somehow missed noticing your comment. Yes, I often wonder about nitrogen loss from the tilled ley – do you have any good data or analysis on this and of how to minimise it? The tilled areas are about 20-25% leys, albeit with some crops sometimes established in the ley. But we also have quite a lot of permanent pasture, the aim being to do a better job long-term of transferring some of the fertility from pasture to crops. I’d be interested in your views on this.
Chris, I think your sheet composting makes a lot of sense, at least in terms of building soils, which benefit from the process of decomposition when it takes place in/on them, rather than in a compost pile. I think there are only three reasons to make a compost pile; 1) to reduce bulk to make transport less expensive, 2) to kill weed seeds, and 3) to reduce pathogen levels if that is a concern.
Thanks for commenting, Andrew – glad to have your confirmation that it makes some sort of sense.
Chris, I wonder if you ever followed up on UGP’s bokashi suggestion. I’ve been doing it for a while now, and the more I learn the more impressed I become. Here are some notes from a presentation I’m working on now. They are aimed at householders, but most apply to small farms.
What is Bokashi?
* “Bokashi” is a Japanese word for fermented organic matter
* Similar fermentation is widely used in parts of Asia and Latin America to return nutrients to soil
* The organic matter is PICKLED, not composted, retaining all of its nutrients and embodied energy
* Bokashi can be made where organic waste arises. I make mine in the kitchen.
* Bokashi is best applied directly to soil, where its nutrients and energy are needed. No intermediate heaps.
Why Bokashi?
* No more food in household bins: not only fruit and veg: bread, meat, fish, cheese, leftovers too.
* A nicer, more convenient method. No stinking bins or bags prone to maggots, flies and vermin. Primarily indoors, even a flat
* Nourish, regenerate or make new soil
* Beats composting: quicker, cleaner, smaller, less effort, more effective, no carbon emissions
* Low cost: subsidised because council saves landfill tax
Have you anything to add from the small farm perspective? The “make where waste arises, apply only where needed” principles chime with other ideas above. HTH
No I haven’t really followed up on it, but thanks for posting your thoughts. Perhaps I’ll look into it some more. On a farm scale I’d be interested to know more about the ways in which people do it in situ without intermediate heaps. Presumably it would be a variant on in situ mulching.
I immediately think of two approaches, both scaled up from garden use.
The usual in situ version is simply trench, fill with bokashi, mix with trench base and re-cover with soil. Ready in 2-4 weeks (summer-winter). Much less than compost maturing time.
This is OK as long as you can plan where you want it and the timing is right.
The other is a “soil factory”. Jenny explains quite a large scale version at https://bokashiworld.wordpress.com/2013/03/04/how-to-make-a-soil-factory/. It’s something you could put right next to your growing beds, and indeed might itself be a bed in preparation, or part of a rotation scheme. You just scoop out what you want.
I would also recommend browsing Jenny’s blog, almost the best place to go IMO – the best being the Canadian http://bokashiliving.com/composting-faqs/ and its blog posts. Both sites packed with real knowledge rather than recycled propaganda.
Chris, I’ve had great success with a humanure bokashi system with added biochar and woodchips in my garden in the past. The sheer number of earthworms feeding on the mycelium in the soil after adding it to the garden along with the usual collected rainwater/greywater was ridiculous. What a shame this system is not being adopted in cities as there is literally no smell at all. Compost is only ever meant to be a one-off effort to reintroduce beneficial organisms into the soil as Elaine Ingham is won’t to say.
What is your experience with vermicomposting if you have any? Do you think it could work on a larger farmscape scale rather than just a permaculture style small urban or rural garden? I have used it together with biochar in the past with great success on the veggie patch.