Some further thoughts on organic fertility

I’m going to continue my theme from my last post about organic fertility in future farming, picking up on a few of the very interesting comments that people made in response to it. Apologies that it’s taken me a while to get around to this follow up post – work just keeps finding me. In fact, I’m going to keep this briefer than originally planned so as to keep my head above the water.

Anyway, many thanks for the comments. For the most part, I’m not going to respond to named individuals, instead focusing on the general issues people raised. I’m going to do it in the form of a set of numbered propositions that hopefully will clarify my position, and perhaps also act as a spur to further discussion. A lot of the comments focused in one way or another around the framing of my post, so I’ll begin with that.

  1. The title of my previous post – ‘Can organic farming feed the world?’ – was probably a poor choice and arguably falls into a Lakoff framing trap, with its underlying implication that non-organic (‘conventional’, ‘industrial’ or synthetic nitrogen) farming faces no parallel question. For my part, I do not assume that non-organic farming as it’s generally practiced at present will be able to continue to feed the world (in fact, I strongly suspect it won’t be able to). All the same, I think it’s legitimate to ask the same question of organic farming, and follow through on the implications.


  1. The structure of my post followed David Connor’s paper, which looked top-down globally at the amount of biological (‘organic’) nitrogen fixation (BNF) and the amount of synthetic (‘non-organic’/‘industrial’) nitrogen fixation (SNF). An alternative approach is to look bottom-up locally – how much land and other resources do I need to provision myself without SNF in the place/region/country where I live? This latter approach is precisely the one I took in Chapter 11 of my book A Small Farm Future for the case of the UK – and the answers I came up with is ‘not very much’ and ‘yes, we can easily provision ourselves using only BNF’. But you have to make a lot of detailed assumptions to undertake the bottom-up approach, which are difficult enough for a single country or bioregion, let alone for the whole world. So there’s something to be said for looking top-down globally as a complementary approach, starting from the reality of how much BNF and SNF there actually is in the present world.


  1. Still, the problem with this top-down, status quo approach is that it often mistakes the way things are for the way they should or must be. I like to think that my previous post gently undermines such assumptions in Connor’s paper. We don’t need to devote cropland to livestock production. We can devote more labour to global agriculture than we presently do. We don’t need to waste so much food. And so on. In this way, I think we move the debate more towards the bottom-up approach. Can we get by globally with only BNF? Probably yes, just about, if we change some of our framing assumptions about how we do agriculture globally.


  1. But why does it matter whether we can get by with only BNF? In the world as it presently is, at the level of the individual farm, my answer is – it doesn’t. Indeed there may sometimes be a case for using SNF and, at the farmer-to-farmer level, I concede there’s much to be said for avoiding a polarized SNF versus BNF debate (with the proviso that this onus also falls on pro-SNF, anti-organic advocates like Connor). However, I think it does matter at the level of the total farm system, because SNF requires highly complex industrial infrastructure, and it readily enables farmers to engage in non-resilient and unsustainable cycles of productivity gain. I don’t think we can build congenial and renewable cultures long-term on this basis. So if it turns out we can’t feed ourselves without SNF, then we’re in quite a predicament. Happily, that doesn’t really seem to be the case. Suggesting how that may be so was the main point of my previous post.


  1. There are different ways to increase productivity in agriculture, of which N fixation methods are only one. Another is devoting more human labour to smaller, more intensively worked holdings and farmscapes. I don’t think it’s possible to overstate the importance of this more labour-intensive approach for a renewable human future – it’s central to my book, and to this blog. Implicitly, though, more labour-intensive farming probably means more BNF. It certainly means more careful N cycling.


  1. Underlying the N debate is another one about the place of livestock in our farming and of meat in our diets. I’m not going to wade too deeply into that here, although I’m aiming to devote a future post to it (see also Chapter 8 of A Small Farm Future). Commenters on my previous post touched on the issue of using soy to manufacture ‘fake meat’ more efficiently than of using it to feed livestock that are slaughtered for meat. Again, I see this as a present vs future food system issue. In present circumstances, maybe there’s something to be said for favouring ‘fake meat’ over actual meat. In future circumstances, there will be something to be said for a world of smallholdings and agricultural commons where livestock are kept primarily to improve the efficiency of tapping and cycling nutrients in low energy farming systems. Either way, we will be producing a lot less ‘real’ meat for human consumption (though its consumption across the population may be better distributed).


  1. Thinking in terms of BNF and SNF rather than organic/conventional farming is useful to avoid missing the various ways in which N from SNF finds its way into organic farming or gardening, which people then too easily assume derives from BNF. This is probably even more important when it comes to phosphate rather than N. The study cited by Shaun Warkentin suggests that around 70% of P inputs in a sample of organic farms in France came from conventional sources, and the main conventional source for P is unsustainable mining. Ultimately, the long-term necessity to cycle rather than mine P could be a key factor propelling humanity back to a predominantly rural, distributed and agrarian human geography.


  1. The excellent possibilities for BNF and for P cycling in small-scale paddy rice farming systems suggest they are a renewable farming approach of choice for the future where they’re feasible. The methanogenic nature of paddy farming (and of smallholder livestock keeping) is irrelevant to its long-term sustainability, whereas short-term elimination of fossil fuel combustion is critical. Economic development policies should support small-scale paddy farming and avoid explicit or implicit fossil fuel dependence.


  1. With characteristically effective sleuthing, Steve L has uncovered the figure of 28 Mt of fertilizer lost annually in the food supply chain. With this corrected for, the need for SNF potentially shrinks to near zero – but I’m not sure how much N there is in this 28 Mt, so I’ll leave that tantalizing prospect hanging for now.

27 thoughts on “Some further thoughts on organic fertility

  1. I’ll say it again: modern cities can only exist becaused they are supported by industrial agriculture. Industrial agriculture can be based on BNF or SNF. I think that BNF could entirely substitute for SNF in industrial agriculture if different foods were grown and those foods were distributed differently, but that would not save modern cities, and the advantage of BNF would be minor and short lived.

    Industrial agriculture is not sustainable regardless of the source of N. Modern cities are therefore not sustainable. When they fail and most people live an agrarian life, BNF will supply the only N available and it will support people (the survivors) just fine. But if someone wanted to gift every small farmer a temporary supply of synthetic N somehow, those small farmers needn’t turn it down. They should use it well as long as it lasts. The same might be said for diesel fuel and farm machinery.

    In the long term, a renewable source of energy for farming is far more important that the source of N. Hence, your sentence, “I don’t think it’s possible to overstate the importance of this more labour-intensive approach for a renewable human future” sums up farm energy supply priorities perfectly. But then, I’m already a longstanding member of the back-to-the-land choir.

    Get people living on small farms any which way we can. Their interim farming techniques could vary wildly, but will rapidly sort themselves out to optimize whatever resources are available. Eventually, those techniques will all be based on muscle power and BNF. That much is certain.

    • Certainly in the UK, and most centrally in England, issues of land ownership and planning restrictions require resolution before the creation of new small farms is a widespread possibility. Even in Wales, where for a decade new small farms have been possible under the One Planet Development scheme, the total area of such farms, about four dozen in all, is probably no more than 500 – 600 acres.

      • I strongly agree that issues of land ownership and planning restrictions require resolution before the creation of new small farms is a widespread possibility.

        The One Planet Development scheme in Wales sounds interesting, but it “does not really allow for the recreation of a rounded rural economy,” according to this fellow who went through the process:

        “There has been just criticism of the OPD policy by, amongst others, Simon Fairlie. It has been pointed out that really OPD offers no more than temporary planning permission; it recycles the old financial test, albeit at a less demanding level; there are certainly problems reconciling OPD-type housing with building regulations created for mainstream construction. Most seriously of all perhaps, OPD fails to offer people who do not want to, or cannot, establish land-based businesses, a way to apply for greenfield planning permission.”

      • Too bad the sewage sludge had to be shipped in the first place, but since it’s in Alabama, perhaps some of the numerous forestry outfits there could either apply it to their tree plantations as, has been done near Seattle, or mix it with wood chips and compost it (plenty of wood for composting in New York, too).

        Another good alternative is discussed here:

        But one of the problems of nutrient cycling from cities is toxic waste entering the nutrient cycle from factories. Both fish farms and compost production can be harmed by some factory effluents.

  2. The meat thing is interesting. I thought my household ate a lot of meat (I tried vegetarianism, or nearly-vegetarianism anyway, for over a decade and felt hungry the entire time no matter what I ate, and I certainly enjoy eating meat), but we recently subscribed to a monthly meat delivery box supporting a mostly-pasture small farm, and… we (3 adults) can barely keep up with it. Partly this is because we actually eat less meat than I tend to think we do; partly it’s because the meat we do get in the box is incredibly filling. If we have supermarket sausages for sausage sandwiches or sausages and mash I’ll easily eat four or five sausages; the mostly-pasture ones are about the same size, but I struggle to manage two. I don’t think it’s only about the protein content, because the same dynamic also seems to apply to roasts and mince: we’ll get three meals rather than two out of a roast, and two rather than one out of a packet of mince.

    Just an n=1 of course. But there does seem to be a difference between grades of “real” meat, and I’m a lot more comfortable with the idea of eating less meat if the quality is this good and I know I’m not being asked to endure the constant hunger I felt in my nearly-vegetarian years.

    (The subscription box thing is a whole other kettle of fish, but it’s the sort of box where the supplier decides what to fill it with, so they have some security of income, and as we are currently stuck in London and not going to start rearing pigs or grazing sheep in our rented back garden anytime soon, it seems like a good compromise.)

  3. Pingback: Some further thoughts on organic fertility | Small Farm Future

  4. Regenerative farming can eliminate the need for fertilizers either organic or synthetic. On our regenerative grain farm, there is no longer a yield drag, we are able to feed just as many people under regenerative practices as we did using conventional farming methods: but our inputs have decreased dramatically and the grain quality under a regenerative system is far superior. Let me explain. Our regen system uses a NO-Till model 1st and for most. Tillage is the most devistating “tool” in a farmers tool box. Tillage destroys the soil microbiome connections in the soil. The seeds, roots and plants rely on this microbiome to form connections that will allow these plants to be nourished by the microbes and minerals already present in the soil( i could go on and on). Because we dont use any form of fertilizers, our plant roots are forced to work within the soil microbiome to nourish themselves(and they do) we dont use any pesticides or fungicides. We also incorporate multispecies cover crops to feed the soil through root mass inbetween cash crops. All of these practices lead to more nutrients being available in the grain we grow. Better for human health AND better for the planet

  5. but I’m not sure how much N there is in this 28 Mt, so I’ll leave that tantalizing prospect hanging for now.

    A wise choice. N fertilizers come in many different forms and thus also in many different concentrations. N can be a component of some P fertilizers, as well as strictly N types (eg., urea, ammonia (NH3), and at least a couple ammonium nitrate liquids and a solid ammonium nitrate type). The amount of N per pound is different in all of these.

    But I’m not certain we need to determine the exact amount of N in the cited 28Mt… their point is by reducing significant levels of food waste we also reduce the need for attendant resources necessary to produce the food in the first place. The efficiency of food production varies all across the planet. Indeed this wide variation in efficiency of production is likely to persist far into the future regardless of farm size and/or the amount of close on human labor dedicated to the effort.

    For me, the secret sauce of a small farm vision is the immediate proximity of end users to the source of their nutrition. In a good year you can be a bit choosy, and even a bit less careful. In a challenging season you are likely to eat whatever presents… and to be far more careful managing resources. In order to have such simplistic approaches however will necessitate having a broad ranging infrastructure both locally and globally (infrastructure such as adapted germplasm, preservation techniques, access to locally relevant knowledge, disease prevention and treatment, etc).

    To Joe’s frequent appeal that folks too far removed from food production (city dwellers) start looking toward their future sources of nutrition – I have to wholeheartedly agree.

  6. Organic fertility- While Nitrogen is an essential nutrient, one should keep in mind Liebig’s law, both at the garden or field level and system wide. I recently had a soil test done, and the land we are restoring ( had been being hayed for years without inputs) was low in sulphur, calcium, potash and phosphorus. I spread fertilizer this spring (organically certified) but who knows where it came from. I’m in repair mode, but not sure what the path is to zero inputs. Even rotational grazing and perennial plant based foods will exact a cost unless we do full recycling. If we continue to obtain a yield and don’t return every single component back to which it was drawn, it is not sustainable.

    System wide (global) fertility and ability to feed all is only relevant if energy is available to transport inputs long distances from source to field and food from field to city or to another country. In this case, I would say energy is the limiting factor and as much a question as nitrogen, and shifts the question of organic versus conventional to one of local versus industrial/global.

    As far as the misleading choice of organic versus conventional ag feeding the world, as I commented on last post, the framing is being ceded, and needs to be challenged. How does conventional ag propose to continue when the phosphorus mines have played out and there is not enough energy to continue Haber-Bosch NH3 from natural gas? How much further can the can be kicked?

    The long term goal of necessity is to fashion food systems that matches the local carrying capacity. Populations will shift and decline to this arrangement, and there is really no other choice. A small farm future heads us toward this goal.

  7. Thanks for the comments. Much to agree with in them. A few points.

    Little to dispute with what Joe and Steve C say. I think I’ve said above what I wanted to say about issue-framing. Agreed that the days of the urban/industrial-ag complex are numbered, for reasons largely unconnected with N fixation. But that’s not the same as saying that the matter of biological N fixation in a more renewable agriculture is of no interest, right?

    To Calon Cymru Network & Steve L, indeed landownership and planning issues are key to any possibility for a small farm future in the UK and many other places. I address this in Part III of the book, and will be coming on to it here on the blog soon. The piece Steve links to about OPD in Wales gives a good sense of the forces ranged against creating renewable rural culture presently in the UK. All I’ll say is that if the situation in Wales with OPD sounds bad, England is considerably worse!

    Interesting comments on meat, Kathryn – again a topic that I’ll be discussing soon. Your approach makes sense in your situation, I think. Generally I try to eat only meat from livestock that we’ve raised ourselves on the holding, amounting to about one or two meaty meals per week. Can’t say I’ve experienced the same self-limiting experience with well-raised meat as you, but then I’m quite carnivorous by nature and very much identify with Jack Sprat’s wife All the same, I probably wouldn’t like to eat a much meatier diet now I’m habituated.

    DeAnna – likewise on regen ag, I’ll be commenting briefly in my next post. I’d be interested in other views, but while I could probably be persuaded that global ag can make do with BNF from soil bacteria alone if somebody showed me their figures, I’m unpersuaded that it can renewably supply most of the other necessary plant nutrients from the soil – most notably P – without soil mining, unless it’s re-importing those nutrients somehow. As I see it, this is definitely a time to be experimenting with the kind of techniques you mention, but the jury will be out for quite some time to come.

    And to close, a nicely turned phrase from Clem – “the secret sauce of a small farm vision is the immediate proximity of end users to the source of their nutrition”. I think this is a profoundly important point, and I’ve been making it in various presentations recently … often to a blank incomprehension that reinforces for me how deep in the mire our culture really is…

    • the immediate proximity of end users to the source of their nutrition … is a profoundly important point, [which is often received with] blank incomprehension

      That’s intereresting, because it seems self-evident to me (though I’ve met blank incomprehension in relation to other sustainability issues). So now I know that it needs to be actively explained.

      Perhaps the reason for the incomprehension is that the imperative to ‘eat local’, (as opposed to ‘eat from anywhere’) implies that not all trade is good. And that idea has become almost unthinkable?

      • Trade that is essential for life just has to be good, n’est ce pas?

        It’s going to be a hard sell, telling people that they have to radically change their entire lives just so that they can avoid being dependent on long distance trade, something that has been a reliable part of their lives forever. It would be like telling them they should avoid being dependent on money, something that is almost incomprehensible to people immersed in a market economy. Fish/water.

        I think that it’s going to take empty store shelves or empty wallets to convince most people that something is amiss with a globalized industrial civilization and that they need to consider alternatives. Of course, by then, the alternatives will be even more out of reach than they are now.

      • Indeed, I think the notion that all trade is intrinsically good lurks behind a good deal of the mutual incomprehension. As I see it, trade is good when it’s supported by everyone who’s affected by it – and that means everyone has to have the choice of not trading, and of insulating themselves from the effects of other people’s trade. To do that, they need to have the means of producing the necessities of life for themselves. A small farm, in other words…

  8. We might be leaving out all the work Nature does. In New Mexico we have enacted a healthy soil act. We even appropriated money, difficult in poor NM, for projects to assist landowners to improve their soil. Through five principals:

    Keeping the soil covered;
    Minimizing external inputs and minimizing soil disturbance on cropland;
    Maximizing biodiversity;
    Maintaining a living root;
    Integrating animals into land management. (Which includes earthworms)

    Practicing these allows soil life to make soil more friable and welcoming to plants. N fixing organisms can provide all the N needed, plus up the general fertility. So total N is not finite. Of course, this requires the farmer’s most important quality, patience. Inevitably, we will probably have to depend solely on Nature to feed ourselves. Utilizing fossil fuels might become a capital offense.
    Although this is a belief system, one must believe in things if one is to farm.
    I have a blog on our website titled A Small Farm Future. Sorry for all the thievery.

    • Hi Lynn, thanks for that. Yes I agree that for agricultural purposes total N is not finite. But there are nevertheless tradeoffs between N capture, work/energy input and yield, which are finite. When it comes to most of the other plant nutrients, however, they are finite, because they don’t cycle in the way that N, C and O do. So there’s potentially a long-term problem there unless you’re returning them to the soil. But I agree that farmers need to believe in things, and to experiment. We just need to be aware that the experiments are necessarily long term.

  9. On nutrients I think we need to look into a mix of:
    1. Using biological nitrogen fixation. Here I believe the potential of free-living nitrogen fixing bacteria has got far too little attention.
    2. Close nutrient cycles as much as possible, including but not limited to recycling of all sorts of “waste” in the food system (also humanure), plugging all leaks (by means of avoiding bare soil, overirrigation etc)
    3. Stimulate soil microlife which can activate a lot of existing minerals. In many soils the stocks of e.g. P is very big, but it is not available to plants, that is also the case in many tropical soils as well as in my own soil. Mykkorhiza (a word what is always difficult to spell) can play a very big role here.
    4. Grow the soil: Soil is not static but can grow upwards and deeper, apart from becoming richer. Deep rooted plants can increase the depth of soils considerably as well as feeding a microlifte deeper down.
    5. Import nutrients from other eco-systems: This has been a component of most agriculture system and is done in many different ways. Fisheries and other kind of sea or lake harvesting bring in “new” nutrients in the food chain regardless if it is eaten directly by humans, by livestock or used as fertilizers. There are plenty of lakes and coastal waters that are contaminated by too much nutrients, mostly run off from agriculture or other pollution. One can bring those nutrients back to land. Grazing animals on permanent pastures also bring in nutrients to the system either from manure collected or through the products entering the food chain – mostly both.
    6. Integrating livestock and crops in the same farm will reduce wastage compared to concentration of livestock in big units.
    7. Reducing food waste and efficient handling of the waste.
    8. (Limited) use of mined natural minerals. Only in Sweden we have huge deposites of P-rich apatite and K-rick biotite which are rest product from mining.
    9. Selecting crops and rotations better adapted to the local conditions.
    Still, nutrient supply will always be a challenge for farmers.

  10. Hi Chris. Interesting post, yet again. Have you ever heard of the idea that the main limiting input in agro-ecosystems is not Nitrogen or Phosphorus or any of the other commonly mentioned nutrients, but Carbon? Carbon provides the energy the soil micro-organisms need to mobilise the other nutrients: The energy to fix atmospheric nitrogen, the energy to mine locked-up phosphorus, etc. I first came across this re-framing while watching some lectures by Konrad Schreiber for the Maraichage sur Sol Vivant network in France. It struck me as quite insightful on many levels.
    He then used it to calculate the annual biomass (straw/hay/woodchip/cover crop…) applications necessary to “fertilise” a field with carbon and then had a long discussion on how to grow that biomass in the first place in different growing systems. In his framing, legumes do not provide nitrogen to the soil, it’s rather that they are able to grow lots of biomass in low-nitrogen conditions… Subtly different.
    Unfortunately for non-francophones, the lectures are all in French. I’ll post the link here anyway:

  11. Thanks for the phosphate links Gunnar & Clem, and for that very lucid exposition of the regen ag argument Joshua. It’s all quite relevant to my next post, so I’ll aim to come back to it shortly 🙂

  12. Along these lines, Kris De Decker over at Low Tech Magazine recently posted a good article on fish pond sewage treatment for cities/urban areas.

  13. What we are up against . ( worth a read and chasing the links

    Smallholder peasant farming is to be eradicated as the big-tech giants and agribusiness impose lab-grown food, GM seeds, genetically engineered soil microbes, data harvesting tools and drones and other ‘disruptive’ technologies.

    We could see farmerless industrial-scale farms being manned by driverless machines, monitored by drones and doused with chemicals to produce commodity crops from patented GM seeds for industrial ‘biomatter’ to be processed and constituted into something resembling food.

    • We could… though we could also see many other futures.

      To suggest big-tech giants and agribusiness will “impose” anything is to misunderstand our present market system. There are currents in marketing systems that may eventually give the richest capital holders the agency to “impose”, but for now the opportunity to push back, or to compete still exists. Letting the moment pass – to miss the opportunity to affect future directions – would reflect as poorly on the rest of us as it might on the monopolists and the rest of the “BIG” entities.

      Lab grown food for instance. There are arguments for adoption of this technology, just as there are arguments against it. An opponent of LGF should have no more right to “impose” her will against it than the proponent “impose” hers for it. Give consumers choice.

      Of the currents that might allow even greater agency to the already rich and powerful (alluded to above) – surveillance capitalism stands at the front of the line IMHO. Going offline seems to me the easiest way to counter that threat. A small farm future could be just the ticket – the push back if you will. But at the same time, there shouldn’t be any effort to “impose” such a future on those not ready or willing to participate. Environmental conditions may force matters – may “impose” alternative realities. We can prepare, and we can remain vigilant. But so long as we can grow our own food (and opt out of a BIG food future) then no one can “impose” upon us what we will choose to eat.

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