Tom has been pestering me for a while to say something about the synthesis of nitrogenous fertiliser using renewable energy. Originally I planned to write several lengthy posts with lots of data and references on this point in particular and on fertilisation in general, but I’m just too darned busy. So here is a briefer and less polished working through some of the issues.
1. Organic Fertility & Its Critics
There’s a wider context here, which is the onslaught against the supposed inefficiency of the organic approach by proponents of so called ‘conventional’ farming on websites such as Biology Fortified, Applied Mythology and SkeptEco. The same onslaught has spawned a thicket of papers and op-eds along the lines of ‘Can organic farming feed the world?’ to which your humble blog editor has, somewhat to his regret, himself contributed. ‘Somewhat to his regret’ because as I understand it around 60% of global nitrogenous fertility comes from organic sources. And we’re asking ‘can organic farming feed the world?’ Shouldn’t we be asking ‘can conventional farming feed the world?’ OK, I accept that organic & conventional farming aren’t entirely reducible to their respective approaches to nitrogen but, c’mon, who’s zoomin who?
Part of the anti-organic onslaught, I suspect, derives from the fact that the presentiments of the organic pioneers about the need to conserve and husband soil organic matter is now confirmed as a rock solid scientific certainty, an ‘inconvenient truth’ for its critics who then feel the need to run organics down in other ways. But I suspect the future shape of farming won’t be determined by partisan opinion-spouters on either side of the organic/‘conventional’ divide. Consider the following statement,
“It is both totally logical and cost-effective to use the resources you already have available in the most efficient way, before you invest in additional inputs…. Soil gradually loses condition, with modern day farming practices requiring it to withstand greater pressures, yet its health is often overlooked, even jeopardised through the use of acidifying fertilisers”1
Who is this outrageous provocateur for the organic way? None other than Hugh Frost, Product and Technical Manager for Mole Valley Farmers, my local agricultural merchants who supply and advise the largely ‘conventional’ farmers in my neck of the woods. It’s interesting to note such comments from a ‘conventional’ farming insider making an implicit ‘organic’ critique of ‘conventional’ practices without the need to mention organic farming at all. So let us be clear – aside perhaps from those benightedly arable-ised regions of the earth intent on mining to death the rich soils bequeathed them by nature, synthetic fertilisers really ought to be a last and not a first resort.
2. Spare the land and spoil the child
Nevertheless, it’s true that per hectare yields of most organic crops grown in present circumstances are lower than those of ‘conventional’ crops. This prompts the so called land sparing-land sharing debate, which essentially boils down to asking whether it’s better to grow intensively with scorched earth ‘conventional’ methods (including more synthetic fertiliser) on a smaller area and leave the rest of creation to the wild things, or to adopt a greater agricultural land-take albeit with organic methods that are hopefully more nature friendly.
To me, this sparing-sharing contrast seems overdrawn, for the following reasons among others:
- we feed vast quantities of our primary arable crops to livestock or to biofuel digesters, and we throw away vast quantities of the rest without eating it (sorry, I don’t have the figures to hand – I’m busy, remember? – but if anyone wants to send some my way, I’d be grateful), so the notion that current agricultural practices ‘spare’ land seems misplaced to me. Why does it make more sense to retain these wasteful practices while slightly reducing the land take with added synthetic fertility than redressing waste and growing organically as much as possible?
- it’s not clear that intensive ‘conventional’ agriculture plus a bit of extra wilderness is in fact more nature-friendly than more extensive organic agriculture, as suggested by ecological matrix arguments or the ‘post-wild world’ views associated with the likes of Emma Marris
- the notion that ‘conventional’ farming outyields organic depends on various implicit assumptions about the conditioning of both ‘conventional’ and organic farming by extant agricultural economics: suppose instead that there were 8 million farmers in the UK, that red diesel cost £10/l and carbon emissions were taxed at £10/kg, then recompute
- looking around my neighbourhood at all the potential sources of organic fertility that go unutilised because the price of labour makes them cost-ineffective, I’d conjecture that if we had those 8 million farmers growing organically, they could easily double the amount of organic fertility available, especially with a bit of smart design on their farms
- evidence that demand for organic produce is driving wilderness destruction is lacking: more plausible candidates are the increasing demand for pork and chicken associated with the growth of the urban middle classes much championed by the eco-panglossians, and more generally the drawdown on natural resources associated with unsustainable economic growth
The last point gives me my title for this sub-section. The eco-panglossians enthuse about getting people out of allegedly ecologically destructive peasant farming and into the cities where they can get an education and become proper, caring environmentalist citizens who pay their annual dues to Greenpeace. I’m sure they’re right that rising Greenpeace subs correlate with urbanisation, but so do all the consumerist behaviours that give Greenpeace its raison d’être. Anyway, more on that another time.
3. There’s more to life than bread and nitrogen
The debate about farmland fertility is heavily focused around nitrogen. That’s fair enough up to a point as it’s a critical plant nutrient, but it’s also just about the easiest one to furnish provided you have enough energy to hand. Maybe some day humanity will be able to take care of nitrogen for good thanks to abundant clean energy and Messrs Haber and Bosch, in which case other plant nutrients that are harder to supply will become limiting factors. That doesn’t mean of course that we shouldn’t aim for renewable nitrogen, but it’s not a case of clean energy + Haber-Bosch = job done in agriculture.
Likewise the debate about agricultural productivity is heavily focused around cereals and grain legumes. Well, we all need our calories and protein and there are a lot of us on the planet. But just as plants need more than nitrogen to be truly healthy, so do people need more than tortillas and beans. Let’s hear it for vegetables, and rein in a bit on the calories per hectare malarkey.
4. Drugs: just say no
Elsewhere I’ve likened fertiliser use to illicit drugs: it gives us a nice quick hit, but with bad long-term consequences for health, if not necessarily for our own health then at least for the health of those anoxic downstream aquatic environments where our fertilisers get flushed, and in relation to associated carbon emissions. That probably goes for all forms of fertiliser, including organic, but especially for cheap and soluble synthetics.
The other parallel is addiction: once you’re on the drugs/fertiliser treadmill you’re buzzing, and it’s hard to get off, as evidenced by the spiralling demand for pork, chicken and other such temptations. There are equity issues here, which I’ll post on soon. But the larger point is can we ever say no, we don’t need more of this, we’ve got enough? I’m not seeing it in the way that the global food system works, just as you don’t tend to find too many abstemious and judiciously indulging crack addicts. If we’re going to ask questions like ‘can organic farming provide enough food for the world’ we first need a proper discussion about how much is enough.
5. Sustainable addiction
But OK, OK. Having said all of the above, I’m not so censorious that I think nobody should ever use any synthetic fertiliser, just as I don’t think it’s always wrong for anybody to take a narcotic hit if they want to. So, if we first attend to endogenous organic fertilisation, diversify our agriculture away from an obsession with economic growth and per hectare productivity of grains, and clean up the way we produce and dispose of nitrogenous fertiliser then, to answer Tom’s question, yes I think there could be a place for synthetic nitrogen fertiliser made with renewable energy on farms.
But I’d like to ask a few questions about what this might involve. Somebody whose chemistry is less rusty than mine may be able to better confirm this line of thought, but my feeling is that nitrogen is the kind of element that likes to play alone. It requires an awful lot of energy to persuade it to come out and play with its hydrogen buddies. And if you’re doing so with renewably generated electricity, my guess is that it would take even more energy than ammonia synthesised from coal or natural gas, because you’d have to work harder to get the hydrogens to play along. The figure in the back of my mind for the energetic cost of modern ammonia synthesis with natural gas is 36 MJkg-1. I’m not sure if that’s per kg of nitrogen or per kg of ammonia (can anyone help?) DEFRA figures suggest that applying 150kg of N per hectare (or even more) is not uncommon for arable crops. So let’s propose a small farm situation in which annually the farmer fertilises one hectare with 150kg of fertiliser at a (very conservatively estimated) 40 MJkg-1. I think that would be a requirement of 150 x 40 = 6000 MJ – which by my calculations is about the amount of fuel energy you’d need to drive an efficient modern car about 3000km (that’s Lands End to John O Groats, back to Lands End then back to John O Groats again before you run out of gas on the fourth leg somewhere in the southern highlands). Quite a lot of energy in other words.
Now, having been living off grid and renewably generating my own electricity with PV panels and a few other gizmos for the past 3 months I’ve developed more than a passing interest in renewable energy performance. We have 12 PV panels rated at 200W (oh, I’m so looking forward to the summer) and a 3000W inverter, which means we can’t really use power hungry things like electric stoves and kettles. Still, we’ve got by pretty well over the winter with a fridge, LED lights, charging laptops, powering drills and angle grinders, and doing the washing on sunny days. For most of the heavy lifting domestic energy usages, however, we’ve burned wood or used bottled gas. Our total electricity use in 3 winter months has been about 200 KWh = 720MJ. So let’s generously estimate an annual usage of 5000MJ – not quite enough to produce our 150kg of fertiliser. And that from an electricity system that costs about £10,000 to install new (though hopefully it’ll last a long time). I guess some of its pricey components like batteries and inverters may not be needed for a fertiliser synthesis system, but presumably there’d be other costly elements in such a system.
Bottom line is I’m not convinced that the best way to go for me in terms of on-farm fertility is to generate electricity and then use it to make fertility. I think electricity is best reserved for the things you really need it for, like computers and power drills, and fertility is best taken care of organically. Doubtless it could be shown that it’s not very efficient producing small amounts of fertiliser using small renewable installations on small farms, and that it’s better to scale up industrially and sell the fertiliser to farmers. But then we’re back in the ‘economies of scale and simplification’ loop that the small farm movement is trying to break out of.
My alternative suggestion is this: develop and incentivise bioregional farming systems that take care of as many of the local population’s needs for agricultural produce as possible using biotic fertility. I think people may be surprised at how much is possible, but also at what has to give and what new thinking is required. If that proves inadequate to your region’s needs, then develop an expensive certification system allowing farmers who fulfil the appropriate criteria and demonstrate their ability to safeguard downstream ecosystems to purchase synthetic fertiliser from renewably-powered industrial units, provided their products are stamped with a label stating ‘Certified Non-Organic’. Data on the proportion of certified non-organic produce consumed in each region would then be collected by national agriculture departments and used in regional sustainability indicators, which could inform economic policies to incentivise reductions in the use of precious electricity to synthesise fertiliser.
Well, it’s a thought.
1. Frost, H. 2014. ‘The soil’s digestive system – improving nutrient uptake’ MVF Newsletter, No.601 June 2014 p18.