WASTE NOT – DUNG AS A HUMAN RESOURCE
HUMANS ARE RESOURCEFUL, adaptable and inventive. Throughout their history, and indeed their prehistory, they have made use of just about every natural product that the planet has to offer. Why should dung have escaped their entrepreneurial gaze? The obvious use for animal dung, and one that is still very familiar to Western readers, is as manure, but before investigating that, it’s worth having a look at some of the other less familiar applications, and also some bizarre tabloid-headline niche uses that have been experimented with down the years.
Perhaps the most sensible of the various alternative uses for dung is burning it for fuel. This really only applies to herbivore dung. As soon as the moisture has left it, the neatly chopped and ground herbage particles, processed and conveniently packaged into briquette- or log-sized parcels, have a consistency ranging from balsa wood to beech logs. I know from personal experience that old horse dung and dried rabbit pellets, crumbling and powdery, make good tinder at the camp fire. In North America, buffalo ‘chips’ were a standard fuel, both for the colonising settlers and for the native first nation peoples. Burned cow pats are still a regular source of domestic heat across much of undeveloped Africa, India and Asia; pats or shaped cakes are dried in the sun, then stacked into architecturally elegant storage piles ready for use.1 From 1870 until 1976 a steamship, the Yavari, plied the Andean Lake Titicaca, its 60-horsepower two-cylinder steam engine famously fuelled by dried llama dung. This is the sort of key fact that tourist guides love to quote, and I can confirm that I am the audience for which such items are intended. If I knew of a dung-powered steam locomotive or river boat nearby, I would have visited by now.
Burned cow dung has also acquired a reputation as an insect repellent, although theoretically any smoke might interfere with the insects’ chemosensory detection of blood-laden humans to bite. Alfred Russel Wallace, co-originator, with Charles Darwin, of the theory of evolution by natural selection (and a personal hero of mine), was more than sorely vexed by mosquitoes throughout his worldwide travels; he was frequently incandescent with rage at them, and wrote about their annoying attentions in many of his books. In September 1849, at Para in northern Brazil, he was being troubled, as usual, by their incessant biting when he tried to write up his diary and scientific notes each evening. To find some solace he copied the locals who burned a brazier of dried dung at every door, it being the only thing that kept the midge plague at bay. He noted that: ‘In the evening every house and cottage has its pan of burning dung, which gives rather an agreeable odour’ (Wallace 1853). It will, perhaps, come as no surprise that experiments to produce insect repellent sprays and oils from cow dung are already underway. It is difficult to know how much credence to give this effort since the dung itself it a powerful attractant of insects, and skatole, the key faecal odour in dung, is also known to be a chemical attractant for some insects including South American orchid bees and various mosquitoes.
In the cool and wet temperate climate of northern Europe, burning dung seems too far-fetched a notion, although there are clear historical records of dung-burning in Brittany up to the beginning of the 20th century. Methane, however, produced by sewage treatment works, and from small-scale manure digesters attached to farms, is increasingly harnessed, stored and burned – a perfectly acceptable modern convenience.
Another intuitively reasonable use of cow dung is as a building material. Mixed with mud, the chewed plant fibres add strength and elasticity to daub applied to wattle walls, or it can be baked into bricks. As soon as it is dry, cow dung loses its smell, all the pungent gases and volatiles have evaporated away, and it becomes a relatively inert substance. Mixing it with clay gives it a rigid strength, and reduces its flammability. This once purely DIY or cottage industry is being increasingly industrialised, and there is usually dung-derived methane available to fuel the brick kilns, giving an extra environmental cachet to the product.
A once widespread practice that has not continued into the modern age is the use of dog dung in the leather tanning industry. This excremental matter was used right up until the early 20th century, collected from the streets where it fell, usually by children, and was part of the noisome substances, including human faeces and urine (collected in communal pots), combined with the smell of rancid fat and decaying flesh, that made tanneries such evil-smelling places, relegated to the outskirts of cities. The dung was used to soften the leather, through the activity of the bacteria in it. Elsewhere pigeon dung was used.2
From these seemingly sensible uses, there now extends a fanciful vista of much odder dung resource possibilities, punctuated with ideas that range from the bizarre to the downright nonsensical. According to tradition, Kumalak, a mystical divination system from Central Asia, relies on a shaman interpreting the patterns exposed when rearranging 41 sheep droppings on a grid of sqaures. Beans or stones can also be used, but since kumalak actually means ‘sheep dung’ in Turkic, I’d feel rather short-changed if it were me having my future read by a proponent using these modern hygienic alternatives.
Dung, as any macerated and mashed plant fibre, can be readily made into paper. Again, once it is dry it loses any faecal scent, but harvesting sufficient quantities has so far kept this a relatively obscure artisan product. Elephant dung is amongst the most inoffensive of droppings, being little more than pre-chewed plant material, passed in large quantity through a digestive tract that works by removing only small amounts of nutrient, but from a vast throughput. Such was the success of elephant dung paper, that similar products are now created from the dung of cows, horses, moose, donkeys and giant pandas.
On the other hand using elephant dung as a textural splatter in paintings, and for the bulky base of designer platform shoes, is simply relying on novelty to gain popular attention. Likewise moose and deer droppings, dried and varnished and made into drop earrings, also rely on a headline-catching you-cannot-be-serious factor.
The latest use of the elephant gastrointestinal tract is to partly digest coffee beans, which can then be extracted from the droppings and used, either to make drinkable coffee (under the brand name black ivory), or to be brewed into elephant dung coffee beer. There is still a bit of the gimmicky sensationalist venture here, but these are genuine and apparently successful enterprises, used to bring in hard cash and garner international awareness in the struggle that is 21st-century elephant conservation. This is still a cottage industry, but it echoes a similar small-scale operation that is now worth tens of millions of dollars. Black ivory takes its inspiration directly from the natural proclivity of the luwak (the Asian palm civet, Paradoxurus hermaphroditus), a small, mostly arboreal cat-like mammal, to eat coffee fruit in its native range across southern and southeast Asia.
The usual history story goes that when the Dutch planters introduced coffee-growing into Sumatra and Java, in the 18th and 19th centuries, they forbade native workers from collecting the fruit from the trees for their own use, such was the high value of the crop. Instead, the local workers collected civet droppings, through which the beans passed almost untouched, cleaned them, roasted and ground them, and made a coffee with an improved aromatic tang and subtle non-bitter taste. It’s the protein content of normal coffee beans which gives the drink its bitterness, and although the nut-hard bean looks unaffected during its pass through the luwak digestive tract, the claim is that these bitter proteins are significantly altered by the enzymes in the animal’s gut, producing a unique smooth mellow flavour. The fame of the kopi luwak (civet coffee) spread and it soon became a marketable commodity in its own right, selling today for something like £500 ($700) per kilogram; forest-collected wild civet-eaten beans are the highest prized, and achieve the best prices. Civet farming now occurs widely in the region, but disreputably poor animal housing conditions, force-feeding horror stories and fraudulent claims of dubious coffee provenance plague the industry.
In yet another variant, caterpillar teas are available in China – brewed from the frass of caterpillars fed on various plants. This is ‘tea’ in the broader medicinal sense of a hot infusion of crushed leaves (or in this case partly digested leaves) taken against complaints of the spleen and stomach, to aid digestion, or to ease summer heat, rather than in the popular milk-and-sugar cuppa beverage more typically drunk in the UK. However, some enterprising wag has taken to offering tea-bags of the stuff for the export market. Unfortunately I just missed a recent tasting in the entomology department of London’s Natural History Museum, where the general consensus was that it tasted a bit like tea.
I am pretty skeptical about the claims of William Salmon, whose book The Compleat English Physician of 1693 gives details of sheep dung tea used to treat smallpox, jaundice and whooping cough. At the time, this extraordinary pharmacopoeia of drugs and concoctions was widely ridiculed for its quackery. However, in a recent Dictionary of Prince Edward Island English (Pratt 1988) sheep dung tea is genuinely reported as a folk remedy given to sick people, along with the supporting claim that this is not a euphemism. I would happily taste kopi luwak, but even I baulk at the idea of sheep dung infusions. The various adulteration of tea and coffee acts (1724, 1730 and 1776) are widely claimed to have been needed because of assertions that ground-up sheep dung was being added to what was then an expensive high-end commodity.
Many would argue that civet coffee, black ivory and caterpillar tea are just riding on the back of their novelty gimmick value; taste tests are notoriously subjective, and people will try anything new, reassuringly expensive and claimed to be exclusive. Similar claims can be levelled against the idea of facial beauty treatments made from nightingale droppings (developed in Japan) and chicken dung (Hippocrates suggested pigeon) used to treat baldness. All rely on the unreliable feedback of desperate, often gullible customers.
Lion dung is marketed for its supposed ability to prevent deer, rabbits, cats or other unwanted animals from coming onto private property. Intuitively this may seem plausible: the rationale is that these annoying pest animals instinctively recognise the smell of a dangerous predator and stay away. The trouble is that lions are not native through most of the Western world, so no instinctive recognition of their smell could have evolved in the local fauna. According to the website of the British Deer Society, lion dung is very smelly (as is that of most carnivores), but ineffective. To my mind, human excrement would seem a more logical choice to deter undesirables in the garden. It also has the added benefit of attracting interesting dung beetles. Try it.
Urine is another important biological product that humans have utilised over the millennia. Apart from its important role in leather tanning, it was also used as a cleaning agent because after a time the urea in it breaks down to form ammonia; this specially aged urine (lant) was also used for wool scouring (washing). Combined with straw it was an early source of saltpetre for gunpowder manufacture. Alchemists tried to distil gold from urine, possibly something to do with the yellow colour of the liquor, and although this was ultimately unsuccessful, it did lead to the discovery of the element phosphorus by Hennig Brand, in Hamburg, around 1669.
There is a long-running debate, now probably relegated to the status of myth, as to whether Indian yellow, a rare pigment used in oil painting in the 18th and 19th centuries, really was made from the urine of Indian cows fed on a diet of mango leaves. The leaves genuinely contain a substance mangiferin, a glucosyl xanthone, which is converted by herbivore digestion to bright yellow xanthenoids similar to euxanthine, the scientific name of the chemical pigment. However, whether this ever happened on any commercial scale is uncertain, mainly because mango leaves are quite poisonous to cattle, and it would have been just as efficacious to extract the colour by the routine treatments of macerating, boiling with chemical additives and then purifying by evaporation. It is quite likely that the urine anecdote was invented (or at least enhanced) by someone wanting to keep the arcane mystery surrounding a lucrative and exotic commodity.
There is, however, no doubt over the origins and utility of dominant-buck or ‘doe-in-oestrus’ urines, which are used sold as scent lures for the US deer-hunting market and are widely available in high-street stores there. And in Sudan, cow urine is used as a hair dye, tinting the local Mundari herdsmen’s normally jet black hair a scorched red colour. Of course, urine is still widely used, diluted with water, as a liquid fertiliser on the allotment, but those tales about using it on sea-urchin spikes or jellyfish stings are all nonsense.
Today we waste millions of tons of our own waste by flushing it away down the toilet. Things were not always so. In the West we now have a tradition of sloshing our excrement off into water, as exemplified by those excellent archaeological sewer remains from Orkney, Crete, Rome and the like, but judging from practices further out across the globe, this is not the only way humans have dealt with faecal disposal.
In 1909 US agronomist Franklin Hiram King toured Japan, Korea and China to examine the permanent agriculture which had been practiced for millennia. In a delightful book Farmers of Forty Centuries, published in 1911, he bemoans the wreckless flush-away attitude of the developed world, and enthuses widely about the ingenuity of these great oriental nations. His book is well illustrated with the vessels in which ordure is collected in each house, and how these are garnered by merchants, and shipped by canal barge to agricultural areas for use as manure. King is singularly impressed by the quantities and financial arrangements involved. In 1908 the International Concessions (commercial trade emissaries) in Shanghai sold to a Chinese contractor for $31,000 in gold the privilege of collecting 78,000 tons of human waste and sending it by a flotilla of boats out into the country to be sold to farmers. Meanwhile, in the same year, nearly 24 million tons of human manure were applied to Japanese fields, an average of 1.75 tons per acre. He goes on to extrapolate how many millions of pounds of nitrogen, potassium and phosphorus are squandered annually in the West. His tone is that of an exasperated campaigner, unable to comprehend the profligacy of his native country, and his sentiments would not be out of place in a modern publication decrying the pollution of the waterways and the obvious benefits of self-recycling organic agriculture.
Despite the obvious antiquity of sewage pipes and drainage ditches, sluices and outfall cloacas, such engineering works have only really been viable in towns and cities. Even here, though, erratic piecemeal development often meant that buildings were erected without such utilities. Elsewhere, and especially in rural areas, the latrine gave way to the earth closet, then to the privy attached to a cesspit. Full (or mostly) mains-sewer connection is a relatively recent occurrence.
There have always been a complete mix of sewage disposal options, and one of these has been bucket collection, sometimes for use as manure. ‘Night soil’, as it was euphemistically termed, was collected at night, and carted off, either for dumping away from the town, or to fertilise agricultural soil by the night soil men, night men, or gong farmers.
That human dung is, or was, used as fertiliser should come as no surprise. Modern farming is still much occupied with using animal manure for this purpose. Every dairy or beef farm, stable, stud or chicken battery will have a dung heap from which material is taken to replenish the soil on which crops or flowers are grown, or animals grazed. At best, this agricultural recycling makes regular use of the various animals’ output, but in towns and cities, away from the everyday rural rituals, and populated mainly by people, the emphasis would have been biased towards the getting-rid-of, rather than the making-good-use-of end of the dung disposal spectrum. Very often getting rid of meant dumping in some out-of-the-way place – the midden. The very word itself is a borrowing from Old Norse myk-dyngja, literally a muck-heap, helpfully brought into English with the Viking invasions of the 8th–11th centuries, and from which we also get the word ‘dung’ itself.
Today, the concept of the village or town midden has rather faded from popular imagination, to be replaced by the municipal recycling centre and the landfill site. These modern phenomena have a certain scent associated with them, and usually the sight of wind-inflated plastic carrier bags caught in nearby hedgerows, but in the days of dung-dumping, they must have been truly overpowering places, and any self-respecting metropolitan governing body would want to have them as far removed from the populace as possible.
Of course, the stuff needed to be moved, just as it still was a hundred years ago in the Far East when F.H. King was extolling the sagacity of the oriental ordurers. Read any gritty historical novel (C.J. Sansom, I’m thinking of you here), and with any luck the author will have inserted graphic details of military latrines, public easements, the jakes or other colourful renderings of medieval toilet facilities. This may be augmented by mentions of shit-ditch lane, dung-carts and the heavy stench of human (and animal) excrement as it is taken off from the metropolis to… somewhere. These are based on actual historical documents, but there is precious little trace of such places today. Old castles still show plenty of built-in garderobes, but these were usually just small niches or cubicles with a seat-hole to take effluent straight out into the moat. What must have been quite some considerable industry of manual faeces removal, human and animal, from towns and cities out into the countryside has left small trace on our lives today.
According to most translations of the Bible, Jerusalem had its own dung-port (Nehemiah 2:13) or dung-gate (Nehemiah 3:13, 14, 31) in the city walls. Whether this was where ordure was removed to be dumped out of sight or composted for later use is not clear. In Chaucer’s Nun’s Priest’s Tale, the body of a murder victim is hidden in a dung cart, on its way out of the city to manure the fields.
FROM DUNG HEAP TO HILL OF BEANS
Whether produced by human ordure, or farm animal excrement, the dunghill or dung heap was a familiar part of any agricultural landscape in the world. Again, there are plenty of biblical, Chaucerian and Shakespearian references – thank heavens for searchable online texts, eh? Although disguised by recent changes in language, midden, dunghill and manure are frequent origins of place names, on both larger and smaller scales. Maxfield, near Eastbourne in Sussex was Mexefeld in the 12th century, meox being old English for dung. Terwick, also in Sussex, was Turdwyk in 1291, and is from Old English tord (turd) and wic (farm). In 14th-century Bedfordshire, le Shithepes, is pretty self-explanatory, similarly Sithepes in Cambridgeshire. Middyngstede in Yorkshire (1548) and Myddenhall in Dorset (15th century) are just two of many places named after the midden. Closer examination of old documents and maps shows that there was a whole slew of field names, obviously connected to manure heaps and the regular manuring of agricultural land (Cullen and Jones 2012).
Today, manure heaps, dung piles and slurry pits continue to be a managed part of modern animal husbandry. As well as getting the smelly and sloppy contents of the stables and cowsheds out of the way of the housed animals, the mounds of composting material are available to the farmer when it is muck-spreading time in the fields, though human faeces no longer feature heavily in this process in developed countries. Having said this, in my 1930, 11th edition, 45th thousand printing of Primrose McConnell’s famous Agricultural Note-Book (first published 1883) human ‘egesta’ is listed in the tables to help calculate the spreading rates, and the nitrogen, phosphorus and potassium contents of various manures, along with night soil, both solid and liquid combined, and dried, also town sewage and dried sludge. Presumably McConnell was addressing the sewage farmers as well as the traditional farmers with his popular publication.
Although almost all types of animal dropping can be used in spreading manures, cow dung is the default option across most agriculture, at least in the UK. Produced in copious quantities in the farmyard and milking pens, its semi-liquid nature (77–85% water) means that it can be eased by gravity, and a person pushing a shovel or broom, into slurry tanks or what is sometimes optimistically called a lagoon. Here it can sit, gently fermenting for a few days, before it is pumped out into tankers, muck-spreaders, sprayers or whatever device the farmer is using to apply it to the fields. As I sit and write this in London, in April 2015, my 10-year-old son is getting ready for a week-long school trip to a farm in Devon. He knows what to expect, having heard it from his two sisters who also went there. Despite the bottle-feeding of cute baby lambs, feeding the pigs and chickens, collecting eggs, milking the cows, and going for bracing country walks, the single most powerful memory all the primary school children come back with from the farm is the orchestrated shovelling of cow poo across the yard – the runniness of the stuff, the high smell of it all, and who slipped over in it. This is the stuff of schoolchild legend.
Pig dung, at 72–75% water is also relatively manoeuvrable from the farm yard or sty, but more powerfully pungent, unless the animals are fed on Jerusalem artichokes perhaps.
Horse manure is the favoured dressing and soil nutrient for allotment gardens and smallholdings, and continues to be offered virtually free to passing gardeners by stables up and down the country. Its relative dryness and inoffensive fruity smell make it easy to cart off in the car in plastic bags. Some years ago, when we lived in Nunhead, one of my neighbours was bemused to see me scoop up for the garden the deposits left by two police horses that had recently passed down the street. Well-rotted horse manure is also a popular substrate choice for mushroom growers.
Battery chicken houses produce tons of chicken droppings, which are collected, pelleted and sold for domestic fertiliser. Because faeces and urine are expelled together in a single dropping via the cloaca, as all birds do, chicken manure contains very high levels of phosphate, nitrate and potassium, key nutrients for plant growth.
Manuring was especially important on ‘poor’ soils. The chalk downs, limestone hills and rocky uplands of the UK sometimes have only a few centimetres of topsoil, low in nutrients and easily lost to wind and rain when ploughed. Sheep-grazing was the only possibility on some of the steeper slopes (it still is), but this fitted into a neat regime to bolster the fertility of the more gentle slopes where arable crops could sometimes be grown. During the day the sheep were free-roaming on the steeper hillsides, under the watchful eye of the shepherd, but at night they were dog-driven then penned in fallow fields nearby where their droppings would fertilise the soil for the crops grown during the next cycle. Such was the importance of sheep on the chalk hills of southern England, not just for wool and meat, but as mobile manure carriers, that they were similarly day-grazed on rich water-meadow grass in early spring and again folded on the fallow chalk land at night. In the mid-19th century sheep were increasingly given oilcake feed (from the waste residue of crushed oilseeds), not just to improve their mutton output, but because the cake paid for itself in the superior manure that they produced on cereal-growing fields (Bowie 1987).
Today the value of the world manure market can only be guessed at. Figures reaching scores or hundreds of billions of US dollars are regularly bandied about. Such is the international scale of the manure trade that governments have legislated on it and wars have been fought over it. In 1856, the USA passed the Guano Islands Act, by which US citizens were empowered to take possession of any unoccupied guano islands they encountered in their travels, and over which the US would then offer military force should these interests need protecting. The ‘Guano War’, more precisely the Chincha Islands War (1864–1866) began when Spain seized these guano-rich islands just off the Peruvian coast, much to the displeasure of Peru and Chile. The War of the Pacific (1879–1883) between Bolivia, Chile and Peru was sparked by disputes over boundaries in the Atacama Desert, where significant quantities of guano had been discovered.
Guano, from the indigenous South American Quencha word wanu (or huanu), comprises accumulated deposits of bird excrement, mainly from the guanay cormorant, Phalacrocorax bougainvillii. The extremely dry climate of western South America, in the rain shadow of the Andes, allowed the droppings to amass over millennia, neither decaying, nor being recycled by natural processes, nor being leached by rain, and deposits achieve depths of 50 m. Guano is easily mined and transported, and since it is dry and relatively odour-free it makes an easy and convenient fertilizer high in nitrogen (usually as ammonium salts), phosphorus and potassium. Guano remained a primary source of agricultural fertiliser until the early 20th century; in 1869 over 550,000 tonnes were mined. In Peruvian history, the period 1845–1866 is referred to as the ‘Guano Era’. It was only eclipsed when the Haber–Bosch process was able to make ammonia from atmospheric nitrogen on an industrial scale using a high-pressure furnace and beds of metal catalysts. Guano is still mined and marketed as fertiliser today, but on a much smaller scale.
Of course, all of these commercialised and targeted manure and guano possibilities hinge on there being animals contained in barn, sty, shed, coop or stable, or age-long accretions of natural droppings, from which the biological matter can be cleared and piled up, packaged, transported and stored ready for use. Out in the field or meadow or wood where free-range animals roam, the dung lays where it is dropped. The soil will eventually get the benefit of the recycled fertilising nutrients, but first the dung attracts the attention of other users.
1 These cakes (called gobar upla in Hindi) are widely available on Indian mail-order websites, but for ritual or nostalgic burning by urban dwellers, far removed from the cows of their childhood, rather than domestic heat production.
2 Incidentally, the oft-quoted eating of dove’s dung in the Bible (2 Kings 6:25), costing five pieces of silver for a quarter cab (about 300 ml), most likely refers to an as-yet unidentified plant then given that idiomatic name because of some supposed resemblance to pigeon droppings.