The Vital Cycle
Global nutrients, household opportunity
Global nutrients, household opportunity
The Earth’s biosphere is constantly cycling through material in a complex network of energy and matter. It cycles not just through the bio-massive bulk, but also through the more ecologically valuable nutrients. Soil fertility is the vitality of the planet, and the source of our fuel and substance as living beings. As human individuals, we are part of that cycle and so too are we as societies. Like our heartbeat, respiration and immune system, the flow of biomass and nutrients on Earth is vital to health and happiness. But these cycles are falling sick and we ignore the disruption at our own peril.
There is a medicine available, however, and the secret ingredients are surprising in their simplicity and abundance: food scraps, rotting plants and animal excretions. This medicine is known as composting and it is a remarkably simple skill to learn. If everyone were able to effectively compost their own organic scraps, the world would be a better place.
Our ancestors would be amazed at the waste of organic material in our cities. Without giving it a second thought, we send this valuable material to the landfill or downstream to the ocean, but we truly need to learn to reintegrate this precious rubbish back into the ecosystem. While the abundant quantity of biomass is an important cycle of reintegration, it is the quality that is so vital: nutrients. The humble sounding compost bin is one of the keys to a healthier environmental future, allowing us to recycle the nutrients that we consume or waste.
It can be as simple as a bucket kept by the kitchen tap, or as complex as an industrial facility recycling a city’s garden waste and human sewage.
Nutrition and nitrogen
Plants, and by extension virtually every other terrestrial organisms, require a mix of elements to survive. Besides carbon, which provides the chemical lattice for biological molecules, the elements of nitrogen, potassium and phosphorous are essential nutrients. Other elements are required: calcium, sulphur, magnesium and, to a lesser extent, 10 other trace elements such as copper, selenium and iron. Nitrogen is especially important and is incorporated into the genetic material of every cell. Biological information, DNA, is written with molecules incorporating nitrogen. Until very recently, nitrogen was the limiting nutrient in human agriculture.
The atmosphere contains abundant nitrogen – in paired atoms, as N2 – which is biologically elusive. Although we inhale this gas with each breath, it is impossible for most organisms to chemically exploit it. Some groups of ecologically critical bacteria associated with certain groups of plants, such as peas and alders, can “fix” nitrogen from the atmosphere; this is Nature’s way of providing this element to the ecosystem. There is also a trace amount of nitrogen fixed by the energy of lightning strikes.
Ancient agriculturists returned the valuable nutrition on a large scale, by fertilising fields with animal and human manures, and on a small scale, by throwing food scraps and yard clippings into kitchen gardens. These skills still exist, but most farmers have taken advantage of modern fertilisers to dramatically increase crop yields. The overabundance of food that we enjoy in the modern day is a recent blessing. But there is a darker side to this bounty: dependence on fossil fuels,
irrevocable alteration of the geochemical cycle and the ongoing abandonment of sustainable agricultural practices.
Altering the cycle
In the first decade of the 20th century, a German chemist named Fritz Haber led a team of scientists that truly altered the biogeochemical cycle of Earth. Using newly developed high-pressure equipment and improving on an inefficient Norwegian process, they discovered a cheap method to create biologically useful ammonia (NH3), which could then be used to produce ammonium nitrate. The ammonia molecules are created from a combination of atmospheric nitrogen (N2) and hydrogen gas (H2) from methane fossil fuels. Nitrates are excellent soil fertilisers, and they had never been available in large quantities. Previously, the major sources were Chilean desert salts, underground accumulations of bat droppings and aboveground accumulations of bird droppings.
Tragically, this process also opened the doorway for industrial manufacturing of gunpowder and explosives, a key secret weapon of the German war machine. (Ammonium nitrate can also be used as an oxidising agent in explosives.) Haber himself, born Jewish, was a prominent developer of the German chemical weapons arsenal in the First World War and his deadly gases would later be used in the Nazi death camps to exterminate the Jews of his beloved country. He would end his life in exile.
Just as significantly, the Haber Process is one of the main chemical processes responsible for the artificial increase in soil fertility around the world. Ancient practices of recycling nutrition via compost and manure have been abandoned in favour of manufactured fertiliser containing nitrogen and other chemicals. The food you eat, and the cells in your body, incorporate vast quantities of Haber-processed nitrogen. At least a third of the human population on Earth exists as a
“Ancient practices of recycling nutrition via compost and manure have been abandoned in favour of manufactured fertiliser containing nitrogen and other chemicals ”
direct result of this process – before Haber’s work, there was simply not enough soil fertility for agriculture to support so many people.
Fixing the cycle
We are now in a delicate and unsustainable situation. A substantial portion of Earth’s energy is diverted to producing nitrates and its overabundance has altered terrestrial and oceanic ecosystems. The amazing growth rates of artificially fertilised agricultural plants strip the soil of other nutrients, as they are repeatedly harvested and shipped away. Excess nitrogen flows downstream from farm fields to the ocean, killing the biota and encouraging toxic abundances of microorganisms.
Similar stories could be told regarding the industrial manufacture of other elemental nutrients. While they have created great bounty, they are also an addiction for our species. At a large scale, it is unclear what options the future holds for agricultural fertilisation. While creating industrial fertiliser is an obvious priority for fossil fuel usage, the question of alternative energy sources remains unanswered. With human populations still growing, we will become more and more dependent on these industrial techniques. Clearly, reducing our reliance on artificial fertilisers is the path of wisdom.
The large scale: Sustainable agriculture
It is in the best interest of the individual farmer to have high yields, but it is in the best interests of humanity as a whole to have sustainable practices. A more calibrated use of industrial fertilisers could reduce the toxic effects of runoff and help to keep our waterways and soils healthy. Farm waste such as cornhusks, root vegetable stems and cereal stems can all be recycled into the system. Large-scale processing of human and farm animal sewage into safe fertilisers would contribute greatly to future sustainability, but this requires highly organised efforts. Indeed, many sewage treatment facilities are working to create agricultural fertilisers to be used on forestry and farming lands.
Private enterprises now harvest municipal discarded green waste – especially from urban parks and lawns – and sell this recovered material at a profit for use in landscaping and agriculture. These businesses can operate efficiently at large scales and with specialised expertise. But what about at the small scale?
The small scale: Urban composting
Imagine the preparation of a large meal and the dynamics of a kitchen. With sharp blades and other tools, we discard the seeds of one vegetable, the skin of another and the bones, organs and skins of animals. Whether you eat from a private kitchen or from a restaurant, there is a substantial amount of discarded food that is inedible or unpalatable to us, but is full of vitality and nutrition for plants. In some cities, you can have this waste collected for
“In all nations, no matter the level of urban development or the type of diet, we depend on the soil fertility for life”
municipal composting, or you can deliver it to a collection point. But why not keep the cycle close at hand?
First, you will need a destination for the compost. You can create a small kitchen garden in pots on a balcony, or in any abandoned urban green space. From this garden, you can create a supply of food that will cost little and bring much joy. If you don’t have the space, perhaps you can join forces with your neighbours or connect with a local community garden. If there isn’t a community garden, start one! The rooftops of apartment blocks are obvious places for kitchen gardens. The green plants will cool the air and beautify the space. If you find you really do have a green thumb, you may be able to sell your surplus and make some extra money.
Collecting this material is trivially easy: place a bucket in the kitchen and throw organic food scraps into it. Tough materials such as fish skins, bones, paper and wood decompose slowly, and odorous fats and meats can attract rats and insects; these are best avoided.
Composting requires ventilation and moisture. The disintegration of organic material is an oxygen-requiring aerobic process, rather than an anaerobic one: the model should be the forest floor, rather than a peat bog. You can set up composting buckets with air vents or turn over the compost regularly. You won’t need to purchase any additives, either. There are abundant nutrients and microorganisms in the compost as it is. If you add earthworms to your compost, it will break down much more quickly.
While techniques exist for recycling human solid waste on a small scale, these systems are best left to the experts. In some wilderness areas, you can see well-designed composting toilets to minimise the impact of human visitors.
There are vast amounts of information and equipment available to help you begin this wonderful healing cycle. Any gardener will be able to give you advice and it is very likely that your municipality will be able to help you get started. These projects are a critical part of civic planning, and good ideas abound.
The Urban Development Division of the World Bank identifies small-scale composting as a better option for developing countries than large-scale centralised projects. In all nations, no matter the level of urban development or the type of diet, we depend on the soil fertility for life. Industrial processes such as Haber’s method for fixing nitrogen have benefitted us greatly, but they have also altered the global nutrient cycle. We can, at the small scale, help to bring that cycle back to a more natural state. Composting not only helps reduce our waste stream, but also brings the vitality back into the Earth’s soil.
YD Bar-Ness is a conservation ecologist based in Fremantle, Western Australia. As a scientist, he specialises in climbing trees to explore the canopy biodiversity and as a conservationist, he seeks to use geography and photography to create environmental education materials.