Scientists sound the alarm. We need to change the way we deal with phosphorus very quickly, otherwise a global phosphorus crisis threatens.
The Dutch fields are full again; the corn shoots up, the ears of corn dance in the wind and the potatoes wait patiently to be harvested. The fact that the crops are so prosperous is partly due to phosphorus: a mineral that is indispensable if you want to grow food. It promotes root growth, is necessary for photosynthesis and aids in the absorption of other elements, nutrients and water. Phosphate (the chemically bonded form in which phosphorus occurs in most compounds) is thus an essential mineral. However, most soil types have a low phosphate content and therefore it is necessary to add phosphorus to the soil for a good harvest. And that is also done on a large scale, by fertilizing the soil with phosphate fertilizer.
“Those phosphate fertilizers are extracted from phosphate ores,” says Kimo van Dijkresearcher at the Wageningen University & Research and one of the authors and reviewers of the recently published report Our Phosphorus Future in which the looming global phosphorus crisis and possible solutions are described in detail. “Phosphate ores – just like petroleum, for example – are extracted from fossil layers, which formed because dead sea creatures sank to the bottom of inland seas long ago.” This means that phosphate ores – just like fossil fuels, for example – are finite: they will eventually run out. “It is unclear how much we still have at our disposal and it also strongly depends on supply and demand and whether we recycle,” says Van Dijk. “Alarmists think we can use it for another 50 years with our current consumption, but the fertilizer industry thinks there is still enough for about 400 years. Let’s say the truth is probably somewhere in the middle and we can go on for another 100 to 200 years.”
One thing is clear: if we continue on this path, the phosphate ores will run out. But in the run-up to that doomsday scenario, other problems also arise. “For example, you see a decreasing quality of the phosphate ores that are extracted from the remaining sources, with lower concentrations of phosphorus and higher concentrations of contaminants. These phosphate ores are ‘dirtier’, with, for example, cadmium and other substances that you do not want in your soil and food. These ores then have to be cleaned up first, which increases the price.” Higher fertilizer prices are already threatening food security in some places, as phosphate fertilizers threaten to become unaffordable for some farmers.
Moreover, the price of phosphate fertilizers can quite easily be pushed up further by geopolitical developments. For example, about 85 percent of the phosphate reserves known to us can be found within the borders of just five countries, including China, Morocco and Russia. “In the case of Europe, only a very small part of the phosphorus, about 10 percent, comes from Europe itself, namely from Finland. For the other 90 percent, we depend on imports, for example from Morocco and Russia.” And in recent months it has become painfully clear how vulnerable you can become in times of conflict and associated sanctions if you depend on others for essential raw materials. And not only conflicts can sometimes throw a spanner in the works; In the past, both China and Russia have stopped exporting phosphorus because their own farmers desperately needed it.
On the one hand, scarcity, disappointing quality and geopolitical challenges threaten to create shortages in both the short and long term, with major consequences for food security. “Because again: without phosphorus you cannot grow food.” But the phosphorus crisis is more than that. On the other hand, we also see that the use of phosphate fertilizers leads to problems in many places. “Of the net import of phosphate into the EU, roughly half accumulates in soils and the other half is lost via waste streams, in infrastructure and landfills. A smaller proportion of 5 to 10 percent ends up in surface water due to runoff and leaching from the soil. Relatively speaking, this is only a small stream, but it does have a major impact on nature and the environment.” Because you would rather not have those fertilizers there. “It is bad for water quality and therefore also for biodiversity. In some places, it even results in irreversible ecosystem change.” Van Dijk is thinking, for example, of eutrophication in the Baltic Sea and many lakes and ditches. “There is little water exchange here and when nutrients such as phosphate are added from agriculture and waste water (see box, ed.), they also remain in that water. This can make the water cloudy and oxygen-free, for example, causing fish death and a change in the animal and plant species that occur naturally here.”
The problem is clear: we are rapidly extracting phosphate from the rather scarce phosphate mines and at the same time we – unintentionally – bring phosphate to places where we actually do not want it. It is a two-headed crisis in the making. But it is not too late to change course, emphasize Van Dijk and colleagues in the recently published report that we mentioned above. Because if we continue in this way, we will run out of phosphate fertilizers – “We can’t make extra phosphate, but luckily we can recycle it.” Depletion of the phosphate mines can be prevented by recycling phosphorus, something that is hardly happening at the moment. “All the phosphorus that has been mined to date can still be found on Earth,” says Van Dijk. “It cannot leave this Earth unless you shoot it into space. The problem, however, is that in the current linear system we extract the phosphate from the mines, but then continue to dilute it continuously. Think of accumulation in agricultural land, via leakages to the surface water and ultimately the sea, and by, among other things, burning sludge and dumping the ashes with phosphate or fixing them in roads and concrete.” That must and can be done differently. “Because in order to be able to recycle the nutrient, preferably for agriculture, you want to keep it as concentrated and clean as possible.”
But how can we recycle and secure the ‘used’ phosphate? We could start reusing the phosphate that people put into the sewage through their faeces. “Nutrients such as phosphate are currently still precipitated during the purification of the waste water, creating sludge, which sludge is simply incinerated in the Netherlands. In our country, for example, we lose more than 10 million kilos of phosphate and it is no different elsewhere in the world.” Ideally, you naturally want to retain those phosphate flows within the food system, but in practice that proves to be difficult. “The current wastewater system is centrally organized in which faeces and pee get mixed with other (dirtier) domestic wastewater, rainwater, but also with wastewater from the garage and the painting company around the corner.” The result is that the phosphate becomes very diluted and becomes contaminated. “The sewage also contains heavy metals and medicine residues, for example, which makes it difficult to return nutrients to the cycle in a safe and clean way. However, recycling is necessary for circular agriculture.” There is a solution, but it is quite drastic. “A decentralized wastewater system, in which faeces and pee are collected separately and to which SMEs cannot discharge and rainwater is not collected either.” This prevents dilution and pollution and makes it easier and safer to recycle nutrients. In addition, it is better to prevent nutrients and contaminants from ending up in nature from the sewer. However, it all sounds simpler than it is. “You can’t just adapt a sewer system, you have to open up entire streets for that, and that is certainly not feasible in large and historic cities. But with new neighborhoods and apartment buildings to be built and renovated, it is a serious option that simply has to be implemented. The transition to circular wastewater systems starts now!” says Van Dijk.
In addition to recycling, there are other ways to tackle the scarcity of phosphate and other nutrients. Think, for example, of reducing food waste. It is estimated that some 931 million tons of food are thrown away every year; if we don’t have to renovate that, a lot of phosphorus consumption can also be saved. Another important measure is the integration of livestock and arable farming, whereby high-quality fertilizers are produced from animal manure and used to fertilize crops instead of artificial fertilisers. In addition, as a consumer you can also contribute by making healthier diet choices. “In general, the production of plant-based foods requires less phosphate than the production of animal products, such as meat.” But garden owners can also take matters into their own hands and make different choices in order to contribute to a future in which phosphate fertilizers remain widely available. “As you think about which fertilizers to use in the garden, consider using your own urine. Especially if you don’t take medication, that’s fine. It is best to let it stand for a few months in a closed container that is as transparent as possible, to dilute it once just before fertilizing and to water it afterwards with a watering can. Or opt for organic fertilizers in the garden center instead of mineral fertilizers from the phosphate mines, or in the future when it comes on the shelves for struvite: a fertilizer full of phosphate and nitrogen, which is already slowly being recovered from waste water in the Netherlands.”
It has now been twelve years since Van Dijk started working on the phosphorus problem. And in those twelve years he has seen quite a few changes. “People are now more aware of the nutrient challenge – including at the water boards and in agriculture.” But at the same time, Van Dijk must also conclude that it has led to few concrete actions, let alone effects. “The conclusion can also be drawn that this is such a complex problem that the market will not solve it on its own. Guiding government policy is needed to find a solution in the chain and sectors.” And that shouldn’t take too long. “The time for non-commitment is over. Phosphate is an essential and non-replaceable nutrient; it must now be recycled. Otherwise, all that beautiful phosphate will be used up in a span of generations, soils will be depleted and food production will become increasingly difficult. Certainly with a declining livestock and a reduction in the manure surplus, circular agriculture will have to run on nutrients from compost and human faeces and pee. Of course in the safest way possible.”
†A sustainable direction for phosphorus will lead to better food production, cleaner waters, healthier people and greater biodiversity” – OPFGlobal
Interview with Kimo van WijkImage at the top of this article: