science stuff : peak phosphorus, food for thought
If you’re anything like me, you like to eat. In fact, if you’re anything like any human being on the planet, you like to eat. Without food we end up dying. So it figures that anything to do with ‘food security’ should be on our proverbial plate. It scared me somewhat that ‘peak phosphorus’ had been flying under my environmental radar. If the world runs out of phosphorus, we run out of food.
If you’ve never heard of phosphorus before, let alone peak phosphorus, let me explain. Phosphorus is one of the essential chemical elements of life. It is used in our bodies to form bones, teeth, proteins, cell membranes, DNA and many other biological structures. We receive the phosphorus we need from the food we eat. Plants take it from the soil and concentrate it into food, where it is then removed from the fields when harvested. To replace this constant flow of phosphorus, farmers must add fertiliser in the form of phosphates. If you’ve ever bought a bag of fertiliser yourself and seen a N:P:K ratio on the side, phosphorus is the P. Plants, and therefore food, cannot grow without it. There is absolutely no substitute or alternative. It is currently mined from a non-renewable resource called phosphate rock and it is slowly running out.
It’s hard to know exactly when the earth will run out of phosphate rock, but current estimates say sometime in the next 50-100 years. Just four countries, China, Morocco and the Western Sahara, South Africa and the USA, control most of the world’s reserves. China has already used trade tariffs to prevent the export of its supplies and the USA is expected to run out by 2030. While Australia has some phosphate rock mines, we remain a net importer of phosphates for fertiliser. This means that our agricultural production and our domestic food supplies are to an extent dependent upon foreign suppliers, some of which are located in politically unstable areas. Just as with oil, as production declines the price of phosphate will continue to go up, increasing the cost of food. In 2008 the price increased 700% making it unaffordable to many of the worlds poorer farmers and contributing to riots in India.
So what is the solution to dwindling supplies of a vital agricultural input? How will we continue to feed the growing population of Earth when one of the essential elements of food is running out? The answer is recycling, and it might have some of you feeling a little bit squeamish.
As a chemical element phosphorus is never really “used up” and it isn’t destroyed in the process of plant or animal growth. In the natural world it moves through the environment by means of the phosphorus cycle. Plants absorb it from the soil and it is transferred to animals when they eat. Most of the phosphorus passes out of the animals in their urine or droppings and fertilises the soil, as do decaying plants and animals.
While we need a constant supply of the phosphorus, we also excrete it. Our dairy and meat rich diets are a particularly high source of the element and most Western diets provide far more than we need to survive. So our bodies excrete it. Phosphorus leaves our bodies in pretty much the only way it can, through our human wastes. Faeces and urine both contain a lot of phosphorus, and at the minute we’re literally flushing this valuable chemical down the drain. If we don’t look towards reclaiming the valuable nutrient content of our sewerage, it’s quite possible we’ll find our world food supply up the proverbial creek without a paddle.
Sewerage treatment varies Australia wide and some councils already reclaim all the nutrients from waste and reuse them on crops. Other councils treat the water and let the nutrient load wash into streams, rivers and ultimately the sea, where the excessive levels lead to algal blooms and environmental issues. It’s a simple, logical step to start reclaiming nutrients, a win for farmers and a win for the environment. Parts of Europe are already trialling schemes and toilets for urine reclamation and subsequent use by farmers as fertiliser. There are technologies in development to make phosphorus recycling more mainstream, but as with the renewable energies, it’s a slow process.
The biggest problem seems to be that the potential phosphorus shortage has not yet gained widespread media coverage or activist support. While many of us (rightly) spend our time campaigning for action on climate change we often remain unaware of this similarly serious issue. If we want the world to keep eating through to the end of the century, we need to start planning for action now. Because hunger isn’t just a game.
By Joee Kelk
