Photo: SEDACMaps (flickr)
It’s common knowledge: a well-fertilized field will produce a greater crop yield than one left to grow without.
“Putting fertilizer on the ground on a one-acre plot can, in typical cases, raise an extra ton of output,” says Columbia University economist Jeffrey D. Sachs.
Fertilizer replenishes the supply of many key soil minerals that have been depleted by decades of farming. The most important of these are nitrogen, potassium, and phosphate–derived from phosphorus.
For the production of inorganic fertilizers, phosphorus is mined from underground deposits of phosphate.
85 percent of those deposits are in Morocco. 5 percent are distributed across China, Jordan, South Africa, and the United States.
There are no other high-density sources of phosphate in the world.
If we fail to develop new ways to find phosphorus for our fertilizers, we risk triggering a phenomenal collapse in food security.
Phosphorus plays an essential role in photosynthesis, the process by which plants absorb energy from the sun.
It encourages bloom, leaf, and root growth.
Plants starved of phosphorus often suffer from stunted growth in stem, leaves, and roots. Their green color becomes less vibrant; leaves may turn reddish at the base, or simply die and fall off.
A plant given insufficient phosphorus as a seedling may not recover, even if it is given more phosphorus later.
Photo: Pat Dalton... (flickr)
To avoid suffering a phosphorus deficiency in future, experts advise two major changes now: decreasing phosphorus and fertilizer wastage, and developing alternative sources of phosphorus to complement the use of phosphate rock.
A major source of phosphorus waste is, simply, that as fertilizer dissolves in irrigated fields, much of its phosphorus is carried away in water runoff instead of being absorbed into plants. Excess phosphorus in runoff water has the additional impact of causing overgrowth of algae and other aquatic plants, often damaging their ecosystems.
The Global Phosphorus Research Initiative advocates developing methods to extract phosphorus from human and animal waste so that it can be recycled into fertilizer.
How Urgent Is Urgent?
Nobody contests the fact that the earth’s supply of phosphate is finite, and therefore that alternative sources of phosphorus must be cultivated.
But it’s important not to overstate the case.
A September 2010 study by the non-profit organization IFDC (International Fertilizer Development Center), which is devoted to the study of international food security and the alleviation of hunger and poverty, asserts that there is no reason to expect phosphate reserves to run out within the next century.
Common assessments of the volume of global phosphate reserves only take into account deposits of high purity and easy access. But as the price of phosphate will inevitably increase over time, the extraction of phosphate from more expensive, less-dense reserves will become economically viable.
Still, say the IFDC, “Phosphate rock is a finite resource – at some point in time the earth’s supply may be exhausted. There should be a global effort to develop more effective phosphate rock mining and processing technologies and to utilize phosphate fertilizer, other phosphate-based products and phosphate-containing waste as efficiently as possible, while keeping unused nutrients out of watersheds and the oceans.”