The Worlds Food Supply Versus Eutrophication
Fred Pearce (environmental consultant for New Scientist magazine) - Phosphate has been essential to feeding the world since the Green Revolution, but its excessive use as a fertilizer has led to widespread pollution and eutrophication. Now, many of the world’s remaining reserves are starting to be depleted.
Phosphorus is one of the building blocks of all life. Every living cell requires it. Plants need phosphorus to grow as much as they need water. Many soils do not have enough to meet the voracious demands for phosphorus of the high-yielding crop varieties of the Green Revolution. But we can provide more by mining phosphate rock and turning it into fertilizer to spread on the land.
It takes one ton of phosphate to produce every 130 tons of grain, which is why the world mines about 170 million tons of phosphate rock every year to ship around the world and keep soils fertile.
the U.S. Geological Survey says that of the 65 billion tons of the world’s known phosphate rock reserves — and the estimated 16 billion tons that might be economic to mine — almost 80 percent is in Western Sahara and Morocco. Add in China’s reserves, and the figure rises to almost 90 percent. The U.S., with 1.4 billion tons, is close to running out. You can see why agronomists are starting to get worried.
Phosphate strip mines are environment wreckers. They produce around 150 million tons of toxic spoil a year. Their massive draglines, huge slurry pipes, and mountainous spoil heaps dominate the landscape for tens of miles in key mining zones, whether in the North African desert or in Florida, a state that still provides three-quarters of American farmers’ phosphate needs
The world’s largest mine is at Four Corners in an area known as Bone Valley in central Florida. The Four Corners mine covers 58,000 acres, an area five times the size of Manhattan. It is owned by Mosaic, a company recently spun off from agribusiness giant Cargill. Next door is the world’s second-largest mine, South Fort Meade. But South Fort Meade is living on borrowed time — its expansion plans are being opposed by local groups, and unless it can expand, the mine will have to close.
So How Can We Stop Phosphate Pollution
As for the impending shortages of phosphate, will technological advances and market forces solve the problem? We certainly waste a lot of this most valuable resource. Globally, we allow some 37 million tons of phosphorus to spill into the environment each year. It mostly flows down sewers and agricultural drains into rivers and lakes, where it feeds the growth of toxic cyanobacteria and consumes oxygen, creating eutrophication and “dead zones.”
Recycle it, and keep it in the food chain where we need it? Composting crop residues would be a good way of recycling this valued nutrient back into the soil, cutting the need for new applications of fertilizer — so would capturing some of the 3 million tons of phosphorus that cycles through human bodies annually, after being consumed in our food. Cordell says we should give top priority to recycling our urine, which contains more than half of all the phosphorus that we excrete.
Another possible solution could be Sustainably Controlled-Environment Agriculture limiting by-product waste. Aquaponics, using a natural fertilizer source, which is derived from fish waste. Aquaponics is a fully integrated system that produces both fish and plants. without the need for Phosphate based fertilizers and limiting the risk of contaminating our precious water supply, waterways and oceans.