Scientists warn that humans have been depleting soil nutrients at rates that are orders of magnitude greater than our current ability to replenish the soil. Fixing this imbalance is critical to global food security over the next century. (iStockphoto)
Steadily and alarmingly, humans have been depleting Earth’s soil resources faster than the nutrients can be replenished. If this trajectory does not change, soil erosion, combined with the effects of climate change, will present a huge risk to global food security over the next century, warns a review paper authored by some of the top soil scientists in the country.
The paper singles out farming, which accelerates erosion and nutrient removal, as the primary game changer in soil health.
“Ever since humans developed agriculture, we’ve been transforming the planet and throwing the soil’s nutrient cycle out of balance,” said the paper’s lead author, Ronald Amundson, a UC Berkeley professor of environmental science, policy and management. “Because the changes happen slowly, often taking two to three generations to be noticed, people are not cognizant of the geological transformation taking place.”
In the paper, published Thursday, May 7 in the journal Science, the authors say that soil erosion has accelerated since the industrial revolution, and we’re now entering a period when the ability of soil, “the living epidermis of the planet,” to support the growth of our food supply is plateauing. The publication comes nearly two weeks ahead of the Global Soil Security Symposium at Texas A&M University, a meeting held as part of the declaration of 2015 as the International Year of Soils by the United Nations.
A future ‘phosphorous cartel’
The authors identify the supply of fertilizer as one of the key threats to future soil security. Farmers use three essential nutrients to fertilize their crops: nitrogen, potassium and phosphorous. The paper credits the discovery of synthetic nitrogen production in the early 1900s for significantly increasing crop yields, which in turn supported dramatic growths in global population. Because the process of synthesizing nitrogen is energy-intensive, its supply is dependent on fossil fuels.
Unlike nitrogen, potassium and phosphorous come from rocks and minerals, and the authors point out that those resources are not equitably distributed throughout the world. The United States has only 1 to 2 percent of the world’s potassium reserves, and its reserves of phosphorous are expected to run out in about three decades.
“This could create political challenges and uncertainties,” said Amundson. “Morocco will soon be the largest source of phosphorous in the world, followed by China. These two countries will have a great deal of say in the distribution of those resources. Some people suggest we will see the emergence of a phosphorous cartel.”