December 7, 2021

I, Science

The science magazine of Imperial College

Anna Ikarashi on how agriculture today will make it harder for future generations to feed themselves

fields shutterstock_215572900The largest threat to maintaining global food supply is the very act of farming, says a new study published recently in Science.

“Ever since humans developed agriculture, we’ve been transforming the planet and throwing the soil’s nutrient cycle out of balance,” said lead author Ronald Amundson of University of California, Berkeley. “Because the changes happen slowly, often taking two to three generations to be noticed, people are not cognizant of the geological transformation taking place.”

Soil is lost through farming since current practices erode soil much faster than the speed at which natural mechanisms produce soil. Nutrients are also drained much faster than they can be replenished naturally, and the future supply of essential nutrients – nitrogen, potassium, and phosphorus – looks gloomy. In the US, phosphorus reserves will be used up in three decades. In addition, nitrogen requires fossil fuels – which are already running out – for it to be converted into a usable form.

The nitrogen cycle

Worse yet for humanity is that cultivating soil releases enormous amounts of carbon, as soil is an important carbon store. This is especially a problem in polar regions, where frozen soils will thaw and release more carbon. “Warming those areas is like filling your freezer with food, then pulling the plug and going on vacation,” said Amundson. “There will be a massive feast of bacteria feeding on the food as the plug gets pulled on the stored carbon in the frozen soil. Microbes are already starting the process of converting the carbon to CO2 and methane.”

The researchers argue that nutrients should be recycled into soil, as they are mostly dumped as solid waste. “We have the skill set to recycle a lot of nutrients, but the ultimate deciders are the people who create policy,” said Amundson. “It’s not a scientific problem. It’s a societal problem.”

 Anna Ikarashi is studying for an MSc in Science Communication

Images: Aerial view of agricultural fields by Peter Gudella (Shutterstock); The nitrogen cycle (Wikimedia Commons)

Amundson, R. et al (2015) Soil and human security in the 21st century. Science 348;  DOI: 10.1126/science.1261071