New study examines the dangers of crop monocultures

A new study indicates that the global narrowing of diversity in crop types present major challenges for agricultural sustainability across the world.

The study, carried out by an international team of researchers led by University of Toronto assistant professor Adam Martin, used data from the U.N.’s Food and Agricultural Organization (FAO) to look at which crops were grown where on large-scale industrial farmlands from 1961 to 2014.

They found that within regions crop diversity has actually increased. But, on a global scale more of the same kinds of crops are being grown on much larger scales.

Martin said that the large industrial-sized farms in Asia, Europe, North and South America are beginning to look the same.

“What we’re seeing is large monocultures of crops that are commercially valuable being grown in greater numbers around the world,” said Martin, an ecologist in the Department of Physical and Environmental Sciences at U of T Scarborough.

“So large industrial farms are often growing one crop species, which are usually just a single genotype, across thousands of hectares of land.”

Soybeans, wheat, rice and corn alone occupy almost 50 per cent of the world’s entire agricultural lands, while the remaining 152 crops cover the rest.

It’s widely assumed that the biggest change in global agricultural diversity took part during the so-called Columbia exchange of the 15th and 16th centuries where commercially important plant species were being transported to different parts of the world.

But the authors found that in the 1980s there was a massive increase in global crop diversity as different types of crops were being grown in new places on an industrial scale for the first time. By the 1990s that diversity flattened out, and that diversity across regions has been declining ever since.

This decline in global crop diversity is an issue for a number of reasons, Martin said

“If regional crop diversity is threatened, it really cuts into people’s ability to eat or afford food that is culturally significant to them,” he said.

Further, the increasing dominance by a few genetic lineages of crops means that the global agricultural system becomes increasingly susceptible to pests or diseases.

Martin said he hopes to apply the same global-scale analysis to look at national patterns of crop diversity as a next step for the research. Martin adds that there’s a policy angle to consider, since government decisions that favour growing certain kinds of crops may contribute to a lack of diversity.

“It will be important to look at what governments are doing to promote more different types of crops being grown, or at a policy-level, are they favouring farms to grow certain types of cash crops,” he said.