Massive Loss of Crop Diversity in Just 34 Years Reveals the Rise of Monoculture

As monocultures become the norm in farming, crop diversity is dropping. Now, scientists have found that in just 34 years, farmers are growing fewer types of crops, which may be impacting the general ecosystem.

In this latest study, the researchers used data from the USDA's U.S. Census of Agriculture, which is published every five years from information provided by U.S. farmers. The team examined data from 1978 through 2012 across the country's contiguous states.

Croplands comprise about 408 million acres or 22 percent of the total land base in the lower 48 states. This means that changes in crop species diversity could have a substantial impact, not only on agroecosystem function, but also the function of surrounding natural and urban areas. Because croplands are typically replanted annually, theoretically crop species diversity can change fairly rapidly.

"At the very simplistic level, crop diversity is a measure of how many crops in an area could possibly work together to resist, address and adjust to potential widespread crop failures, including natural problems such as pests and diseases, weed pressures, droughts and flood events," said Jonathan Aguilar, one of the researchers, in a news release. "This could also be viewed as a way to spread potential risks to a producer. Just like in the natural landscape, areas with high diversity tend to be more resilient to external pressures than are areas with low diversity. In other words, diversity provides stability in an area to assure food sustainability."

In this case, the researchers found a large drop in crop biodiversity and an increase in homogenization of agricultural production systems. This could have far-reaching consequences for future agriculture. For example homogenization can lead to greater increases of disease or crop pests that may cause poor crop yields.

The findings are published in the journal PLOS One.

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