Organic farming can cause harm

Washington – Organic farming is often touted as a more sustainable solution for food production, leveraging natural forms of pest control to promote ecofriendly cultivation.

But a new study published in Science on Thursday found that expanding organic cropland can lead to increased pesticide use in surrounding nonorganic fields, offsetting some environmental benefits.

These harmful “spillover effects” can be mitigated if organic farms are clustered together and geographically separated from conventional farms, say researchers.

“Despite policy pushes to increase the amount of organic agriculture, there remain key knowledge gaps regarding how organic agriculture impacts the environment,” says lead author Ashley Larsen, of the University of California.

Although organic agricultural practices generally improve environmental conditions, the trade-offs aren’t very well understood.

For example, organic fields may harbour more beneficial species that prey on insects, such as birds, spiders and predatory beetles and fewer pests. Or the lack of chemical pesticides and genetically modified seeds could mean they harbour more pests.

To find out, Larsen and colleagues analysed data on about 14 000 fields in Kern County, California, across seven years.

The area produces high-value crops including grapes, watermelons, citrus, tomatoes, potatoes and more, making it one of the most valuable crop-producing regions in the US. The team paired digitised maps of fields and crops grown on them with records of pesticide applications and whether a field had an organic certification.

“Surrounding organic agriculture leads to an increase in pesticide use on conventional fields, but also leads to a larger decrease on nearby organic fields,” says Larsen, with the effect manifesting primarily in insecticides, which specifically target insects.

The level of pesticides in conventional fields dropped the further away they were from organic fields.

But the situation could be remedied if organic fields were grouped together, the researchers found, based on a less-detailed national level analysis they also carried out. –