Advocates of organic farming have long portrayed it as friendlier to people and the earth. But a new study in one California county found a surprising effect as plantings grew: Nearby conventional farms applied more pesticides, possibly to overcome the increasing insect threat to their crops, the researchers said.
Understanding what’s happening could be important to prevent organic and conventional farmers from harming each other’s operations, said Ashley Larsen, the study’s lead author, in this week’s journal Science.
“We expect an increase in organic in the future. How can we make sure this doesn’t cause unintended harm?” asked Larsen, an associate professor at the University of California, Santa Barbara.
In contrast, the researchers found that pesticide use dropped when organic farms were surrounded by other organic areas; The team thinks this may be due to their common dependence on insects, which are natural enemies of agricultural pests. Organic farms are allowed to use certain approved pesticides, but often resort to “good bugs” that prey on pests first. “It appears that spatial clustering or concentration of organic areas may provide this benefit or this solution,” Larsen said.
Researchers analyzed 14,000 sites in Kern County, California, over a seven-year period.
According to USDA, although organic agricultural areas have been on an increasing trend since 2000, they still constitute less than 1% of all agricultural land. As this change occurs, Larsen and his team say keeping organic and conventional farms sufficiently separate could benefit both.
But many farmers, both conventional and organic, oppose the idea of policies that could restrict where different methods can be used. And some outside researchers have said more studies are needed before considering policy recommendations. They noted that the study did not measure the type or number of insects on different farms, meaning increased pesticide use may only be a precaution.
Still, the “impressive data set” makes the study useful in generating valuable questions about agricultural practices and pesticides, said Christian Krupke, who studies insects as a professor of entomology at Purdue University and was not involved in the study. The total number of insects is decreasing, but pesticide use is not decreasing, he said, describing what some scientists call the “insect apocalypse.”
Krupke said the research shows how conventional farmers treat nearby organic businesses as “focal points of potential outbreaks.”
David Haviland, an entomologist at the University of California, Berkeley, who was not involved in the research, agrees. He described the fight in Kern County to control the glassy-winged sharpshooter, which invades citrus groves and can infect grapes, almonds and some other crops with devastating plant diseases. Haviland said regional maps clearly show organic farms as “huge, incredible hotspots where this pest is present in large numbers.” As a result, traditional growers next door have been forced to increase their use of pesticides, he said.
Yichao Rui, an agricultural ecologist at Purdue, said such reactions from farmers are not always due to an actual increase in pests; Sometimes it’s just for “peace”. Katy Rogers, who manages an organic farm outside Indianapolis, said it’s a misconception that in many cases organic farmers are home to massive pest infestations.
“Most organic farms on a well-managed farm do not encourage pest populations,” he said. “First of all, we fight them with other means, because bad bugs can still ruin my crop.”
Studying the environmental consequences of organic farming is a worthy goal, Rui said, and both organic and conventional farms have room for improvement. But he thinks looking only at pesticide use doesn’t take into account factors such as human health, air and water quality, and ecosystem diversity that can be affected by different farming methods.
“We need to make a holistic assessment of the benefits and returns of all these agricultural practices,” he said.
Indiana farmer Brad Wetli, who grows grains conventionally, said he hasn’t noticed any changes in the pest control situation since his neighbor switched to organic farming four years ago. He thinks farmers can apply more pesticides to high-value crops like fruits, vegetables and nuts in California, while the row crops he grows like corn and beans aren’t as valuable per acre, so he thinks it will take a year. There was a bigger change in the number of insects he saw on his farm before he started spraying more.
Wetli was more interested in land management. He is mindful of growing cover crops and working to reduce tillage, which can cause soil erosion and pollute waterways, and he said organic farming sometimes still requires tillage.
Meanwhile, organic farmers expressed concern that the study addressed the effects of organic farms on conventional farms, but not the other way around. For example, according to the USDA, if a prohibited material is applied to their site, even accidentally, they can lose their certification for up to three years.
Walter Goldstein, a corn grower in Wisconsin who produces both organic and non-organic seed, grew up working on an organic farm amid conventional farms and still remembers the pesticide drift.
“There are some really weird smells,” he said. “Chemical smells. “They smell like factory smells.”
Jay Shipman, who owns an organic farm near another large organic farm in Kern County, said he enjoys farming alongside someone with similar practices; “not just because it’s economical,” but also “this is how I eat. This is how I want my family to eat.” But he added that he grew up with conventional farming and understands that trying to persuade farmers to do something different can be “hard to change, hard to swallow.”
Rogers, Indianapolis’ organic farm manager, has spent most of his life in conventional farming and says he was taught that organic farmers were “the enemy.” He is now deeply committed to a small church-run organic and regenerative farm with vegetables, beehives and hay.
Rogers can see the benefits of bringing organic farms together, but thinks separating organic and conventional farmers, as the researchers suggest, could be “even more polarizing.”
“At the deepest level, we all steward the land, and we all actually want to contribute,” he said.
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