by To help California combat climate change, air quality regulators want 20% of the state’s farmland to become organic by 2045. That means converting about 65,000 acres of conventional fields to organic practices each year.
But depending on how that transition takes place, the change could lead to complete change. increase in the amount of pesticides used by growers across the state.
So suggests a new study in the journal Science that examined how organic farms affect the behavior of their neighbors. Researchers have found that when new organic fields come online, the insects that come with them can encourage traditional growers to increase their pesticide use by a large enough amount to offset the decline in organic fields—and then some.
“We expect an increase in organics in the future,” said study leader Ashley Larsen, professor of agricultural and landscape ecology at UC Santa Barbara. “How can we make sure this isn’t causing unintended harm?”
Organic farming practices help combat climate change by producing healthier soil that can hold more carbon and by avoiding synthetic nitrogen fertilizers, which encourage greenhouse gas emissions. Organic methods are also more sustainable for a warming world because they help the soil retain more water, among other benefits.
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For their study, Larsen and her colleagues took a deep dive into the farming practices of California’s Kern County, where growers regularly produce more than $7 billion worth of grapes, citrus, almonds, pistachios and other crops. Thanks to the county and the state, there are detailed records going back for years about how they do it.
The researchers examined about 14,000 individual fields between 2013 and 2019. They were able to see the shapes and locations of those fields, as well as whether they were growing conventional or organic crops and how many pesticides were used.
In fact, a key difference between conventional and organic agriculture is their approach to dealing with unwanted pests. Conventional farms may deploy toxic chemicals such as organophosphates and organochlorines, while organic farms prefer to keep harmful bugs under control by encouraging the growth of their natural enemies, including beetles, spiders and certain birds. They can also use certain pesticides, which are usually made with natural rather than synthetic ingredients.
These contrasting strategies make for complex neighbors. If destructive critters switch from an organic to a conventional farm, a grower may respond by using more pesticides. This, in turn, would undermine the helpful creatures that organic growers rely on. On the other hand, organic farms feed beneficial insects that migrate to other fields.
“Organic farms can be a blessing and a curse if they’re in your neighborhood,” said David Haviland, an entomologist with the University of California at Bakersfield’s integrated pest management program, who was not involved in the study.
By 2019, approximately 7.5% of the permitted fields in Kern County were used to grow organic produce. They were spread throughout the growing areas in the county, although many were grouped in clusters.
With their data in hand, the researchers created a statistical model to see if they could find a relationship between pesticide use in a given field and the presence of nearby organic fields.
For organic fields, they found that a 10% increase in organic cropland was associated with a 3% decrease in pesticide use. For conventional fields, the same 10% bump in organic neighbors came with a 0.3% increase in pesticide use.
Since conventional fields outnumbered organic fields, the net effect in Kern County was a 0.2% increase in pesticide use. Most of that was driven by additional insecticides rather than chemicals that targeted invasive weeds or damaged fungi, Larsen said.
“We think it’s fundamentally about a different reliance on natural methods of pest control,” she said. More bugs are bad for traditional farmers because it means more unwanted insects, she explained. But more bugs are good for organic farmers because it means that there are more natural enemies of the same pests.
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The researchers also used their model to simulate different possible farming futures to see if this overall increase in pesticide use could be avoided. The answer, they found, was yes.
One way was to increase the amount of land that is farmed organically. In their model, going from no organic fields to 5% of cropland being organic was associated with a 9% increase in insecticide use in Kern County. However, if 20% of agricultural land had organic crops — as the California Air Resources Board envisions — total insecticide use would decrease by 17%.
Those figures were based on a simulation in which organic fields spread out, which maximizes the pest control boundary sprays between organic and conventional fields. Where organic fields were clustered together instead, increasing their combined footprint from 0% to 5% of the total acreage was associated with a 10% reduction in insecticide use, and all the way to 20% of the total acreage with a 36% drop in chemicals, the researchers reported.
“Essentially what we see in the simulation is that while insecticide use may increase at low organic levels, it can be completely mitigated by spatially clustering organic croplands,” Larsen said.
It’s one thing to do that in a simulation; make it in the real world otherwise. An organic almond farmer whose orchard is near conventional fields cannot easily dig up his mature trees and replant them elsewhere. But as farmers switch more of their conventional fields to organic, the results of this study could help them decide where to focus their efforts to get the most benefit, Larsen said. .
Similarly, policy makers could identify certain areas where they would like to see organic crops and offer incentives to encourage growers to make the leap. In principle, it would be similar to the grants offered by the California Department of Food and Agriculture’s Healthy Soils Program, she said.
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Erik Lichtenberg, an agricultural economist at the University of Maryland, said the study made a “convincing case” that organic farms affect their neighbors, but that it would be important to know a lot more data before concluding that it’s a good idea. organic and organic separation. traditional farms.
Among other things, “I want to know more about why the fields are located the way they are, what you plant, and how that relates to the pest management strategies that the growers are following,” a said Lichtenberg, who wrote a commentary. attached to the study.
Haviland said the idea of clustering organic farms generally makes sense because it reduces the boundaries between organic and conventional fields. However, he noted that there are situations where clustering can make things worse.
Consider the glassy-winged sharpshooter, which spreads a disease that kills vines. Conventional farmers have tools to control them, but organic growers do not. When organic grapes are more isolated, an insect is more likely to fly from the field and “not come home” because it will encounter a pesticide nearby, Haviland said. But if all the organic fields were clustered together, they would be “greatly increasing their own problem by not benefiting from the traditional growers around them.”
Haviland also emphasized that “there is a misconception among the general public that all pesticides are created equal and that they are all bad, and that is certainly not true.” Reducing total pesticide use is valuable, but considering the types of pesticides is more important. used, he said.
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The statistical analysis alone does not prove that the addition of organic fields is responsible for the change in pesticide use, but Larsen said the circumstantial evidence of a causal relationship is very strong. The conventional fields that received an organic neighbor had the same pattern of pesticide use as their conventional counterparts, and only began to resolve after the neighboring field switched to organic.
“This is pretty strong evidence, in our minds,” she said.
Milt McGiffen, a cooperative extension specialist with the Department of Botany and Plant Sciences at UC Riverside, wasn’t so sure. He said growers make a point of planting organic crops in places where they know pest control won’t be a big problem because they can’t use conventional pesticides.
“The reason a group of organic farms are mostly together is because that’s where you have the least number of pests, not the other way around,” said McGiffen, who was not involved in the study.
He said there are many examples of governments trying to accelerate the transition to organic food production, but he is not aware of any effort to encourage growers to locate organic fields in specific locations.
“This study has some interesting ideas,” McGiffen said, but “some experimenter needs to go out there and test all of this.”
This story originally appeared in the Los Angeles Times.
