Writing in the journal Agriculture and Human Values, the research warns that weak adherence to recommended organic practices may be behind the levels of greenhouse gases coming from large-scale organic farming operations.
Led by Julius McGee from University of Oregon, the team noted that while the findings may appear troubling, the study really points to the need for a reassessment of where the organic-food movement wants to go and how to get there.
McGee suggests stricter adherence to sustainability-driven farm practices and increased governmental oversight of the profit-motivated move toward upscale, certified organic production.
"The big questions are what are we are doing when we shift from conventional to organic production, and what are the environmental consequences," he said.
"This study says that the organic farming industry is in the early stages. So far we don't see any mitigating effect on greenhouse gasses. We need to pay close attention to what processes in organic farming operations make them the sustainable alternative that we want them to be, and we are going to need to more strictly follow those."
The research team used US annual state-level data from 2000 to 2008 on organic and conventional agricultural greenhouse gases from all states but Louisiana. Alaska data were not available for the first two years.
McGee and his colleagues also collected data on socioeconomic and agricultural indicators believed to influence industry growth trends. They then analysed greenhouse gas emissions using a fixed-rate panel regression that allowed them to indirectly control for unseen variables.
The study does not rule out the possibility that large-scale organic operations eventually will reduce greenhouse gas emissions, but, for now, McGee said, higher emissions are likely to continue unless actions are taken to correct course.
He warned that as operations grow, it takes more machinery to do the work. In addition, the organic trend often focuses on single rather than rotated crops, and an increased use of organic pesticides and herbicides and the importing of manure-based fertilizers from other locations, he added.
"We are not going to solve all these problems with technology," said McGee. "The issue of agriculture and climate change doesn't derive only from technology.”
“Sure, that's part of it, but a lot of the issue is the social context in which we relate to food -- the idea that overproducing food at a level exceeding what we need -- for both forms of agricultural production."