by Tim Wall
To a chemist, organic means that a compound contains carbon. To a farmer, it means using non-synthetic fertilizers and pesticides. It turns out that organic farming actually may make the soil more organic in the chemical sense too.
An analysis of 74 studies on the soils in fields under organic or conventional farming practices, found that over time the carbon content in the organic fields had significantly increased. For farmers, that means organic agriculture results in a richer, more productive soil with plenty of humus.
Although the carbon in the organic fields is good for the farmers’ wallet, the research didn’t find evidence that organic farming was trapping enough carbon in the soil to combat climate change. Extraneous sources of greenhouse gas emissions related to agriculture weren’t analyzed in the study, hence the study’s authors could not determine if organic farming was tilting the scales towards trapping more greenhouse gases than it released.
For example, soil-derived nitrous oxide (a greenhouse gas) emissions weren’t accounted for in the research. Nor were emissions resulting from the production of organic fertilizers. Energy-related emissions from farm machinery and irrigation, as well as emissions from livestock and manure, were also not measured.
The study’s authors noted that offsetting emissions with trapping carbon in soil only buys time and does not negate the need for emission reduction.
The study was conducted by an international team of researchers and published in the Proceedings of the National Academy of Science.