Yield comparisons for organic and conventional agriculture

Article identifies differences and challenges

Cover Nature 485, 7397
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An article published in Nature compared the yields of crops grown by organic and conventional methods in 66 studies reporting 316 organic-to-conventional yield comparisons on 34 different crop species. The studies looked at certified organic systems with spatial and temporal scale comparable to the conventional systems with which they were paired. Studies needed to provide data on sample size and error.

In most cases, organic farming systems had lower yields than conventional farming systems. Well-managed organic systems were almost equivalent to conventional systems in many cases. However, the magnitude of the difference depended on climate, soil, and cropping system. The results showed that organic had lower yields than conventional, but the difference varied based on context. Yields of organic crops produced in temperate climates were closer to conventional yields, on average, than similar comparisons in tropical climates.  The studies in tropical systems were based on yield comparisons of organic mainly with high-input systems in developing countries. Subsistence farming systems—a prevalent way of farming in many parts of the world—were not included.

The authors stated that "[n]ot a single study comparing organic to subistence systems met our selection criteria and could be included in the meta-analysis. . . Fortunately, the Swiss Research Institute of Organic Agriculture (FiBL) recently established the first long-term comparison of organic and different conventional systems in the tropics. Such well-designed long-term field trials are urgently needed."

Yield is only one parameter, and the authors acknowledge that other relevant factors related to meeting nutritional requirements are not taken into account in the studies reviewed. Environmental impacts appear to be lower on a per-hectare basis with organic, but overall impact is difficult to estimate. Economic benefits of organic farming to small-holder economic viability and food security are also not factored into the study.

The authors' recommendation is that "[t]o understand better the performance of organic agriculture, we should: (1) systematically analyse the long-term performance of organic agriculture under different management regimes; (2) study organic agriculture under a wider range of biophysical conditions; (3) examine the relative yield of smallholder agricultural systems; and (4) evaluate the performance of farming systems through more holistic system metrics."

The issue of Nature includes a discussion by John Reganold of Washington State University and Achim Dobermann of the International Rice Research Institute.

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Citations

  • Seufert, V., N. Ramankutty and J.A. Foley. 2012. Comparing the yields of organic and conventional agriculture. Nature 485: 229-232. Available at http://www.nature.com/nature/journal/v485/n7397/full/nature11069.html
  • Reganold, J. 2012. The fruits of organic farming. Nature 485: 177.
  • Dobermann, A. 2012. Getting back to the field. Nature 485: 177-178.

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