As the human population rises, so too does the anxiety about whether there will be enough food for all. Many have suggested that sustainable agriculture methods, such as organic production, are not suited to large scale adoption as a means of providing a reliable food source. Yet considering that our industrial agricultural system generates a plethora of environmental and public health problems, we have a real conundrum. How can we possibly secure sufficient food quantities without sacrificing the quality of our health or our planet’s?
Grappling with this question, scientists at University of California, Berkeley recently crunched the numbers on crop yields and found some good news. According to the analysis, led by Lauren Ponisio (and published today in the Proceedings of the Royal Society of London), there is evidence that sustainable agriculture – when done right – may have the potential to match the productivity of our dominant agricultural systems.
Credit: Paula R. Westerman
(Re-) doing the math on sustainable agriculture
To understand what Ponisio and colleagues have discovered, and how they did so, imagine trying to answer the question, “Which approach produces more food: conventional or sustainable agriculture”? If you asked me, I’d dream up a massive experiment with thousands of farms; different soils, crops, and management; and a variety of (controlled) weather scenarios. But, in the regrettable absence of limitless land, funding, and control over the weather, what’s the next best approach?
Although the perfect set of studies comparing conventional to sustainable agriculture does not exist, what we do have are dozens of publications reporting yields from conventional versus organic management (organic is not equivalent to sustainable agriculture, but is similar and well-studied). Thus, for this study, the researchers sought out all suitable papers, a subset of which had been previously analyzed by other authors, and began evaluating an impressive dataset that included:
- 115 studies
- 1,071 comparisons of organic and conventional yields
- 38 countries
- 52 crop species
- >35 years
If you will, take a moment to think about the challenge here: each study was designed by different scientists to answer a different question and report different answers. Although comparing these studies can be a bit like comparing apples and oranges (I’ll spare you the details, thoroughly described in the paper), the authors went to great lengths to identify and extract meaningful comparisons.
So what did they find?
- Organic yields are lower than conventional yields, but the gap is smaller than previously reported: A sophisticated analysis confirmed that organic yields are currently, on average, lower than conventional yields. However, the new analysis estimated that organics trail conventional crops by 19.2% (+/- 3.7), a lower amount than estimated by two other recent analyses.
- Diverse organic farms already produce nearly as much food as conventional farms: In cases where agricultural diversification strategies were employed (i.e., where farmers strategically planted more than one crop in their fields), organic fields produced nearly as much as conventional fields. Specifically, organic fields that used multi-cropping (diversification over space) or crop rotations (diversification over time) had yields that were 9% (+/-4) or 8% (+/-5) lower, respectively, than conventional equivalents.
- Agricultural yield – just another case of getting what you pay for: Of the many crop types analyzed, cereals had the greatest yield gap between organic and conventional management. This fact should actually come as no surprise, since conventional cereal crops have received a significant stream of research funding since the Green Revolution. Should we really expect crop varieties that have been developed specifically for conventional systems to perform as well in sustainable systems?
- Signs point to bias in the dataset, suggesting that the yield gap may actually be lower: In analyses like this, scientists are dependent on existing data and must make the best of what’s available; statistical tests can then be used to identify potential bias. For this study, these tests indicated that bias in the dataset likely led to an overestimate of the yield gap between organic and conventional systems.
The bottom line
Today’s well-managed sustainable agriculture yields nearly as much as conventional equivalents, suggesting that it is possible to farm sustainably without sacrificing yields and, therefore, profits. That this finding emerged even despite both evidence of bias in the dataset (favoring conventional yields) and historic underfunding of research in sustainable agriculture is profound.
All in all, this study provides more evidence that agroecological approaches can help the world feed itself without the significant threats to environmental and public health posed by today’s dominant industrial-style approaches—an assertion supported by the nearly 300 scientists who have added their name to a statement calling for increased public investment in agroecological research. Science is suggesting, yet again, that this is an investment we can count on.