Just another organic yield comparison?

posted in: Science | 165
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Wheat and wndmills. Credit: Idaho National Laboratory (INL) Wind Energy Program www.inl.gov/wind

Today, PLOS ONE has published a paper that I co-wrote with Randa Jabbour and Steve Savage titled “Commercial crop yields reveal strengths and weaknesses for organic agriculture in the United States.” In this paper, we describe our analysis of USDA data to compare organic and conventional crop yield data for 25 different crops. But is this just another organic yield vs conventional comparison for partisans to throw at each other in debates? We hope not. We’d prefer to throw that “debate” out the window – and instead focus on where each form of agriculture is doing best and start a conversation about how we can improve them all by learning from each other.

The paper is a more robust version of an article that Steve wrote last October. After I read Steve’s article in Forbes, I asked him if he’d be interested in applying some statistical analysis and submitting his idea to a peer-reviewed journal. We also enlisted the help of Dr. Jabbour who is an agroecologist at the University of Wyoming with extensive research experience in organic systems, and after several months of work we finally have a publication that I think we’re all pretty proud of.

I know what you’re thinking: “Does the world really need yet another comparison between organic and conventional crop yields?” My honest answer is “probably not.” That said, I thought I’d provide a brief explanation here of what makes our analysis a little different from previous research, and why I think it is a contribution was worth our time and effort.

First, I’d like to address some things our paper is not. We are not saying that organic farming is better or worse than conventional farming, and our analysis simply can’t justify such a broad conclusion. Simply analyzing differences in commercial yields (as we have done) is insufficient to choose a “winner” with respect to farming systems. Lower yield is not, in itself, evidence that farming is “harming the environment.” From the article:

“But agricultural systems should not be judged on yield alone. A primary goal for agriculture of the future should be to produce enough food to feed a growing population, and to do so while minimizing the negative impacts of that production. Organic agriculture has demonstrable benefits to the environment on a per unit area basis, however, those benefits are often negated or reversed on a per unit production basis because organic systems tend to yield less per area.”

And that last line is why we feel it is indeed important to quantify the differences in yield. Organic agriculture has many benefits, but the reduced efficiency has the potential to cancel them out. There is typically a trade-off between crop yield and ecosystem services for any given plot of land. To maximize both yield and ecosystem health, it is important to quantify both yield and ecosystem health. Our paper is one small piece of this larger puzzle.

Several previous meta-­analyses have compared organic crop yields with conventional crop yields, most notably Seufert et al. (2012) in Nature, Ponisio et al. (2014) in Royal Society of London B Biological Sciences, and de Ponti et al. (2012) in Agricultural Systems. These analyses suggested that yields in organic agriculture lag significantly behind those of more conventional production systems. Most of the data these analyses used, however, came from published studies of controlled experiments. Agricultural research, by necessity, often takes a reductionist approach in order to best isolate and quantify the effect of interest. Additionally, research equipment, labor availability, and scale of production is typically much different between field research and commercial production. We don’t consider these differences between research and commercial production to be negative per se; in fact I employ similar methods in my own field research. However, because of these limitations, controlled research may not always accurately reflect the level of innovation and practical constraints of real-world production agriculture.

The differences between commercial production and field research don’t necessarily bias yield differences between organic and conventional systems in any systematic way, so I am certainly not implying that previous analyses are “wrong.” But we felt there was value in comparing the estimates from previous meta-analyses with real commercial production data. The analysis we present in this article offers this perspective, based on organic and conventional crop yield data reported to the United States Department of Agriculture (USDA) as part of their 2014 agricultural producer surveys. Our analysis uses USDA survey data representing over 10,000 organic farmers and nearly 800,000 hectares of organic farmland to estimate actual production differences between organic and conventional agriculture in the United States.

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Figure 1 from the paper shows some of the crops that yielded lower – and higher – in organic systems.

Our results are mostly in line with previous works, but with some interesting differences here and there. One of the more interesting results we found was that although most organic crop yields were significantly less than their conventional counterparts, organic hay yields consistently out-performed conventional hay. We found that there wasn’t a consistent relationship between the organic yield gap and conventional yield potential, as had been proposed in the past. In some crops, there were a few states that were able to produce similar or even better yields with organic production compared to conventional. But because of the geographic scale of the data we used, we couldn’t determine why that was the case.

We feel our paper shows that there are opportunities for both conventional and organic producers to learn from one another. Some crops (like potato) consistently illustrate large yield gaps and merit more organic-focused research to support these producers. But organic hay production consistently out-performed conventional, so perhaps there are organic practices that could be adopted by more conventional farms to improve efficiency. Organic dry edible bean yields were about 26% lower than conventional yields overall, but there were three states where the organic yields were greater than conventional. So could conventional dry edible bean producers in learn something from the organic producers in states where organic yields are greater? Could those same conventional producers not only improve yields but reduce their environmental impact? Or are some organic producers achieving high yields at the expense of the environment, depending on their water use and soil management? Our conclusion:

“Examination of commonalities and differences between organic and conventional production practices in states with the best and worst yield ratios could be informative. Detailed knowledge of these specific production systems is necessary to investigate these comparisons, presenting an important opportunity for cross-commodity collaboration as well. Our findings support the importance of research funding at the federal level to facilitate such collaborations which may be otherwise difficult to execute but which are crucial to improving the sustainability of US agriculture.”

DOI: 10.1371/journal.pone.0161673

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Where will the debate go next? What can get us to a situation where collaboration is the norm and not conflict?

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Andrew is an Associate Professor of Weed Ecology & Management at the University of Wyoming. He has a PhD in Agronomy with a minor in Statistics. He teaches undergraduate & graduate courses including Ecology of Plant Protection and Weed Science & Technology. His research focuses on developing sustainable weed management programs in agronomic crops.