Following up on the 2021 Corn Yield Guide, this week’s post reviews the historic soybean yield data and considerations for 2021. USDA’s May WASDE report estimated initial soybean yield for 2021 at 50.8 bushels per acre (bpa), up from 50.2 last year but not quite to the record levels set in 2016.
Historic U.S. Soybean Yields
Since 1988, the slope of the U.S. soybean yield curve has been 0.55 bpa per year (Figure 1). On a relative basis, that 0.55 bpa slope is equal to 1.7% of trend yield in 1988, which is slightly less than corn’s yield curve slope of 2.0% of the 1988 trend.
In 2020, U.S. soybeans yields were 50.2 bushels per acre (or, 0.7 bushels above trend). The highest reported yield was 51.9 bpa in 2016. Overall, soybeans have recorded consistently strong yields in recent years, with only one year of below-trend in the last seven.
Soybean Yield Trends
In addition to the trend yield of 50.1 bpa, Table 2 provides some insights into the range of possible outcomes in 2021. First, note that yields beyond +/- 5 bushels of the trend are pretty rare. Only twice have soybean yields slipped below -5 bushels from trend, and only once above +5 bushels from the trend.
For 2021, these data and methods suggest the historical range of soybean yields in 2021 terms is 43.8 bpa to 56.2 bpa. It’s also worth noting 2012 was not the worst year for soybeans, at least by this measure. This is important as we often hear comparison to “2012-like events,” which would have different implications across corn and soybeans.
Forecasting Soybean Yields
To dig even deeper into the data, AEI Premium users can follow along with our 2021 Yield Model Project for weekly updates from three models tracking this year’s corn and soybean yield forecasts. We started June with new expectations.
AEI Premium users can update their forecasts for the following question on this topic.
As you consider this question, it is important to remember the significance of small changes in soybean yields. Let’s consider the WASDE report and various yield estimates, which are reported to the tenth of a bushel.
For both crops, the smallest change (0.1 bushels) is equal to 0.2% of trend soybean yields in 2021 and 0.06% of corn. The goal here is to point out how hypersensitive some of these small changes are within the crops. Broadly speaking, a 0.25-bushel change in soybeans is roughly the same as a 1-bushel change in corn.
Wrapping it Up – Expectations for Soybeans in 2021
As discussed with corn, the May 2021 WASDE report includes a yield estimate that’s among the top two or three observed in history. But – this isn’t an ambitious forecast, but largely the influence of the upward sloping yield curve.
Diving into the data a bit, we can account for that upward slope over time and – similar to adjusting for inflation – create some helpful benchmarks. First, the trend-adjusted average yield for 2021 is 50.1 bushels. Second, the range of possible outcomes is likely +/- 6 bushels. Finally, we know above-trend yield occurs a majority of the time or roughly 55% of the time.
Of course, questions (especially when it comes to the weather) remain about how the 2021 growing season will play out. But historic data can provide a helpful baseline to frame expectations.