Let there be corn! Reality check on the 2012 drought and corn yields in relation to droughts of the past

There’s a lot of hype out there regarding the drought and its potential effects on crops. Predictions range from increased food prices to dustbowlification”, a term coined by “Joe Romm. A complicit media follows. Tom Nelson points out some interesting facts:

Drought to cost $12B, most since 1988 – USATODAY.com

The Kiwis think otherwise though, from radio New Zealand: July 26, 2012 : Worst drought in 50 years driving up US food prices

Food prices in the United States are expected to rise by 3% or 4% next year because of the worst drought in more than 50 years.  Corn, soybean and other commodity prices have all soared in recent weeks as fields dry out and crops wither in the heat. The drought, which is affecting much of the Midwest, is the worst since 1956.

What Drought Did to Crop Yields in the 1930s – Livinghistory.com

In 1930, Nebraska got 22 inches of rain, and the state’s corn crop averaged 25 bushels per acre. In 1934, Nebraska saw the driest year on record with only 14.5 inches of rainfall. The state’s corn crop dropped even more to only 6.2 bushels per acre.

[July 19, 2012]:  2012 Potential Corn Yields Based on July 15 Hybrid-Maize Model Simulations – UNL CropWatch, July

[See table 1 here: For five Nebraska locations, median forecasted yields for rainfed corn are 118-130 bushels per acre; for irrigated corn, the median forecasted yields are 228-245 bushels per acre]

From the University of Nebraska-Lincoln:

End-of-Season Yield Potentials as of July 15

Corn Yield Potential (Yp) forecasts, as well as the underpinning data used for the simulations, can be seen in Table 1. The long-term yield potential prediction based on 30 years of weather data (Table 1, fourth column from the right) is compared to the range of predicted 2012 corn yield potential (three columns on the right), which includes the yield potential simulated under the most likely scenario of weather expected for the rest of the season (median) and for relatively favorable and unfavorable scenarios for the rest of the season (75th and 25th percentiles) based on historical weather data.

According to the July 15 simulations, the “most likely” end-of-season dryland corn yield potential in Nebraska, Iowa, and southeastern Illinois (“median” yields, red column in Table 1) is 10% to 26% below the long-term average yield potential (Table 1). Even if weather turns favorable for dryland corn during the rest of the 2012 season, the resulting yields (75th yields, blue column in Table 1) are still likely to be below the long-term average (Table 1). How about if dry and hot conditions persist? Certainly the likehood and magnitude of yield reduction in dryland corn will increase. In fact, Hybrid-Maize predicts dryland corn yield potential to be about 30% to 40% below the long-term average if weather remains hot and dry for the rest of the season (25th yields, green column in Table 1). The only bright spots in this analysis were in Illinois at DeKalb and Monmouth where rainfall during the past two weeks appears to have provided relief. At these sites, current projects indicate that end-of-season yields will be near their long-term averages unless weather once again turns dry and hot at those locations (Table 1). Likewise, recent weather conditions at Brookings, S.D. have been conducive to achieve yields near the long-term average.

What about irrigated corn in Nebraska? Contrary to the projections for dryland corn, irrigated corn yield potential is only two to three bushels below the long-term average at Holdrege, Mead, and Concord (Table 1). High nighttime temperatures during the last two weeks at Clay Center have hastened crop development and increased nighttime respiration costs, leading to a projected yield potential that is 9 bushels below the long-term average. At O’Neill last week’s weather did not depart from historical temperature norms, hence, projected yield potential is still near-average. But it is important to keep in mind that if hot weather persists for the rest of the season, the likehood (and magnitude) of below-average yields will increase for irrigated corn due to more rapid maturation and a shorter grain-filling period.

Summary

Projected 2012 end-of-season yields are well below the long-term yield average for dryland corn in Nebraska, Iowa, and southeastern Illinois and near average in South Dakota and central-west Illinois. Projected yield for irrigated corn in Nebraska is slightly below average at most locations, except for Clay Center, which it’s 9 bushels below average and O’Neill where it’s near average. If hot, dry conditions persist during coming weeks, we expect projected yields will drop substantially under both dryland and irrigated conditions. We will continue to update these projections as the season progresses.

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The reality check is: Even with the bad news of reduced yields of regular corn at 22-42 bu/ac below average, and  trrigated corn  at 2-9 bu/ac below average,  2012 Nebraska corn yields are still forecasted to be 20-40 times the  1934 Nebraska corn yields.

Yes it was really so much worse in the 1930’s than the present:

h/t to Steve Goddard and this EPA report for the above graph and points.