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The US Corn Belt and the summer chill | Watts Up With That?

US Corn Belt and Summer Chill?

Content added from wattsupwiththat.com/2013/0...summer-chill/

Guest essay by David Archibald

A correspondent in the Corn Belt emailed on 10th August:

“Here in north central Illinois at exit 56 on I-80, most of the corn was planted by May 15.

The GDD totals since May 15 at Moline, Illinois.

May 15-31 + 1.7 GDD >normal. June 1-30 – 32.7 GDD < normal. July 1-31 – 94.5 GDD < normal. August 1-9 – 33.9 GDD < normal.

Total since May 15 = 1695.0 GDD = -159.4 < normal, or about 8 normal days in early September. Corn that has a 2,500 GDD rating needs about 40 days yet. Most of the corn planted in NC Illinois is in the 2,450 GDD to 2,700 GDD maturity area.

The area of greatest risk is in IA north of Route 30, MN, WI and the Dakotas.”

Figure 1: Corn Futures and Production Forecast from the Wall Street Journal

The corn market doesn’t see a problem with corn prices off 30%-odd from where they started the year, as shown in Figure 1 at right.

To illustrate the problem in parts of the Corn Belt, Figure 2 shows the average Growing Degree Days (GDD) experienced in Northwest Indiana, fairly close to the center of the Corn Belt:

Figure 2: Average Weekly GDD for Corn in Northwest Indiana

From where we are at the time of the incoming correspondence, marked on the graph at 10th August, the heat received by the corn crop starts falling away.

Staying in Northwest Indiana, if we assume that the crop there was also 159 GDD below a normal season, Figure 3 illustrates the effect of on achieving the necessary 2500 GDD for crop maturity:

Figure 3: Northwest Indiana 2013 Corn Crop

The upper red line shows the cumulative GDD for a crop planted on 15th May if the season had been normal from that date. Under that case, 2,500 GDD would be achieved by 26th September well before the first frost date for the area. The season has been colder than average with GDD for July 15 per cent below normal. The green line shows the fate of the crop if the season reverts to normality from 10th August. Under that case, 2,500 GDD is reached by 17th October, very close to the first Fall frost date. The lower dark blue line shows the effect of the season being 10% cooler from here.

While we cheer on the Arctic sea ice extent, there are farmers in the northern half of the Corn Belt who are now concerned about how their crop will finish.

UPDATE: Lows this morning from Dr. Ryan Maue – Anthony