Originally published in the Chat 'n Chew Café (6 May 1999). Updated January 2000.

Corn Yield Trends for Indiana
1930 - 1999

R.L. (Bob) Nielsen, Agronomy Department, Purdue University, West Lafayette, IN 47907-1150
Internet address: rnielsen@purdue.edu

Since 1930, state average corn grain yield in Indiana has increased at a fairly constant 1.6 bushels per acre per year as a result of improved genetics and production technology. As of 12 January 2000, the National Agricultural Statistics Service estimated that the Indiana corn crop will yield 132 bushels per acre in 1999. Such an estimated grain yield would be 2.2 % below the estimated trend yield of 135.0 bushels (Fig. 1).

Corn yield trends for Indiana
Fig. 1. Yield Trend Since 1930 (all years)


Annual grain yield values fluctuate above and below the trend line throughout the nearly 70 year period of records, but four disaster years are especially noteworthy. Late planting plus early fall frosts in 1974 resulted in state average corn yields 25% less than the trend value. Severe droughts in 1983, 1988 and 1991 resulted in yields 33%, 29% and 25% less than trend values.

Because the departures from trend for these four years are so dramatic, it is of some interest to calculate the trend line for corn grain yield without their inclusion. In so doing, the annual rate of yield increase is slightly greater (1.7 versus 1.6 bu/ac/yr) and the estimated trend yield for 1999 changes from 135 to nearly 141 bushels per acre (Fig. 2). Such values may be more true estimates of statewide yield potential in "normal" years. Given that assumption, the January 2000 Indiana grain yield estimate of 132 bushels per acre would be about 6.2 % below the trend yield.

Corn yield trends for Indiana - No disasters
Fig. 2. Yield Trend Since 1930 (without disaster years)


The top five U.S. corn grain producing states are Iowa, Illinois, Nebraska, Minnesota and Indiana (Fig. 3). As of November 1999, these five states (6.194 million bushels) account for over 64 % of the total estimated grain yield for the U.S. in 1999 (9.537 million bushels).

U.S. Corn Production
Fig. 3. Top Five U.S. Corn Producing States


For More Information...

For more statistics about Indiana agricultural production, "surf" on over to the home page of the Indiana Agricultural Statistics Service at http://www.aes.purdue.edu/agstat/nass.html.

Corn Growers' GuidebookFor other information about corn, take a look at the Corn Growers Guidebook on the World Wide Web at http://www.kingcorn.org/

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