U.S. corn planted in the middle of April, which is the norm, is beneficial to yields while planting earlier than that generally results in a "flat yield response," according to agronomists at the University of Illinois at Champaign.
The hottest start to March since records began in 1871, with record-high temperatures for a week straight in Chicago, has had some U.S. Midwest farmers planting corn earlier than ever.
Even if the corn is not killed by frost, the benefits of planting early are likely to be minimal, the agronomists said in a report on Friday.
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In typical years, corn planted early in April can sit in cool soils before germinating, or the plant’s emergence can slow in should April turn cold.
The farmers risk losing their crops to frost and most insurance companies will not cover replanting costs until after the earliest planting date, April 11 in No. 1 corn state Iowa and April 6 in most of Illinois, the No. 2 corn growing state.
However, yields are likely to suffer if corn is planted late, with yields dropping precipitously for corn planted beyond mid-May, Emerson Nafziger, extension agronomist at the University of Illinois, said in an interview.
"Planting early to avoid planting late is one of the strategies," Nafziger said.
In central Iowa, corn planted between April 15 and May 18 had a 95 to 100 per cent chance of achieving maximum yield potential while corn planted in a slightly narrow window, between April 15 and May 9, had a 98 to 100 per cent chance of achieving the best yield, according to Iowa State University.
The average U.S. corn yield was 147.2 bushels per acre in 2011, down 5.6 from the previous year and off the record yield of 164.7 in 2009, according to the U.S. Agriculture Department.
