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Angie Peltier

Angie Peltier
Former Extension Educator, Commercial Agriculture

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Hill and Furrow

Current topics about crop production in Western Illinois, including field crops research at the NWIARDC in Monmouth.
Figure. Soybean planting response over seven site-years in central and northern Illinois, 2010 - 2011. In the equation, PlDa = number of days after April 1. (Dr. Emerson Nafziger, University of Illinois)

Recent research on soybean planting date

Over the past two years, Dr. Emerson Nafziger, U of I Agronomist, has planted soybeans on four different dates throughout the season at four research stations in Northern and Central Illinois, including the NWIARDC. At the NWIARDC, these planting dates were April 14, May 5 and 20, and June 11.

Dr. Nafziger's group found that yields were highest at the earliest planting dates, declining with later planting (Figure). The decline in yields accelerated from mid-April to the June planting dates. Using an equation generated from these seven site-years, they found that for every day planting was delayed in April, yields were reduced by 0.1 to 0.2 bushels. As planting moved into May and June, yield reductions accelerated as planting was delayed. In May, every day that planting was delayed resulted in a 0.3 to 0.4 bushel yield reduction and in June every day of delay resulted in a 0.5 bushel reduction.

The data collected at the NWIARDC followed the larger trend observed across the northern and central IL regions.

Dr. Nafziger cautions that the results from 2010 and 2011 are not consistent with earlier studies on planting date and may not be representative of what would happen in most years. Historically in Illinois, little yield loss occurs with planting delays until after mid-May. The best management strategy may still be finishing corn planting and then moving onto soybean.

Dr. Nafziger's describing this research in the online Bulletin can be found at:

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