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May 12, 2011

Early U.S. Yield Estimates - Corn 158.7 bu/ac, Soybeans 43.4 bu/ac

In the recent WASDE report the USDA estimated the 2011 U.S. corn yield at 158.7 bushels per acre which is approximately 3 bushels per acre below the trend line yield. Their stated reason for the reduced yield was the lateness of the planting especially in the eastern Corn Belt and the northwestern Corn Belt. The corn planted area was left unchanged from the March Prospective Planting Report. For the 2011 U.S. soybean crop the yield was estimated at 43.4 bushels per acre and the planted acreage was also left unchanged from the March Prospective Planting Report.

These estimates are significantly below some of the early estimates of last year (165-170 bu/ac for corn and 44-46 bu/ac for soybeans) when the crops were planted at a record fast pace. It was assumed in early 2010 that the record planting pace would result in above trend line yields, but adverse weather in May and June of 2010 resulted in disappointing yields.

The general rule of thumb is that the later the corn is planted, the lower the potential yield for the crop due to the following reasons:

  • Later planted corn pollinates later in the summer when there is a greater chance of hotter and dryer conditions that might impeded successful pollination.
  • As planting is delayed, farmers might switch to earlier maturing corn hybrids which generally have a lower yield potential compared to full season hybrids.
  • Later planted corn also has a lower leaf area index during the times of peak solar radiation, resulting in less photosynthate being manufactured and lower yields.
  • Later planted corn also runs the risk of maturing later in the fall when there is a greater chance of a killing frost.
  • The planting date is just one of many factors that can affect corn yields. A quick look at the affect on yield due to delayed planting in some of the key producing states revels the following:

    Ohio - If corn in Ohio is planted during the second week of May, it has 92% of the maximum yield capacity, planting during the third week of May results in 87% of the maximum yield, and planting during the fourth week of May results in 79% of the maximum yield capacity.

    Indiana - The estimated yield loss for each day that planting is delayed varies from 1 bushel per day for each day delayed in early May to 2 bushels per day for each day delayed in late May.

    Illinois - In central Illinois, if planting occurs during May 1-10 one bushel of yield is lost per day for each day that planting is delayed. If planting occurs between May 11-20, the loss is 1.5 bushels per day. If planting occurs between May 21-30, the loss is 2.1 bushels per day.

    Minnesota - In southern Minnesota, if planting occurs on May 10th, it has 94% of the maximum yield capacity. If planting occurs on May 15th, it has 91% of the maximum yield capacity. If planting occurs on May 20th, it has 88% of the maximum yield capacity. If planting occurs on May 25th, is has 86% and on May 30th, it has 83% of the maximum yield capacity.

    Each state varies slightly, but the general rule of thumb is that if planting is delayed until May 10-15, the yield loss is 1 bushel per day for each day delayed. If planting is delayed until May 15-20, the yield loss is 1.5 bushels per day for each day delayed. If planting is delayed until May 20-30, the yield loss is 2 bushels per day for each day that planting is delayed.