Weigh Risk of Leaving Corn Stand Through Winter

Nick Schneider, Winnebago County Agriculture Agent        
Joe Lauer, UW Corn Agronomist

The October 26, 2009 Wisconsin Crop Progress Report from the Wisconsin Field Office of the National Agriculture Statistics Service stated only 9% of the Wisconsin corn crop has been harvested, far less than the 5-year average of 37%.  Moisture spot checks are indicating very wet grain with unfavorable drying weather in the near-term forecast.  Even if grain moisture was dry enough for harvest, saturated soils will likely cause further delays.  This situation has caused some corn growers to consider leaving corn stand in the field until spring.  Lauer (2004) examined the amount of yield loss during winter months at the University of Wisconsin Arlington Research Station in 2000-2001 (Table 1).   

Table 1. Grain yield (bu/A) change of corn left standing in the field through winter at Arlington, WI.
	Harvest Month
Year	Oct	Nov	Dec	Jan	Feb	Mar	Apr
2000	204	206	113	86	83	72	127
2001	220	208	208	200	181	205	199
Mean	212	206	165	145	134	145	162

   Many factors influence the decision to harvest yet this fall or delay until spring.  Some factors can be assessed now, such as stalk strength, ear health, insect damage, and shank attachment.  A crop that has weak plant integrity now is at greatest risk of crop losses if harvest is delayed.  Fields with good stalk strength and a soundly attached ear might be good candidate fields for delaying harvest; however, crop health only has one direction to go…down.  Beyond plant integrity, factors such as wildlife damage and weather will play a major role in ear retention the following spring.  For example, in 2000, a year with heavy snow cover, the percentage yield loss was much greater than in 2001, a year with little snow cover (Table 2).

   If a corn grower is seriously considering leaving corn stand through winter, the most important question that needs to be answered is, “Will the revenue lost by winter crop damage be less than the cost of drying this fall?”  If the value of corn loss over winter from ear drop, fungus, or animal feeding is more than the drying bill would have been if harvested this fall, then it doesn’t make sense to leave corn stand until spring.  Table 3 identifies the breakeven point for total drying cost per bushel the grower would want to pay this fall compared to harvesting in spring.  The table provides a total drying cost compared to a 5% to 40% winter yield loss at prices ranging from $3.00 to $4.25 per bushel.  As corn price increases, the producer can tolerate paying a greater price for drying.  Additionally, as the percentage of yield loss through winter increases, the producer also can justify paying a greater drying cost.  For example, if this winter has heavy snowfall, similar to 2000, with a 38% yield loss by April harvest, the producer would be able to pay just over $1.31 /bu for drying corn worth $3.75 /bu (2009 price) to generate the same amount of revenue.  If conditions are more like the winter of 2001 with only a 10% yield loss and a price of $3.75 /bu, then the grower keeps more revenue by letting the corn stand in the field if drying costs are more than $0.38 /bu.   If in an average year 25% of corn yield is lost over winter, at $3.75 /bu, the grower can pay up to $0.94 /bu for drying and breakeven with field loss.  For growers that view field drying as a secondary form of storage; thereby reducing storage fees, then the total of drying and storage costs should be combined and compared to the percent yield loss through winter.