Some Pros and Cons of Letting Corn Stand in the Field Through Winter

October 15, 2004 11(26):170-171

Joe Lauer, Corn Agronomist

Due to late corn planting dates, some farmers are considering leaving their corn in the field through winter and harvesting in the spring. Delayed planting combined with below normal heat units for the 2004 growing season has resulted in a crop that is behind normal development. As of September 19, only 43% of the corn in Wisconsin was dented making the corn crop more vulnerable to early frost damage before it reaches physiological maturity. Even if it's not damaged by frost, immature corn will exhibit higher moisture which will increase drying costs and lower test weight (weight per bushel at 15.5% moisture), a key indicator of quality in corn.

Every year some fields in Wisconsin are harvested in the spring. If the stalks stay standing and there isn't much ear drop, snow cover or wildlife damage; the crop can get through the winter without much yield loss. Ear drop will vary by hybrid and environmental conditions as well as the amount of grain on the ear (smaller ears should stay attached better than larger ears). If winter conditions are cool without snow then corn will continue to dry and can be harvested throughout the winter without too much yield loss. Stalks will become brittle and broken corn parts may decrease the grade causing discounts at the elevator.

Since we cannot predict the weather, the most prudent decision would be to harvest after a reasonable period of drydown. In some years with heavy snow cover, grain yield can decrease significantly (Table 1). For example, during 2000 grain yield decreased 65% by March and by spring yield decreased 37% from an October harvest date. This is contrasted with the winter following 2001 (little snow cover) when yield only decreased 18% by February and by spring was 10% lower than October harvest.

Greatest grain moisture loss occurs during October and November (Table 2). Drying continues through the winter, but at a slower rate than October and November. This is especially true for later planting dates. By the following spring there is little difference in grain moisture for early versus later planted fields. Grain test weight changes are minimal regardless of planting date (Table 3). Since grain moisture changes are minimal past December and grain yield losses can be significantly affected by environment, the best decision is to complete harvest by December (or the typical first heavy snowfall, if you are good at predicting such things).

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

Table 2. Grain moisture (%) change of corn left standing in the field through winter. Data are summarized for the 1992, 1993, 1994, 2000, and 2001 production seasons at Arlington, WI.
Planting Harvest month
dates Oct Nov Dec Jan Feb Mar Apr
before May 11 31 21 20 19 18 15 12
May 11 to May 31 37 27 22 22 18 16 10
after May 31 46 37 28 27 23 20 15

Table 3. Grain test weight (lb/bu) change of corn left standing in the field through winter. Data are summarized for the 1992, 1993, and 1994 production seasons at Arlington, WI.
Planting Harvest month
dates Oct Nov Dec Jan Feb Mar Apr
before May 11 58 55 54 55 54 55 56
May 11 to May 31 57 50 52 51 53 50 52
after May 31 51 44 46 46 46 47 48

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