Snow Effects on Corn and Soybean Harvest

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KEY POINTS

  • Early snowfall can hamper crop harvesting and can result in considerable yield loss.
  • Depending on the amount of snow, air temperature, and additional moisture in the form of snow or rain, harvest may be delayed until the ground is frozen or next spring.
  • Snowy fields can increase grain moisture content and be tough on harvesting equipment.

What to Watch For

The combination of late planting, abundant fall rain, and early snow can delay corn (Zea mays) and soybean (Glycine max) harvesting (Figure 1). Additionally, blanketing snow can reduce or prevent the soil from freezing to depths that can hold up harvesting equipment. With these conditions, harvest could be delayed until spring.


Snow Harvest

Figure 1. Corn and soybean plants blanketed in snow.


Effect on Your Crop

The amount of potential yield loss for corn can be dependent on plant populations, stalk lodging, ear drop, ear size, grain quality, wildlife damage, and additional rain or snowfall amounts.

A Wisconsin study (Table 1) shows the average percent loss in corn yield for the years 2000 and 2001 when corn was left in the field throughout the winter and harvested monthly through April.1 Lodging in 2000 increased the percent of lost yield compared to 2001.1


Snow Harvest

Corn kernels can become subject to sprouting during early-spring time melting before field conditions allow for harvest. Very little yield loss information is available for soybean fields left through the winter; however, the potential for yield loss is likely to increase. Heavy snow can cause soybean plants to lodge or break off and become difficult to harvest.

During melting cycles, pods can become wet and break open when seeds enlarge because of increased moisture content. Exposed seeds can drop to the ground, lose quality, or become food for foraging wildlife. High plant populations and soybean products with marginal standability characteristics may have a negative impact on winter-time standability. Additionally, as harvest is delayed, the opportunity for Diaporthe (pod and stem blight) increases.

Management Tips

The cost of drying harvestable wet corn in late-fall or early-winter should be compared to the breakeven cost of leaving corn in the field through winter. If the drying bill is less than the estimated yield loss from lodging, ear drop, disease, and wildlife, then fall harvesting if at possible should be accomplished.

Table 2 provides a total drying charge compared to a 5% to 40% winter yield loss at grain prices ranging from $3.00 to $4.25 per bushel.1 A higher corn price justifies increased drying costs while lower prices can decrease justification and increase the opportunity to leave corn in the field and harvest as weather and conditions permit throughout the winter.


Snow Harvest

Factors to weigh prior to harvesting a delayed harvest field:

  • Can the field support harvesting equipment without causing compaction or huge ruts?
  • Combines may be able to thresh wet or frozen corn; however, the combination of plant moisture and air temperatures (between 27° F and 35° F) can create an evaporative cooling effect and create grain cleaning problems. If plants are covered with snow or wet with moisture, the air temperature should be observed.
  • Standability should be considered - what is the stalk strength? Lodged corn that is dry may feed through the combine easier. Lodged soybean plants become difficult to pick up and sickle bars running close to the ground can be damaged.
  • What is your storage and drying situation for wet grain? Soybean moisture content should be below 20% for harvesting without causing seed damage.2
  • Potential for volunteer corn in the following crop.
  • If the crop is left through the winter, will other spring-time field activities be delayed?
  • Potential damage to equipment if harvesting through snow and wet fields.

Sources: 1Schneider, N. and Lauer, J. 2009. Weigh risk of leaving corn stand through winter. University of Wisconsin. http://corn.agronomy.wisc.edu/ 2Staton, M. 2017. Recommendations for a late soybean harvest. Michigan State University. http://www.canr.msu.edu/ Additional source: Jasa, P. 2010. Combine recommendations for spring harvest. CropWatch. University of Nebraska. https://cropwatch.unl.edu Web sources verified 10/17/18.