March 5, 2010

With the cool, wet conditions last fall, many producers waited for corn to dry in the field before harvest. With the early and continued snows, some fields still haven’t been harvested. In some areas about 5% of the corn crop is still standing in the field. Some producers may only have the north and west 10 to 20 rows left to harvest due to drifted snow.

Factors to Consider When deciding when to head to the field to finish harvest, consider several factors: Is the soil frozen or firm enough to drive on? If thawed, what is the soil moisture and potential for tearing up the fields? If there is snow or moisture on the plants, what is the air temperature? Is the corn downed or will more go down if you wait? How much additional field losses will occur if you wait? Are there other options, such as grazing? Is the corn dry or do you have some place to go with wet corn? Will waiting cause delays with field operations for the next crop? How can you process the residue to minimize problems for the next crop? Are there insurance or crop loss payments or issues?

As temperatures warm and breezes blow, the grain will continue drying in the field. As the snow melts, some producers are heading to the field to finish their corn harvest and reporting grain moisture contents around 16%. Some are harvesting up to the deep drifts and turning around. (It is best to operate the cornhead above the snow on the ground to reduce wear and potential damage to the head.) Other producers are waiting for the deep drifts to melt and hope to be able to harvest the corn in late March or early April before the spring rains start.

Usually the ground freezes in winter, up to several feet deep, and fields should be firm enough to harvest before the spring thaw. However, in some areas of the state, the snow came before the ground was frozen very deep. With the insulating snow cover, some frozen soils thawed out from the warmth coming up from below. This, combined with the moisture from the melting snow, is making some fields very muddy and difficult to harvest. Once the snow cover melts away, the soil surface should firm up as long as the nighttime temperatures stay below freezing. After the remaining frost goes out of the ground, the soils should firm up as the fields dry.

Spring Harvest Recommendations

If you’re planning to head to the field this month with your combine, take stock of the air temperature. This is particularly important if there is any snow still on the stalks and ears or if the ears have water or snow inside the husks. While a combine can thresh wet or frozen corn, the moisture can create some problems with cleaning.

If there is snow on the stalks and ears and the air temperature is below 25ºF, any snow should just pass through the combine. Above 27ºF or so, the friction of the threshing operation warms the materials passing through the combine, melting the snow. The evaporative cooling effect of the fan blowing cold air across the sieves to clean the grain freezes that moisture and some of the corn on the cleaning system, blocking airflow. Even if there is no snow on the plants, this may be a problem if there is free water on the ears inside the husks. If the air temperature is above 35ºF, the fan shouldn't cause the moisture to freeze.

Some of the snow has caused areas of downed corn, particularly on the north and west 10 to 20 rows in the field. For now, many of those areas still have considerable drifts. In approaching harvest, producers may want to give first priority to the standing corn and then harvest any downed corn. (It’s amazing how much of the corn in the field is still standing.) If downed corn is a problem, waiting until the snow is gone and the stalks are dry will reduce feeding problems into the combine.
 

For a nice roundup of tips for harvesting downed corn, see this Ohio State University Web article.

Paul Jasa
Extension Engineer