Managing Challenging Harvest Conditions

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KEY POINTS

  • Scouting fields prior to harvest can help determine problems and harvest order.
  • Proper combine setup for the grain condition is important.
  • Checking grain moisture in each load and throughout the storage period can help prevent spoilage.
  • Fall tillage may be needed to fill ruts and address soil compaction issues.

Challenging conditions can occur at harvest. Soils can be wet or the crop may be delayed or drying down slowly and you need to decide whether to leave the crop in the field to dry down or harvest the crop at higher moisture than you’d like. Some things to consider include: the cost of drying grain for storage, risks associated with leaving the crop in the field to dry down, combine adjustments to harvest high moisture crops, reduced grain quality and storability, dealing with soil compaction, and managing variable moisture grain in the storage bin.

Pre-harvest field scouting can help determine crop maturity, stalk and root quality, or identify stalk and ear rots. Check roots for rootworm damage, use a pinch/push test to estimate stalk quality, and check ears for insect damage and mold. Based on these evaluations and the weather forecast, a harvest plan can be developed to get the most compromised grain out of the field first and help manage potential storage problems.

Delayed maturity of corn (late planting, cool growing season, or wet soil conditions) can translate into slow drydown of mature corn grain. Temperature and humidity influence the rate of drydown, which declines quickly in late September and October. Wetter grain at harvest increases the need for artificial drying of grain and increased production costs.


Harvest

The risk of lodging, stalk and ear diseases, or reduced grain quality increases the longer corn is in the field. Higher grain moisture and ear rot damage can increase the amount of fine materials in the bin which can interfere with aeration or be a source of disease, mold, or toxins associated with ear rot.

The most important factor in handling high moisture corn at harvest is proper adjustments to combines:

  • Proper combine adjustments can help harvest corn between 20-30% moisture.
  • Adequate ground speed is needed to keep the separator and cleaning shoe at full speed.
  • Keep the corn head high to reduce wet material from entering the combine and maintain the combine’s ability to thresh and separate grain.
  • Level the concave from side-to-side before changing the concave clearance for uniform adjustments.

Check the manufacturer’s recommendation for additional adjustments on harvesting wet crops.

Adjust equipment to minimize the degradation of wet grain quality:

  • Combine settings. Balance the need for aggressive shelling action to get small kernels off the cob against the extra kernel damage that is caused by aggressive shelling. Balance the need for aggressive cleaning to remove chaff and small particles against yield losses that occur when small, light kernels are blown out of the combine.
  • Manage fines and chaff. Fine particles and chaff affect airflow movement and increase mold problems in storage. Consider cleaning grain to remove fines and chaff, “core” bins to pull fines out of the center, or make sure that fines and chaff are uniformly distributed throughout the storage bin rather than being concentrated in certain areas.
  • Dry grain uniformly. Check grain moisture content of every load of corn and reset dryer controls based on changing moisture levels. Make sure that the moisture content of dried corn is low enough for safe storage (15% for winter storage, 14% for storage into spring and summer, 13% for a year or more storage time) and consider reducing these moisture levels by about a percentage point for corn that is immature, frost damaged, or low test weight.
  • Dry corn gently. High drying temperatures can result in lower test weight and in more cracked and broken kernels. Natural-air drying (no heat) gives better test weight and less kernel damage than gas-fired drying. Use slow cooling methods after gas-fired drying to minimize quality problems.
  • Aerate stored grain to 20-30°F for winter storage.
  • Check stored grain frequently so that you can quickly address minor spoilage problems before they become big, costly problems.
  • Moldy grain can have a shorter storage life than clean grain. Don’t mix new with old grain
  • Temporary grain piles should be at commercial facilities not on farm sites. Small piles tend to spoil more rapidly than large piles and large piles are easier to aerate.

To keep wet grain going into storage from heating and losing quality, run the aeration fan continuously whenever grain exceeds 18% moisture and grain temperature is above 50°F. The length of time corn can be kept under constant temperature and moisture content before it losses 1/2% dry matter (the maximum loss to maintain current market grade) is shown in Table 1. General rules of thumb for corn above 16% moisture are shelf life is half as long at given temperature for every 2 points of moisture greater than 16% and shelf life is half as long for every 10°F increase in temperature. Soybeans in storage have a shelf life similar to corn that is 2% greater in moisture content (Table 1).

Harvest traffic on wet soils can cause ruts and soil compaction. Ruts left in the field can create an uneven soil surface and affects seed soil contact during planting. Managing traffic patterns in fields can help minimize the detrimental effects of ruts and surface soil compaction. Traffic pattern management usually involves uniform machinery sizing and use of global positioning system (GPS) guidance of equipment. Some guidance for managing soil compaction during a wet harvest include:

  • Use surface or shallow tillage to reduce ruts in the field.
  • Reduce equipment tire pressure and axel loads.
  • Maintain repeated travel patterns to help contain and reduce soil damage.
  • Use a cover crop and rely on the freeze/thaw conditions in winter to address shallow compaction. Subsoiling may be necessary if compaction is deeper than 6 inches in the soil
  • To help spread overall pressure on the soil, use tracks, low tire pressure, or dual wheels on equipment and consider reducing load size in equipment transporting grain out of the field.