Well-Timed Harvest Can Maximize Yield Potential

KEY POINTS

  • Grain moisture content and stalk integrity can be used to help establish harvest order.
  • Combine settings can help increase combine efficiency, maximize grain quality, and minimize field losses.
  • Preventative measures and periodic inspections can help prevent grain from spoiling during storage.

Monitoring Grain Moisture

Grain moisture content should start to be monitored soon after physiological maturity (black layer). Aim for a harvest moisture content level that balances harvest losses and grain drying costs. A plan to take advantage of a rapid drydown and allow everything to field dry could be costly. Harvesting at lower moistures can increase mechanical losses due to ear drop, stalk lodging, and kernel shattering. Consider beginning harvest when corn grain moisture content is a little above 25% so that harvesting can be finished before corn dries completely in the field.1

With high temperatures, it is extremely easy to underestimate the rate that grain dries. Grain that matures in late August can have an average daily drydown rate of approximately 0.8 percentage point per day compared to 0.4 percentage point per day for grain nearing maturity in mid to late September.2

To test for grain moisture content, randomly select 10 ears, remove several rows of corn kernels from the full length of the ear, and mix the kernels thoroughly. Use a calibrated moisture meter to determine the moisture content. At least three moisture samples should be taken to determine an average moisture content.

Harvest Order

Existing and potential stalk and root lodging, disease pressure, and moisture content can affect harvest order. Stalk cannibalization and physiological stalk lodging can be due to nitrogen loss from excessive early season rainfall. Anthracnose top die-back and stalk rot can be prevalent in certain years. With excessive cannibalization and abundant stalk rots, fields need to be monitored closely to develop a harvest schedule that can help minimize lodging and harvest loss.

Scouting for Lodged Plants

The pinch and push tests are two methods to determine stalk integrity. The pinch test is conducted by squeezing the second or third internode above the ground. If it collapses, stalk quality is compromised. The push test is performed by pushing a corn stalk to approximately a 45 degree angle. If it breaks, stalk quality has been reduced. Conduct either test on 10 plants in a row and at several locations in the field. If more than 10% of the stalks tested show poor stalk quality, or lodge at the root, the field should be scheduled for early harvest.


Harvest

Figure 1. Achieving proper combine settings can help increase combine efficiency, maximize grain quality, and minimize field losses.

Harvesting Tips

In addition to harvesting at an optimum grain moisture content, achieving proper combine settings can help increase combine efficiency, maximize grain quality, and minimize field losses. Always follow the manufacturer’s equipment setting recommendations. Listed below are a few combine preparation tips:3

  • To minimize seed coat damage, start with the lowest manufacturer recommended cylinder speed setting. Only enough speed to adequately thresh the grain should be used while keeping losses to acceptable levels.
  • Airflow to clean grain is normally set at a higher level, and then reduced just below the point where the grain is blown out the rear of the cleaning shoe.
  • Deck plated/snapping rollers should be adjusted to match the size of ear and stalks. This can help avoid shelling on the ear and slipping through the front of the machine.
  • Spacing between plates should be 1.25 inches in a normal crop and ear savers (shields that keep ears from falling to the ground) should be maintained on the corn header.

Fields with considerable lodging should be harvested early to help minimize the risk of increased lodging and ear rots. Harvesting tips to help protect yield potential in fields with lodging include:

  • Consider using a corn reel if needed.
  • Harvesting against the angle of the lodged corn can help maximize lift into the header.
  • Time should be taken to make combine adjustments in the field.
  • Combines should be properly adjusted to minimize broken kernels and excess fines as they can lead to spoilage.
  • Over-threshing should be avoided.
  • Combines should be set to maximize the blow out of fines and foreign material.
  • Consult the combine operator’s manual for cylinder adjustments, speed and clearance settings suggested by the manufacturer.

Storage Tips

Stored corn should be checked frequently. Bins should be inspected every one to two weeks in the fall and spring, and once every two to four weeks after conditions in the bin have stabilized during the winter months. Preventative practices can be implemented to help protect corn from spoilage during storage:

  • Combines should be adjusted to minimize kernel damage and maximize cleaning.
  • Corn grain should be 13 to 14% moisture content prior to storage.
  • Grain should be stored at cool temperatures (35.6°F to 42.8°F) after drying.
  • Grain in storage should be checked periodically for temperature, hot spots, wet spots, and insects. Applying antifungal treatments to grain should be considered.