Despite the calendar, freezing temperatures have generally stayed well north of the Cornbelt. However, crop-killing temperatures are now in the western sections of the Dakotas, and expected into Nebraska beginning this weekend. While weather services do not indicate colder than normal temperatures for the next two weeks, farmers with immature crops may want to determine whether they will be put in a bin or silo.

Late planted corn, either fields or ponds, may still be in the milk stage and far from maturity. Iowa State agronomists Stephen Barnhart and Roger Elmore suggest that farmers determine how their corn crop will develop by normal frost time. Even if it is harvested wet and has to be dried, it will be more valuable as grain than as silage. If the crop is to be harvested as silage, the optimum harvest time will be several days before plant maturity when nutrients are at their peak. So the key is to know just how mature the crop is.

1) The milk line moves from the dent to the point of the kernel, and when it reaches that point, the black layer forms indicating no further kernel development and the start of drydown.
2) When the milk line has traveled two-thirds of its route, the corn plant has the highest value as silage, in terms of moisture, total digestible nutrients, and dry matter yield.
3) If frost occurs during the target milk line period, whole plant moisture content should be appropriate for ensiling.
4) If there is too much milk in the kernel when chopped for silage, moisture will be too high and fermentation will be incomplete. The Iowa State specialists recommend having a lab test the moisture in a sample of immature corn.

Soybeans can similarly be harvested as silage, if frost kills the plant and the beans fail to mature normally. Iowa State agronomists Stephen Barnhart and Palle Pederson say soybeans should be in the R-5 stage or later by now, but if only at R-5, a killing frost will reduce the yield by 75% and cause quality problems that will result in substantial dockage if harvested as grain. Beans must reach an R-6 stage to escape that problem, but are not really mature until R-7 when pods at the top of the plant are brown and pods are multicolored through the rest of the bean plant.

The agronomists say the decision to harvest as grain or forage is if the transition has been made from R-5 to R-6. If the shift has not been made, then the R-5 bean plant is better off as silage. They say at that stage the plant is similar in feed value to alfalfa or red clover. The leaves and pods will be digestible, but the stem will be less digestible. Beyond the R-6 stage, leaf value will be lost.

If the soybeans are being treated as dry hay, the stems will take longer to dry; and leaves will become brittle and be lost in the field. A conditioner can help with the drying, but a flail conditioner will create more leaf loss. Frost will cause leaves to die and drop quickly. If the beans are baled, inside storage is recommended because there will be high nutrient content lost outside.

If the beans are harvested as silage, the target moisture content is 60-65%, so drying time has to be carefully monitored. Dry soybeans will be difficult to pack, and wet soybeans will undergo abnormal fermentation. And the agronomists warn that before soybeans are used for forage, herbicide labels should be checked to determine the appropriate feeding limitations.

Summary:
Late maturing crops may soon clash with frost, leaving decisions on whether to harvest corn and soybeans as grain or as silage. The decision on corn is the maturity of the kernel, and if mature, it can be dried in bins. If the corn is still immature and milky, then the plant may have optimum nutrient content for silage. Soybeans can also be ensiled, or baled as hay, depending on whether the bean plant has made the transition from the R-5 to R-6 stage.