Considerations for Harvesting Drought-Stressed Corn
By Donna Amaral-Phillips, Jeff Lehmkuhler, and Chad Lee
Remember to consider:
- If corn is going to be fed as green chop, grazed, or as hay, test for nitrates before harvest to be sure the crop will be safe to feed. For corn harvested properly as silage or baleage and which goes through a good fermentation, nitrate levels could decrease 30 to 50% and can be tested after fermentation and before being fed. If you need to decide which corn fields to harvest as silage or hay, testing before harvesting will allow one to determine which fields need to be harvested as silage (those higher in nitrates) and those with safe levels of nitrates which can be harvested as corn hay. For sorghums and sorghum-sudangrasses, nitrates should be tested before harvest to be safe for your harvest method.
- Check herbicide withdrawals to make sure the crop can be fed to livestock.
- Raise the cut high—nitrates are highest in the plant stem closer to the ground. This may be more difficult if using a disc mower or other hay equipment for the purpose of making hay or baleage.
- If at all possible, harvest as silage and let ferment for 4-6 weeks before feeding. You may want to consider using a silage inoculant. Again, test for nitrates before feeding.
- Immature corn will be more variable in nutrient content than “normal corn silage”. After harvest, test the forage for its nutrient content and develop and feed a balanced ration to your cattle.
- Watch the moisture content of the crop closely. A small amount can be chopped to determine the current moisture content. Corn is drying down quickly in parts of KY. You will need to use a Koster tester or microwave to determine the actual moisture content. Silage and baleage need to be correct moisture to ferment properly and make good feed.
- Can you add enough water at the bagger or silo blower to increase the moisture content of the silage? For each 1% increase in moisture content, approximately 7 gallons of water is needed per ton. A typical garden hose delivers approximately 8-10 gallons per minute. Thus, it is nearly impossible to deliver enough water to make a difference. For example, to increase the moisture content from 45% moisture (55% dry matter) to 60% moisture (40% dry matter) for a wagon load of silage (4 ton capacity), you need to add 420 gallons of water-- Not feasible!!
Can you make baleage out of corn? Yes- but moisture and other harvesting techniques are important.
- Moisture content needs to be between 45 to 60%. Getting the crop at the moisture content can be very challenging.
- Material needs to be crimped and/or conditioned before baling. Conditioning is a must to get the crop to ferment. Using a rotary mower (i.e. bushhog) may also work but make sure the blades are sharp to reduce shredding of the corn plant. If your baler has knives, they can be used to chop the corn plant.
- Newer balers work the best. This is a very coarse crop that is tough on hay equipment and some older style balers may have difficulty handling the crop.
- Inoculate can be added at the baler, if you are equipped to handle this.
- Wrap with at least 2 extra layers of plastic for a total of 7 layers of plastic due to corn stalks puncturing the plastic.
- Net wrap may work better than string tie balers. If you use a string tie baler, additional wraps of string should be used.
Can you make hay out of the crop? YES--- BUT
- Nitrates will not decrease from the standing crop. The crop needs to undergo normal fermentation to decrease the level of nitrates. Hay does not ferment!!! If they are high in the standing crop, they will not decrease with harvest and storage.
- Moisture needs to be about 15%. If the crop is harvested with over 18% moisture, it will heat and make a very poor feed. It can spontaneously combust if too wet and goes through a heat.
- Corn stalks can be very variable in nutrient content (protein and energy) and may require supplementation depending on the cattle being fed.
Please see the UK webpage http://www.uky.edu/Ag/GrainCrops/Briefs/nitrate_testing2012.html for more information on nitrate issues.