Drought-stressed corn can still make some fairly good feed--if it’s harvested, ensiled and fed correctly. In fact, it can have up to 70% of the feed value of normal corn silage.
To ensure you’re harvesting the most forage you can, Bill Mahanna, nutrition sciences manager for DuPont Pioneer, offers these tips:
1. Don’t harvest too early. Even if the corn plant does not pollinate, it will continue to grow and add biomass—especially if it gets rain. "If little or no grain is present, a general rule is that there will be one ton of 70% moisture yield per foot of plant height," says Mahanna. Instead of 25 to 28 tons of silage, you may be looking at just five to eight tons per acre. So delay harvest as long as practical to achieve greater tonnages.
2. Check plant moisture prior to harvest. "Green, barren stalks will typically be much wetter than they appear in the field and can contain upwards of 75% to 90% moisture because there is no grain to dry down the moisture contained in the stalks," he says. So chop up a representative sample of plant material and use a microwave or Koster Moisture Tester to determine dry matter. For bunker silos, you’d like to have plant moisture at 68% to70%.
3. Test for nitrates. Drought-stressed corn is prone to higher levels of nitrates. Nevertheless, ensiling corn silage will quickly reduce nitrate levels. "Even at 2,000 parts per million, you can still feed up to half the total ration as corn silage and not run into problems," he says. So Mahanna recommends chopping plants at normal height to maximize tonnage. If you don’t use an inoculant, allow three weeks of fermentation before feeding. Note that field wilting and baling will not decrease nitrate levels.
4. Pack, pack, pack. Because there is little or no grain in the silage, drought-stressed corn silage will pack like grass silage or oatlage. The plants will also be high in yeast spores. Mahanna recommends the use of L. buchneri inoculant to inhibit yeast and mold growth and improve fiber digestibility.
5. Be aware of silo gas. Drought-stressed corn is high in nitrate and sugar, which in turn leads to the volatilization of nitrogen oxide, nitrogen dioxide and nitrogen tetraoxide. Exercise caution for at least three weeks after harvest—even in bunker silos because gases can accumulate near the ground. Dead rodents near bunkers and in silo rooms are a warning sign that silo gas is present.