By SHELLY STRAUTZ-SPRINGBORN
Michigan Correspondent EAST LANSING, Mich. — Looks may be deceiving as farmers get a head start chopping corn silage this summer.
While parts of western and central Michigan have received heavy rains during the past few days, the moisture is too late to help most crops, including corn. Many corn fields already have sustained enough damage that the plants appear dry and brown – just right for silage harvest.
But, industry professionals are warning producers to take precautions to ensure that whole-plant moisture levels are adequate before they begin chopping silage. Corn that is too high in moisture levels when chopped may not ferment adequately, causing spoilage. Worse yet, high plant nitrate levels also could be a problem.
“The question comes up of when to harvest for silage corn that has gone through drought stress,” said Herb Bucholtz, Michigan State University professor of dairy nutrition and animal science. “The answer is no different than when trying to harvest normal corn for silage.”
Corn silage should be harvested when the whole-plant dry matter is between 30 and 35 percent. Dry matter content is important for the bacterial fermentation that takes place in the silage process.
“If it’s drier than that, you will not get as good fermentation, material will not store as well and may spoil and you may get a decrease in digestibility,” Bucholtz said.
Corn silage that is drier than 40 percent may not have enough sugars available for adequate fermentation, which typically results in heating up during feedout. It also is likely to be less digestible by cattle.
To test corn moisture levels, producers should select and chop 15-20 plants from various parts of the field.
They should test those plants using either a Koster moisture tester or a scale and a microwave oven.
Farmers should test often as harvest approaches, since the dry matter content of corn can decrease rapidly once the plant starts to dry down. Hot weather and winds can cause drought-stressed corn to dry down more rapidly than usual.
“The rate of dry-down on corn plants will differ from field to field, farm to farm and variety to variety,” Bucholtz said. “Producers have to monitor conditions for their individual farms – they can’t even count on doing what their neighbors are doing.”
Another area of concern for cattle farmers is the potential for high nitrate levels in drought-stressed corn, which can be toxic to cattle. Normally, corn plants process nitrates into harmless proteins.
However, drought-stressed plants don’t have enough moisture to carry out the conversion.
Experts recommend waiting two weeks after rainfall before harvesting drought-stressed corn or forage crops, to allow time for the recovering crops to convert the nitrates into usable proteins.
“Timing is everything,” said Ken Rauscher, director of the Michigan Department of Agriculture Pesticide and Plant Pest Management Division. “Delaying the harvest of drought-stressed corn, especially if the crop has been rained on, reduces the risk of nitrate toxicity to animals.”
Some sources suggest the lower one-third of the stalk may contain the highest concentration of nitrates, which may tempt some farmers to chop corn higher off the ground than normal to lower nitrate levels. MSU experts suggest, however, that chopping at the normal 4- to 6-inch level should be maintained to avoid unnecessarily losing yield.
Since nitrates are toxic to cattle, they also recommend not feeding cattle green-chopped corn plants and not to graze them or feed unfermented corn silage.
After the chopped material has undergone three to four weeks of fermentation, the nitrate levels should be reduced.Producers concerned about nitrate levels in their feed may submit samples for testing to at the MSU Plant Diagnostic Laboratory.
The cost is $12 per sample. Visit www.css.msu.edu/SoilTesting.cfm or call the lab at 517-355-0218 for more information. This farm news was published in the Aug. 29, 2007 issue of Farm World, serving Indiana, Ohio, Illinois, Kentucky, Michigan and Tennessee. |
