By Jenna Falor and Kim Cassida
With corn silage harvest in full swing, livestock producers should be aware that prolonged moisture stress, high temperatures and low humidity during this year’s growing season may have led to elevated nitrate levels.
Nitrate accumulation is the major concern
Producers making plans to harvest corn silage due to drought damage should be aware of major issues associated with nitrate accumulation in the plants. This increase in nitrates is most significant following the late season rainfall events over Michigan. Corn that has received higher amounts of nitrogen fertilizer and manure application prior to drought conditions setting in, typically higher yield potential corn, will be more prone to excess nitrate in harvested corn silage.
As corn plants recover with those first rains after a drought, nitrates are taken up at levels greater than they can assimilate. This causes nitrate concentrations to spike in the plant to levels that can be toxic to livestock. This is especially important if farmers are feeding green-chopped corn or corn silage. To minimize risk, generally wait two weeks before harvesting the silage.
Ensiling corn silage will reduce the amount of nitrates in the plant materials by one-third to one-half during the ensiling process. However, even with corn silage stored in bunker silos for several weeks, it is impossible to accurately predict levels of nitrates in drought-stressed corn silage. Nitrate levels should always be tested before the silage is fed to make sure rations are balanced to stay below nitrate toxicity thresholds for the type of livestock.
Source : msu.edu