Using drought-stressed corn for forage

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Drought-stressed corn is prevalent in many areas of the state. Much of this moisture stress occurred during the critical developmental stages of pollination and early grain fill. Moisture needs for corn are high in these stages, and severe moisture stress during this time can have a significant impact on grain yield and quality. In situations where pollination success was marginal or kernel development is poor, grain producers may be looking at using drought-stressed corn for forage. Before harvesting the crop for forage, ensure that any pesticides used (including any herbicides, insecticides, or fungicides applied) allow utilization as forage and that any pre-harvest intervals are met. For example, if atrazine was applied to corn, label restrictions state to “not harvest corn for forage within 60 days of application.” Be sure to check with your crop insurance provider before harvesting the crop for forage, or your local FSA office for non-insured crops (i.e. blue corn). Also, be aware of the potential for high nitrate levels in the forage, and use recommended precautions in handling the forage before feeding it to livestock. Nitrates can accumulate in drought-stressed corn, particularly if stalks are barren. The lower one-third of the stalk typically contains the highest amount of nitrate accumulation. Dale Hicks and Paul Peterson, University of Minnesota Extension, report that the occurrence of drought during or immediately after pollination could be associated with highest nitrate accumulations.  Ensiling drought-stressed corn is preferred over chopping or grazing, since ensiling can reduce forage nitrate levels. Be aware that although the crop may look dry, barren stalks may still contain 70 to 90 percent moisture. Target a harvest moisture of 60 to 70 percent for proper storage, which is the range normally targeted for corn silage. Safety precautions are also a must when ensiling drought-stressed corn since nitrous oxide, which is toxic to humans and livestock, is released in the ensiling process. Forage testing is recommended prior to feeding to determine if there are any quality problems, as well as to determine the nutritional value of the forage. If kernel growth is still occurring in the field, it will likely pay to wait with harvesting. This will allow for more grain fill, which will help increase forage yield and quality.    Liz Stahl and Douglas Holen are crops educators with University of Minnesota Extension Service.