Nitrogen Credits for Manure & Legume Crops

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Agricultural Best Management Practices

Nitrogen Credits for Manure & Legume Crops

Nitrogen is an essential nutrient for corn, and fertilizer is only one nitrogen source. Other sources are irrigation water, soil, organic matter, previous bean or alfalfa crops, and manure. Farmers who take advantage of these other nitrogen sources often can apply less fertilizer.

Here’s how to calculate the amount of nitrogen corn can obtain from manure and previous crops of bean or alfalfa, based on University of Nebraska recommendations:

  • Manure: The amount of nitrogen released by manure spread on a field can vary a great deal, depending on the type of manure and soil conditions (mainly moisture and temperature). If possible, have a sample analyzed at a laboratory to determine nitrogen content. Otherwise, assume that beef cattle feedlot manure will supply 4 to 6 pounds of nitrogen per acre per ton of manure applied to the next crop, and about half that amount the second year.
  • Previous bean or alfalfa crops: Dry edible beans, alfalfa and other legumes fix nitrogen – that is, they take nitrogen from the atmosphere or soil and convert it to a form they can use. When these plants die, they release nitrogen back into the soil. A good stand of alfalfa should leave 80 to 120 pounds of nitrogen per acre to be used by the following crop. A 50-percent stand should provide from 40 to 60 pounds per acre. Dry edible beans will leave about 40 pounds of nitrogen per acre for the following year’s corn crop.

Additional Resources

For more details and information, contact the Cooperative Extension or USDA Natural Resources Conservation Service.

Online Resources

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