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5. Use Nitrification Inhibitors When Effective

Nitrification process

Plants can use both the ammonium and nitrate forms of nitrogen. But the nitrate form is more susceptible to leaching. It poses more risk to groundwater.

Nitrification is a process in which bacteria convert ammonium forms of nitrogen into nitrate forms. Nitrification inhibitors are chemicals designed to slow this process, reducing the risk that nitrogen will be lost through leaching and denitrification. (With denitrification, soil organisms convert nitrate-nitrogen into a form that is unavailable to the plants. )
Inhibitors are most useful ...

Inhibitors are most useful in the following situations:

  • When the soil is moderately or well-drained and is in an area of heavy rainfall or frequent flooding.
  • When you apply nitrogen in the fall, ammonium forms of N have more time to convert into nitrate forms. Inhibitors reduce this risk.
applying nitrogen If you apply nitrogen with inhibitors in the fall, make applications after the soil temperature has dropped below 60 degrees F and the soil is likely to be frozen for most of the winter.
applying nitrogen Inhibitors work best when nitrogen is applied at or below optimum levels. They are not necessary if you put down nitrogen right before the crop needs it or as a sidedressing application.
application of nitrogen Inhibitors do not work as well in extremely coarse soils, unless nitrogen applications are managed carefully. In coarse soils, ammonium nitrogen has a tendency to move away from the inhibitors.
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