Which practice reduces nitrate content in stored forages?

• A. Drying in sun
• B. Harvest before flowering
• C. Ensiling (anaerobic fermentation reduces nitrate to nitrite)
• D. Applying nitrate-based fertilizer

Answer: (C)

Ensiling reduces nitrate content because the anaerobic fermentation environment drives microbial transformations that convert nitrates into nitrite and then into ammonia. When forage is packed tightly for silage, lactic acid bacteria thrive and produce lactic acid, lowering the pH and creating oxygen-free conditions. In this acidic, anaerobic setting, bacteria use nitrate as an electron acceptor, first reducing it to nitrite, and then further reducing nitrite to ammonium. This sequence lowers the nitrate pool available in the stored forage, decreasing potential nitrate exposure to ruminants. Nitrite can appear transiently, but the overall nitrate content declines with proper ensiling.

Drying in the sun is an aerobic process and does not reliably decrease nitrate levels in stored forage. Harvesting before flowering and applying nitrate-based fertilizer tend to maintain or increase nitrate content rather than reduce it, so they aren’t effective for lowering nitrates.