To minimize nitrogen volatilization when applying granular fertilizer, which practice is recommended?

• A. Apply during dry, hot conditions
• B. Leave dry soil for several days after application
• C. Water in the fertilizer soon after application or irrigate to moisture after application
• D. Apply only at night with no wind

Answer: (C)

The key idea is that keeping the fertilizer moisture around the granules reduces nitrogen losses from volatilization. When granular nitrogen, especially urea-based products, sits on a dry surface, ammonia can escape as gas, wasting fertilizer. Watering in soon after application—or irrigating to bring soil to moisture—dissolves the granules, promotes conversion of nitrogen to forms that stay in the soil (like ammonium), and keeps ammonia from volatilizing. This makes more nitrogen available to plant roots.

Applying in dry, hot conditions or leaving the soil dry after application creates conditions that favor volatilization, so more nitrogen is lost before plants can use it. Applying only at night with no wind might help reduce surface evaporation, but without moisture around the granules it won’t reliably prevent volatilization. Watering in after application is the most effective method to minimize these losses.