Certified Crop Advisor Practice Exam

What conditions favor volatile losses of nitrogen?

1. Low humidity

2. High temperature

3. Wet conditions

4. Cold temperature

The correct answer is: High temperature

Volatile losses of nitrogen, specifically through ammonia volatilization, are primarily favored by high temperatures. When temperatures increase, the rate of ammonia gas formation from nitrogen sources such as urea or manure also increases. This is because higher heat can enhance the breakdown of these nitrogen-containing compounds and promote the conversion of ammonia from the soil or surface applications into a gaseous phase that can escape into the atmosphere. In contrast, low humidity can actually reduce volatilization losses, as moisture helps to keep ammonia in the soil solution. Wet conditions tend to minimize losses by promoting the uptake of nitrogen by plants or the formation of stable ammonium forms that are less prone to volatilization. Cold temperatures can inhibit the microbial activity necessary for the conversion processes that lead to higher ammonia volatilization. Therefore, the condition that most significantly encourages volatile losses of nitrogen is indeed high temperature.