Certified Crop Advisor Practice Exam

Which loss pathway is most concerning for the loss of nitrate nitrogen?

1. Erosion

2. Leaching

3. Volatilization

4. Runoff

The correct answer is: Leaching

Nitrate nitrogen is highly soluble in water, making leaching a significant concern for its loss from agricultural soils. When rainwater or irrigation occurs, the nitrate can easily move through the soil profile beyond the root zone, leading to a reduction in the availability of this essential nutrient for crops. This process can result in environmental issues, particularly when leached nitrates enter groundwater supplies and potentially contaminate drinking water. In contrast, while erosion can lead to the loss of some nutrients, it primarily affects soil particles rather than soluble forms like nitrates. Volatilization pertains more to nitrogen in the form of ammonia rather than nitrate, as this process involves the conversion of ammonium into gas under specific conditions. Runoff can transport both particulate and dissolved nutrients, but it is less critical for nitrate nitrogen compared to leaching, as it is the direct movement of nitrates through the soil that predominantly causes their loss in easily accessible forms. Therefore, among the various pathways, leaching presents the most significant risk for nitrate nitrogen loss.