Which nitrogen source is least likely to cause leaching or runoff in turf management?

Which nitrogen source is least likely to cause leaching or runoff in turf management?

• A. Slow-release nitrogen
• B. Urea
• C. Ammonium sulfate
• D. Calcium nitrate

Answer: (A)

The main idea is how the form and release rate of nitrogen affect its movement with water. In turf systems, nitrate is the mobile form and can move with percolating water or surface runoff, especially after rainfall or irrigation. A nitrogen source that releases nitrogen slowly over time tends to keep soil nitrogen levels lower at any given moment, so there’s less driving force for downward leaching or lateral runoff. Slow-release nitrogen provides a steady supply that better matches turf uptake, reducing spikes of soluble nitrogen in the root zone and the chances that water will carry it away. In contrast, rapidly soluble sources deliver nitrogen quickly, increasing the likelihood of nitrogen appearing in the soil solution after application. That makes leaching and runoff more probable during or after irrigation or rainfall. Even sources that feed directly into nitrate, like calcium nitrate, or those that furnish ammonium that later nitrifies to nitrate, can lead to higher losses if water movement is present. So the slow-release option is the best choice when aiming to minimize leaching or runoff in turf management.

The main idea is how the form and release rate of nitrogen affect its movement with water. In turf systems, nitrate is the mobile form and can move with percolating water or surface runoff, especially after rainfall or irrigation. A nitrogen source that releases nitrogen slowly over time tends to keep soil nitrogen levels lower at any given moment, so there’s less driving force for downward leaching or lateral runoff. Slow-release nitrogen provides a steady supply that better matches turf uptake, reducing spikes of soluble nitrogen in the root zone and the chances that water will carry it away.

In contrast, rapidly soluble sources deliver nitrogen quickly, increasing the likelihood of nitrogen appearing in the soil solution after application. That makes leaching and runoff more probable during or after irrigation or rainfall. Even sources that feed directly into nitrate, like calcium nitrate, or those that furnish ammonium that later nitrifies to nitrate, can lead to higher losses if water movement is present. So the slow-release option is the best choice when aiming to minimize leaching or runoff in turf management.