Certified Professional Horticulturist (CPH) Practice Exam

The best type of fertilizer for slow-release application is urea form. This type refers specifically to fertilizers that incorporate urea in a stabilized form, which allows for the gradual release of nitrogen over an extended period. This slow-release mechanism benefits plant growth by providing a steady supply of nutrients, reducing the risk of nutrient leaching and minimizing the frequency of application.

Urea, while a common nitrogen source, can release its nitrogen quickly if not applied correctly or if environmental conditions are favorable for rapid breakdown. Ammonium nitrate and ammonium sulfate, on the other hand, are more soluble and available forms of nitrogen that tend to be utilized by plants quickly, leading to a fast release rather than a controlled, gradual supply. This makes them less suitable for situations where slow-release characteristics are desired.

Using the urea form ensures that plants can access nitrogen as needed over time, which supports their growth and health, making it the preferred choice for slow-release applications.