Agronomy Degree Practice Exam

Which nutrient is predominantly supplied by urea fertilizer?

1. Phosphorus

2. Potassium

3. Nitrogen

4. Calcium

The correct answer is: Nitrogen

Urea fertilizer is primarily known for its high nitrogen content, which is a critical nutrient for plant growth. Nitrogen plays a vital role in forming amino acids, the building blocks of proteins, and is essential for the synthesis of chlorophyll, which plants use for photosynthesis. When applied to the soil, urea is converted by soil microorganisms into ammonium and then into nitrate, both of which are readily taken up by plants. Urea contains approximately 46% nitrogen by weight, making it one of the most concentrated nitrogen sources available, which is why it is widely used in agriculture to promote vegetative growth and improve crop yields. The process of nitrogen assimilation in plants is crucial for their development, influencing growth patterns, leaf production, and overall health. In contrast, phosphorus, potassium, and calcium are also essential nutrients but are supplied by different fertilizers formulated specifically for those nutrients. Phosphorus supports root development and flowering, potassium regulates water use and enzyme activation, and calcium is important for cell wall structure and growth. Each of these nutrients plays unique roles in plant physiology but are not predominantly supplied by urea.