Certified Arborist Practice Exam

What is a complete fertilizer typically composed of?

1. Dissolved in water

2. Injected below the absorbing roots

3. Wilting, marginal burning, dieback

4. Nitrogen, phosphorus, and potassium

The correct answer is: Nitrogen, phosphorus, and potassium

A complete fertilizer is typically composed of nitrogen, phosphorus, and potassium, often referred to as the "N-P-K" ratio. These three nutrients are essential for plant growth and development. Nitrogen promotes leafy, vegetative growth; phosphorus contributes to root development and flowering; and potassium is important for overall plant health and resilience against disease. While the other options reference different aspects of plant health and nutrient application, they do not pertain to the composition of a complete fertilizer. For example, dissolved in water can describe how some fertilizers are applied but does not define a complete fertilizer. Injecting a fertilizer below the absorbing roots is a method of application rather than its composition. Meanwhile, the symptoms mentioned—wilting, marginal burning, and dieback—relate to plant stress or nutrient deficiencies but do not provide information about what constitutes a complete fertilizer. Understanding the key components of a complete fertilizer is crucial for effective plant care and can help in diagnosing potential growth issues related to nutrient deficiencies.