FFA Horticulture CDE General Practice Exam

What do the three numbers in a 10-10-10 fertilizer represent?

1. Hydrogen, nitrogen, and potassium

2. Nitrogen, phosphorus, and potassium

3. Calcium, magnesium, and sulfur

4. Phosphorus, potassium, and iron

The correct answer is: Nitrogen, phosphorus, and potassium

The three numbers in a fertilizer label like 10-10-10 represent the percentage by weight of the three primary nutrients it contains: nitrogen, phosphorus, and potassium, respectively. This specific sequence is standardized in the horticulture industry, making it easier for consumers to understand the nutrient composition of the fertilizer. In a 10-10-10 fertilizer, each of the numbers indicates that there is 10% nitrogen, 10% phosphorus (as P₂O₅), and 10% potassium (as K₂O) in the formulation. Nitrogen is essential for promoting leafy growth and overall plant vigor. Phosphorus supports root development, flowering, and fruiting, while potassium is crucial for overall plant health, aiding in processes such as water regulation and disease resistance. The other choices reference different elements and nutrient ratios that are not represented by the numbers in this context. For instance, hydrogen is typically part of water and not listed as a primary macro-nutrient on fertilizer labels, while calcium, magnesium, sulfur, iron, and their respective roles are important but are considered secondary macronutrients and micronutrients, not the primary trio indicated by those three numbers.