CH Plant Nutrition and Fertilization

Question 1

Which macronutrient is most often responsible for the yellowing of older leaves (chlorosis) in nitrogen-deficient plants?

Accepted Answer

Nitrogen

Answer

Nitrogen is a mobile nutrient that moves from older leaves to younger growth, causing older leaves to yellow first when deficient.

Question 2

A fertilizer labeled 10-10-10 contains equal percentages of which three primary nutrients?

Accepted Answer

Nitrogen, Phosphorus, Potassium

Answer

The three numbers on a fertilizer label (N-P-K) represent the percentage by weight of nitrogen, phosphorus (as P2O5), and potassium (as K2O).

Question 3

Which soil pH range generally maximizes nutrient availability for most landscape plants?

Accepted Answer

5.5–6.5

Answer

A pH of 5.5–6.5 keeps most macro- and micronutrients in plant-available forms and is the optimum range for the majority of landscape species.

Question 4

Iron deficiency interveinal chlorosis on young leaves is most commonly caused by which soil condition?

Accepted Answer

High soil pH

Answer

High soil pH (alkaline conditions) causes iron to precipitate into unavailable forms, resulting in interveinal chlorosis on new leaves.

Question 5

Slow-release fertilizers benefit landscape plants primarily because they:

Accepted Answer

Reduce leaching and provide sustained nutrition

Answer

Slow-release fertilizers break down gradually, reducing nutrient leaching and providing a steady supply of nutrients over weeks or months.

CH - Certified Horticulturist Practice Test