Understanding NPK Ratios and Fertilizers

This video tutorial explains the NPK ratio in fertilizers, focusing on nitrogen, phosphorus, and potassium. It provides detailed calculations for determining the percentage and weight of these nutrients in fertilizer packages. The tutorial includes examples to illustrate the process and addresses common misconceptions about NPK ratios.

Why is it important for horticulture students to understand NPK ratios?

• To reduce water usage

• To ensure proper nutrient supply

• To improve plant aesthetics

• To increase soil pH

What does the 'P' in the NPK ratio represent?

• Elemental phosphorus

• Phosphorus pentoxide

• Potassium

• Potassium oxide

In a fertilizer with an NPK ratio of 33-10-5, what percentage of the product is nitrogen?

• 33%

• 5%

• 50%

• 10%

How much phosphorus pentoxide is in a 40-pound bag with an NPK ratio of 33-10-5?

• 4 pounds

• 2 pounds

• 13.2 pounds

• 10 pounds

What is the molecular weight of phosphorus pentoxide (P2O5)?

• 78 grams per mole

• 142 grams per mole

• 62 grams per mole

• 94 grams per mole

What percentage of a P2O5 molecule is phosphorus?

• 44%

• 62%

• 83%

• 78%

In a 50-pound bag with an NPK ratio of 20-5-15, what is the percentage of filler?

• 40%

• 60%

• 20%

• 15%

How do you calculate the weight of nitrogen in a 50-pound bag with 20% nitrogen?

• Multiply 50 by 0.05

• Multiply 50 by 0.5

• Multiply 50 by 0.2

• Multiply 50 by 0.15

What is the percentage of elemental potassium in a fertilizer with 15% K2O?

• 15%

• 83%

• 12.45%

• 5%

What is the formula used to calculate the portion of a nutrient in a fertilizer?

• X times Y equals Z

• C times D equals E

• A times B equals C

• B times R equals P