Fertilizer Calculation Worksheet
A Grade 9 science worksheet on calculating fertilizer application rates and understanding NPK ratios.
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Fertilizer Calculation Worksheet
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Read each question carefully and answer to the best of your ability. Show all your work for calculation questions.
Understanding NPK Ratios
Fertilizers are labeled with three numbers, representing the percentage by weight of Nitrogen (N), Phosphorus (P, as P2O5), and Potassium (K, as K2O). These are known as the NPK ratio.
1. The 'N' in NPK stands for , which is essential for plant growth.
2. The 'P' in NPK represents , important for root development and production.
3. The 'K' in NPK signifies , which helps with overall plant and disease resistance.
4. A fertilizer bag is labeled 10-20-10. What does the '20' represent?
20% Nitrogen
20% Phosphorus (P2O5)
20% Potassium (K2O)
20% inert ingredients
5. Which nutrient is primarily responsible for vigorous leaf and stem growth?
Nitrogen
Phosphorus
Potassium
Calcium
6. You have a 50 lb bag of fertilizer labeled 15-10-20. Calculate the following:
a) How many pounds of Nitrogen are in the bag?
b) How many pounds of Phosphorus (P2O5) are in the bag?
c) How many pounds of Potassium (K2O) are in the bag?
7. A farmer needs to apply 2 lbs of actual Nitrogen per 1000 sq ft. He has a fertilizer with an NPK ratio of 20-5-10. How many pounds of this fertilizer does he need to apply to a 5000 sq ft field?
8. The NPK ratio directly indicates the percentage of elemental P and K in the fertilizer.
True
False
9. A 'balanced' fertilizer would have an NPK ratio where all three numbers are similar, e.g., 10-10-10.
True
False