Remember:

a) A fertilizer contains nutrients plus other elements (often called carriers). The percentage nutrient can be calculated by knowing the weight of nutrient in the weight of fertilizer. This value is taken times 100 to get a percentage nutrient contained..
b) Regardless of the form of nutrient in fertilizer, the P is often expressed as P₂O₅ and the K as K₂O (oxide basis).
c) A fertilizer analysis is expressed as N-P₂O₅-K₂O where the nutrients are expressed as percentages.
d) The percentage of nutrient in a fertilizer = (lbs nutrient/lbs fertilizer) X 100.
e) The lbs of nutrients = lbs of fertilizer times % nutrient (decimal equivalent).
f) To determine the lbs of fertilizer needed = lbs nutrient divided by % nutrient (decimal equivalent).
g) If N+P₂O₅+K₂O is indicated, this means lbs of nutrients and not percentages.

1. What is the fertilizer analysis of pure NH₄NO₃? (at wts: N=14, H=1, O=16)

2. If 120 lbs of NH₄NO₃ were applied per acre, how many lbs of N are applied?

3. If 160 lbs of starter (6-10-8) were applied per acre, how many lbs of N, P₂O₅, and K₂O are applied?

4. If a soil test report calls for 80 lbs of K₂O per acre, how many lbs of muriate of potash (KCl) must be applied to meet this requirement?

5. Some fertilizers are "dual labeled" in that they have both elemental and oxide form on the label. Also, most scientific literature reports all nutrient analyses on the elemental basis. If a bag of fertilizer were labeled as containing 40% K₂O, what is the analysis when expressed as %K?

6. In a similar problem, assume the bag is labeled as 20% P. Calculate the percentage P₂O₅ in the bag.

7. If a 50-lb bag of urea (45-0-0) costs $8.00, what is the cost per lb of N?

8. If P₂O₅ is worth 38¢ per lb and a ton of pure K₂HPO₄ sells for $484, how much are you paying per lb of K₂O? Hint: must determine the pounds of P₂O₅ and K₂O (convert both to oxide basis) per 2000 pounds of K₂HPO₄.

9. Assume that you wish to make a bulk blend and add 300 lbs of 0-46-0 and 200 lbs of 0-0-60. What is the analysis of this blend (assume everything is on the oxide basis)?

10. A soil test report calls for 80 lbs P₂O₅ and 95 lbs K₂O per acre. You have 20 acres that need fertilized. If the source of P₂O₅ is 0-46-0 and the source of K₂O is 0-0-60, how many pounds of each fertilizer must you blend together to fill the truck going to the field? What will be the final analysis of the blended fertilizer?