Question

Based on your fertilizer recommendations, you have to apply 92lbsP2​O5​ and 198IbsN per acre. Your fertilizer dealer carries only diammonium-phosphate (DAP; 18-46-0) fertilizer that contains P. How many pounds/acre DAP you have to apply to provide the required P2​O5​ nutrient to your crop?

Answer 1

To meet the requirement of 92 lbs of P2O5 per acre, one would need to apply 200 lbs of diammonium phosphate (DAP; 18-46-0) per acre because DAP contains 46% of P2O5.

Step-by-step explanation:

When calculating the amount of diammonium phosphate (DAP; 18-46-0) needed to supply the required P2O5 nutrient to a crop, we use the N-P-K rating system that indicates the percentage of nitrogen, phosphorus, and potassium within the fertilizer. DAP has an N-P-K rating of 18-46-0, which means that it contains 46% phosphorus, as P2O5. To provide the necessary 92 lbs of P2O5 per acre, we calculate the weight of DAP needed by dividing the desired amount of P2O5 by the percentage of P2O5 in DAP:

Amount of DAP needed (lbs/acre) = Desired P2O5 (lbs/acre) / P2O5 percentage in DAP

Amount of DAP needed (lbs/acre) = 92 lbs P2O5 / 0.46

After performing the calculation:

Amount of DAP needed = 200 lbs/acre

Therefore, to supply the required 92 lbs of P2O5 per acre, 200 lbs of DAP per acre should be applied.