How many pounds of MAP fertilizer are needed for an 80-acre field if the recommendation is 40 pounds P2O5 per acre?

To determine the correct amount of monoammonium phosphate (MAP) fertilizer needed for an 80-acre field with a recommendation of 40 pounds of P2O5 per acre, it’s important to first calculate the total pounds of P2O5 required for the entire field.

Start by multiplying the recommendation of P2O5 (40 pounds) by the total number of acres (80 acres). This results in:

40 pounds P2O5/acre * 80 acres = 3,200 pounds of P2O5 needed for the entire field.

Next, since MAP contains both phosphorus (P) and nitrogen (N), we need to convert the pounds of P2O5 into the equivalent pounds of MAP. The molecular weight of P2O5 is 142, while that of MAP is 149. This means that for every pound of P2O5, you need approximately 1.06 pounds of MAP to deliver that phosphorus.

To find the total MAP required, multiply the total pounds of P2O5 (3,200) by the conversion factor:

3,200 pounds P2O5 * 1.06 ≈ 3,392 pounds MAP.

However, MAP is often rounded