2:41 PM
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Soil Fertility Lecture Guide_Chapter III.pdf
Learning Task
1. Solve the following sample problems on fertilizer calculations, show your solution and
encircle your final answer:
a.) If the N-P$_2$O$_5$-K$_2$O recommendation for 1 hectare is 90-80-50, calculate the amounts of the
following fertilizer materials needed using urea (45-0-0), complete fertilizer (14-14-14) and
solophos (0-20-0).
b.) Compute for the amount of fertilizers that is needed to satisfy the recommended rate of 90-
60-30 using ammonium sulfate (20-0-0), ammonium phosphate (16-20-0), and complete (12-12-
12) fertilizers in an area of 50m x 100m.
c.) Given: Area = 20 hectares
Recommended Rate = 100-90-60
Fertilizer Materials = 20-0-0 @ Php 165/bag
0-20-0 @ Php 265/bag
0-0-60 @ Php 300/bag
16-20-0 @ Php 280/bag
14-14-14 @ Php 395/bag
Conversion factor: 1 bag = 50 kilograms
Required:
1.) Find three (3) possible fertilizer combinations.
2.) Compute for the amount of fertilizers to be used in each combination.
3.) Based on the three (3) possible fertilizer combinations you have computed,
recommend or suggest for the cheapest fertilizer combination.