Page 183 - Calculating Agriculture Cover 20191124 STUDENT - A

CH 15] Calculating Agriculture 15-11

Example C: How many kg. of potash are furnished by 40 kg of Sulphate of Potash (60% K 20)?
_____________________________ kg K

Solution: (40kg) x (0.60) = 24 kg

Example D: A material containing a plant nutrient is called a carrier. Ammonium Sulphate is a
carrier often used as a source of nitrogen. Compute the number of kg. of Ammonium
Sulphate containing 21% nitrogen is needed to provide 80 kg of nitrogen.

______________ kg Ammonium Sulphate

Solution: (0.21) (AS) = 80 kg Nitrogen
Multiply 0.21 through by its recipro-
1 1 cal to maintain the equality of the
—— x (0.21) (AS) = 80 kg N x —— equation. This will isolate AS on one
0.21 0.21 side of the equation for the solution.
80 kg
AS = ——
0.21
AS = 380.95 kg

Example E: Compute the number of kilograms of Treble Superphosphate (45% P 20 5) that will
supply the phosphate in 800 kg of 6-10-4 fertilizer.

__________ kg Treble Superphosphate

(0.45) (TS) = (0.10) (800 kg)
Multiply 0.45 through by its reciprocal to
(0.10) (800 kg) maintain the equality of the equation. This
TS = —————— will isolate TS on one side of the equation
0.45 for the solution.
TS = 177.78 kg

Example F: How many kilograms of each are needed; Ammoniated Superphosphate (3-20-0) and
Ammonium Nitrate (36% N), to provide the nutrients in a 2 tonnes of 17-7-0
fertilizer?

____________ kg Ammoniated Superphosphate (AS)
15
____________ kg Ammonium Nitrate (AN)

To build an equation that resolves our question of how much of each is required, it is important to
set up simultaneous equations; one each for Nitrogen, Phosphorus, and then one for Potassium;
though Potassium in each is 0 (zero). In this problem, note that you are adding together separate
elements of Nitrogen (N) and Phosphorus (P), and Potassium (K) is not present (has a value of 0 )
and will be ending with a container of Nitrogen and Phosphorus mixed. As such, the parenthesis
( ) for separate N and P are combined ( = )in a single parenthesis ( ) for these elements.

Question: What is being mixed? = Question: What will you end with?
Separately Combined
( N ) + ( P ) = ( N + P ) Nutrient
( AS ) + ( AN ) = ( AS + AN ) Formulation

Next, you attribute the percentage strength of each factor with the equivalent decimal value. For the nitrogen
element, what is mixed is 3% Ammoniated Superphosphate (AS) and (+) 36% Ammonium Nitrate (AN) which is
mixed and ( = ) combined as 17% Fertilizer ( AS + AN ) that will weigh 2000 pounds. This equation becomes:

(AS + AN) Formulation with element strength (%)
N —> (0.03) (AS) + (0.36) (AN) = (0.17) ( 2000 kg ) and the weight. NOTE: The arithmetic
operation between the parenthesis is
multiplication.

INSTRUCTOR Copyrighted Material