Page 12 - Azerbaijan State University of Economics

XiaolinQu, M.S., Lal K. Almas: The water requirement and profitability analysis of corn using irrigation
management approaches including evapotranspiration and weather data

In order to show the impact of a change in the price of fuel to the cost, a range

of fuel price from $2/mcf to $7/mcf is applied in the calculation of cost. In the

calculation of FULC, natural gas is used since it is the predominate source of

energy for pumping irrigation water in the Texas Panhandle area. The fuel cost

(FULC) is equal to the product of the amount of fuel used (NG) multiplied by the

price of the fuel (PNG)(Equation 2) (Colette et al. 2004).

FULC = NG*P NG (2)

Where NG is the amount of natural gas used in million cubic feet (mcf), P NG is

the price of natural gas ($). The amount of natural gas needed (NG) to pump one

acre-inch of water differs among irrigation systems (Equation 3) (Almas, 2000).

2
NG= 0.0038*L+ 0.0088*PSI – 0.000007623* PSI*L – 0.0000033*L (3)
Where L is the system lift in feet and PSI is the system pressure per square inch

The NG, LMR, LC and AIC are known constants for a given irrigation system

(Almas et al, 2000). For example, the total cost function for a typical Low

Elevation Spray Application (LESA) system with a 350 foot system lift can be

expressed as Equation 4. And Equation 4 is the cost function being used in this

study to analyze the optimum problem across the three water approaches.

TC= FC+ (1.018*P NG +4.04 + 0.56+1.06)*W= FC+ (1.018*P NG + 5.66)*W (4)

Where W represents the water approaches including total available water,

irrigation application and PPET. Marginal Factor Cost (MFC) represents the

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