# Conversion for Diesel Fuel for Center Pivots

### September 19, 2008

The 2009 crop production budgets with center pivot irrigation were developed with a pumping lift of 125 feet and 35 psi pressure to determine the amount of diesel fuel. A table was developed by Derrel Martin to determine the amount of diesel fuel for various pumping lifts and various pressures to pump an acre inch of water.

For example, the amount of diesel required to pump an acre inch of water with 125 feet of lift at 35 psi is 1.88 gallons with a pump performance rating of 100%. If the producer has a lift of 300 feet and a pressure of 50 psi the diesel fuel required at a performance rating of 100% is 3.79 gallon per acre inch. If the rating on the producer's pump is 80% the diesel fuel required will be 4.74 gallons per acre inch of water.

The producer then could calculate the additional cost since the diesel fuel required is now 4.74 gallons per acre inch vs 1.88 gallons per acre inch or 2.86 gallons more per acre inch. If a crop budget requires 9 inches the additional diesel fuel would be 9 inches x 2.86 gallons = 25.74 gallons of diesel at \$4.00/gallon. The producer's additional costs could be \$102.96/acre.

Robert Klein
Extension Cropping Systems Specialist

 Table 1. Table for adjusting the amount of diesel fuel required for center pivots for lifts and pressures other than the 125 feet of lift and 35 psi used in the budgets. Gallons of diesel fuel required to pump an acre inch at pump performance ratings of 100%*. (From Estimating the Savings From Improving Pumping Plant Performance by Darrel Martin). Lift Pressure at Pump, psi Feet 10 20 30 35 40 50 60 80 0 0.21 0.42 0.63 0.74 0.84 1.05 1.26 1.69 25 0.44 0.65 0.86 0.97 1.07 1.28 1.49 1.91 50 0.67 0.88 1.09 1.20 1.30 1.51 1.72 2.14 75 0.89 1.11 1.32 1.43 1.53 1.74 1.95 2.37 100 1.12 1.33 1.54 1.65 1.75 1.97 2.18 2.60 125 1.35 1.56 1.77 1.88 1.98 2.19 2.40 2.83 150 1.58 1.79 2.00 2.11 2.21 2.42 2.63 3.05 200 2.03 2.25 2.46 2.57 2.67 2.88 3.09 3.51 250 2.49 2.70 2.91 3.02 3.12 3.33 3.54 3.97 300 2.95 3.16 3.37 3.48 3.58 3.79 4.00 4.42 350 3.40 3.61 3.82 3.93 4.03 4.25 4.46 4.88 400 3.86 4.07 4.28 4.39 4.49 4.70 4.91 5.33 *Multiplier when pumping plant performance rating is less than 100%. Rating %         100      90        80        70        60        50 Multiplier          1.00     1.11     1.25     1.43     1.67     2.00