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ON-FARM DEMONSTRATION STUDY:

Portable Pump-Back System

Tailwater reuse systems provide a means for conserving water by reusing tailwater from row or flat irrigation applications. To test the effectiveness of these systems, the Team worked closely with Ralph Strahm to study the impact of a portable pump-back system set up on a 72-acre melon field. The system developed by Ralph relied on a standard gated pipe setup to split the field into eighth-mile long furrows. It also used a reverse grade ditch to return the drain water nearly back to the lower end of the field’s head ditch. Finally, a Crisafulli pump with only a short run of 10-inch aluminum pipe was sufficient to pump the drain water into the head ditch, where it backed up far enough to irrigate from its lower half. This made it possible to apply the pumped-back water to about a quarter of the field.

The preliminary results are as follows:

• Ralph and his irrigator were able to supply most of the water for this quarter of the field with the pump-back water by carefully managing water orders and field operations. Five irrigations were applied and the total measured volume of water delivered was 111 AF or about 18.5 inches depth on the 72-acre field.
• The total measured (and estimated) tailwater spill was about 11.2 AF or about 10 % of the delivered water. The amount of water conserved was between 20 to 25 AF or about 0.25 to 0.33 AF/acre.
• The cost of achieving this was five days of additional irrigation labor, about 240 gallons of diesel fuel to operate the pump, and a fair return on the $14,000 (or about $200/acre) cost of his tractor PTO-powered Crisafulli pumping unit and aluminum pipe.