Top 5: Saving Irrigation Water and Money

This article appears in the February 2018 issue of Potato Grower.

One of the biggest expenses of any potato-growing operation is properly irrigating those precious plants. As growers gear up for the upcoming season, here are five tips to help them save water and money—and grow a healthier, higher-yielding crop in 2018.

1. On set systems (hand lines, wheel lines and solid set), replace worn nozzles and fix system leaks to reduce unintentional over-pumping. This will reduce required hours of irrigation to meet crop needs while saving water and reducing energy costs. Leaks and worn nozzles also reduce system pressure on set systems, resulting in lower application uniformity. Average water and energy use due to leaks and worn nozzles was 25 percent higher than needed based on recent test results from 30 set system laterals in southern Idaho.                                 
2. On pivots or linears, replace the sprinkler package, or at least the pressure regulators, about every five to seven years. Moving pressure regulator parts stop moving freely due to accumulated mineral deposits, resulting in lower system application uniformity. Sixty-five percent of the 30 pivots tested had measured uniformities low enough to require sprinkler package replacement.                                                                                                      
3. Consider dropping sprinkler heads to just above the potato canopy to reduce water losses to evaporation and wind drift. This can reduce irrigation application by 15 percent or more, but may require reducing sprinkler spacing to a maximum of 10 feet—or even 5 feet—depending on water droplet trajectory.                                      
4. Use some type of irrigation scheduling to avoid over-irrigation. This is most likely to occur in early or late season, or during periods of very hot weather in mid-season when crop water use of the potato crop drops in response to the very hot conditions. Over-irrigation uses more water and energy inputs and creates conditions more favorable for development of plant disease.                                                                                                       
5. On pivots with new sprinkler packages, or pivots new to your operation, take the time to walk the pivot, checking that the nozzle sizes correspond to sprinkler chart numbers. Incorrect nozzle size for the location occurs more frequently than you might expect. The time required to check will be well worth it if mistakes are discovered before the season starts, rather than noticing a bull’s-eye pattern of over- and under-watering in a critical period in mid-summer.