Evaluating the distribution uniformity of ten overhead sprinkler models used in container nurseries

Nurseries and greenhouses face challenges of limited water supply and increased demand for irrigation efficiency to minimize runoff and mitigate water loss to the environment. Overhead irrigation systems are among the most widely used methods for container plants, particularly in small container sizes. However, there is a lack of research examining the distribution uniformity (DU) of the most used sprinklers in nursery settings. Our study investigated the DU of different overhead sprinkler types and models commonly used in outdoor nurseries in the United States to guide greater adoption of higher irrigation efficiency technology. Catch-can experiments compared ten different sprinkler models in small (4.6 m × 4.6 m) and large (9.1 m × 9.1 m) square experimental plots in Irvine, California. We measured water volume, wind speed, and operating pressure, and calculated the application rate for 189 test runs conducted between Mar 2020 and May 2023. Our results show that of the models tested, the greatest DU was achieved by the Hunter MP2000 at 276 kPa (DU = 0.78 ± 0.05) in the small spacing, and the Senninger Xcel Wobbler with a 3.97 mm nozzle at 172 kPa (DU = 0.76 ± 0.06) in the large spacing. Wind speed and operating conditions affected the DU and spatial uniformity of irrigation among the ten models, highlighting the importance of maintaining operating pressures at the manufacturer's recommendations to ensure optimal application rates and DU. Together these results offer a quantitative comparison of sprinkler performance at different operating pressure and in a wide range of wind speeds, allowing users to select sprinkler models that best fit their operation and maximize water conservation.