Automated cycled sprinkler irrigation for spring frost protection of cranberries

Overhead (sprinkler) irrigation is commonly used for spring frost protection of cranberries in southeastern Massachusetts, United States. Historically, conventional forms of irrigation management have been used, generally consisting of running irrigation pumps continuously throughout the night and into the early morning until ambient air temperature reached 1-2 °C above the critical temperature of the plant. However, a general paucity of information exists on the horticultural and hydrological effects of on-off “cycling” of irrigation pumps based on pre-programmed temperature setpoints. To fill this gap, three years of monitoring were conducted to quantify the relative effects of cycled and conventional spring frost irrigation on cranberry bud damage, crop yield, and water use. Results showed that cycled irrigation reduced seasonal water use from 33 to 80% compared to conventional frost irrigation, with water savings under cycled frost irrigation ranging from 113 to 198 mm (mean ± SD: 176 ± 47 mm). Despite some variation in type and amount of observed bud damage, values of cranberry yield were similar between the two methods or higher for cycled irrigation. The conventional frost irrigation method always applied more irrigation water, possibly increasing soil saturation and anaerobic conditions that are known to lower crop yield in cranberry. Together, these results point to cycled irrigation as a water management strategy that can enhance cranberry production and reduce agricultural water use in southeastern Massachusetts.