Application Method Affects Water Application Efficiency of Spray Stake-irrigated Containers

Abstract

Studies were conducted to evaluate the effect of water application medium moisture deficit, water application rate, and intermittent application on water application efficiency {[(amount applied - amount leached)/amount applied] x 100} of spray stake-irrigated, container-grown plants. Pine bark-filled containers were irrigated to replace moisture deficits of 600, 1200, or 1800 ml; deficits were returned in single, continuous applications of 148, 220, or 270 ml·min -l . Efficiency was unaffected by application rate but decreased with increased medium moisture deficit. In the second experiment, container medium at a 600-ml deficit was irrigated with 400 or 600 ml (6570 and 100% water replacement, respectively); deficits were returned in a single, continuous application or in intermittent 100-ml applications with 30-min intervals between irrigations. Application efficiency was greater with intermittent irrigation (95% and 84% for 400- and 600-ml replacement, respectively) than with continuous irrigation (84% and 67% for 400- and 600-ml replacement, respectively). In the third experiment, pine bark was irrigated with 600 ml water (100% replacement) in 50-, 100-, or 150-ml aliquots with 20, 40, or 60 min between applications in a factorial design. Efficiency increased with decreasing application volume and increasing time between applications. Highest efficiency (86%) was achieved with an irrigation regimen of 50-ml applications with at least 40 min between applications, compared to 62% for the control treatment (a single, continuous application of 600 ml). Our results suggest that growers using spray stakes would waste less water by applying water intermittently rather than continuously.