Studies were conducted to evaluate the effect of pre-irrigation media
moisture deficit, irrigation application rate, and intermittent irrigation on irrigation
efficiency [(amount applied - amount leached) amount applied' 100] of spray
stake-irrigated, container-grown plants. In the first experiment, pine bark-filled
containers were irrigated to replace moisture deficits of 600, 1200, or 1800 ml.
Deficits were returned in single, continuous applications at application rates of
148, 220, and 270 ml/min. Application rate did not affect irrigation efficiency.
Efficiency decreased with increased medium moisture deficit. In the second
experiment, containers, at 600 ml media moisture deficits, were irrigated with 400
or 600 ml (65% and 100% water replacement, respectively). Irrigation volumes
were returned in a single, continuous application or in 100ml applications with 30
min intervals between irrigations (intermittent). Irrigation 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. When applied intermittently, most water loss from containers occurred after 400 ml were applied. In the third experiment, containers
were irrigated with 600 ml (100% water replacement) in 50, 100, or 150 ml
applications with 20, 40, or 60 min intelVals between applications. A control was
included in which 600 ml was applied in a single, continuous application.
Irrigation efficiency increased with decreasing application volume and increasing
length of interval between applications. The greatest efficiency (86%) was
produced with an irrigation regimen of 50 ml applications with at least 40 min
between applications. The control treatment (continuous) produced an irrigation
efficiency of 62%. When applied intermittently, most water loss from containers
occurred after a total of 300 ml were applied.