Royal Botanic Gardens Melbourne: Mixed plantings irrigation management
The challenge of mixed plantings management, whether in a garden, natural vegetation or permaculture
environment, is that detailed knowledge of the whole soil water profile dynamics is required to fully address the water needs of the entire plant community.
The Royal Botanic Gardens Melbourne had historically been using irrigation scheduling methods developed for
monocultures, which were recognized as not being entirely appropriate. The results of using these techniques in a
complex, multi-tiered mixed planting landscape were beginning to take their toll on some of the more vulnerable plants in the gardens, and steps were being taken to optimize the growth for the available water. However, understanding the water cycle in this complex mix of plantings was difficult.
In 2007 the Royal Botanic Gardens Melbourne, The University of Melbourne and Sentek Sensor Technologies Pty. Ltd. embarked on a research project to develop quantifiable rates of landscape water use in complex plantings. Sentek EnviroSCAN Plus and Diviner 2000 soil moisture probes were installed at various locations throughout the gardens to supplement existing weather station data. Results of this data integration were then used to aid managers in their irrigation decisions. From this study, the researchers developed a new numerical index, the Evapotranspiration Stress Index (ETSI).
ETSI = Evapotranspiration
Daily water use
The ETSI can be used by irrigation managers to ensure the whole planting stays within pre-defined plant stress limits (thresholds). Central to the development of this new theory was Sentek's IrriMAX™ software. This specialist graphing platform allows data from all the collection points to be displayed simultaneously and visually manipulated to reveal the intricate details of the plant's response to water stress