As the forecast of the approaching El Niño grows in certainty and with the reporting of a drier and hotter summer than usual on its way, it is critical that production nurseries start to plan their water security. Recent commentary has highlighted the driest winter across most of Australia with Sydney experiencing the driest in 37 years and Brisbane is looking at combined dam storage below 70% with the winter total rainfall below 60% of average, and talk has already turned to water restrictions. Melbourne was 15% down along with Hobart at 30% below average while Adelaide and Perth were on average or slightly above. Darwin was 100% below the long-term average recording zero rain from the end of April to early October 2023, 161 rainless days. (Source: BOM)
The forecast for below average summer rain will put significant pressure on growers utilising on-site dams as temperatures are also set to rise therefore the potential to require increased irrigation cycles will draw down these supplies without adequate recharge occurring. Local government areas with limited reticulated water storages, or those under current supply pressure, will start to assess and plan for limiting water usage/restrictions noting that agriculture (plant production) is the first to have the tap turned off.
While a El Niño event, on average, lasts 12 months it is possible for them to extend across two years and with the impacts of climate change on our summer temperatures this could be a lethal combination. Greenlife Industry Australia (GIA) encourages all businesses to assess your water security and look at measures to mitigate wastage or improve efficiencies, now, as it will be too late if this event lasts into a second summer and we have the same low to average winter rainfall in 2024.
The following is an example of a grower looking at existing irrigation water sources and assessing the irrigation system and arriving at a retrofit and upgrade that secured their irrigation water and improved productivity. Assessments by GIA have shown that on average the nursery industry irrigates, by volume, 4.5 times more than is required giving industry ample room to move on system efficiencies.
“Every grower should invest in their business and upgrade their irrigation. I only wish I had undertaken the upgrade years ago. The financial and plant quality benefits of upgrading your irrigation are worth every dollar.” - Graeme Logan
Logans Nursery is an established tree and shrub nursery located on Brisbane’s Southside. The Capalaba West site containing 0.8ha of production area has been in operation for more than 20 years and the irrigation system has grown along with the business expansion over that time. A few years ago, Grame participated in a Department of Agriculture, Fisheries and Forestry funded project to assess and improve irrigation systems in production nurseries resulting in a retrofit and an upgrade to Best Management Practice (BMP) as part of a NGIQ industry project.
"Upgrading your irrigation system to best management practice makes good business sense." - Graeme Logan
The new irrigation system installed at Logans Capalaba West Nursery was designed under nursery industry BMP standards and provided a reduction in irrigation water use of 9.4 megalitres/year or 43% compared to the existing system. The irrigation system upgrade provided significant yearly dollar savings of $24,070 to the business. Importantly the irrigation water was sourced from both an on-site dam and via reticulated town water with both having different, yet connected, issues to mitigate including the dam maintaining enough water for use and the minimisation of reticulated water use due to increasing costs. The retrofit and upgrade worked to address these and other issues immediately upon completion.
Graeme Logan has encouraged growers to upgrade their irrigation systems since he completed his retrofit acknowledging the benefits surpass just saving water. The Logan Nursery irrigation upgrade delivered many benefits including:
Reduced irrigation water use from 21.7 to 12.3 ML/year
Savings of approx. $19,000 in town water costs alone
Improved irrigation application efficiency
Reduced labour costs in hand watering
A more uniform crop growth reducing labour cost in picking
An approx. 5% reduction in plant throw outs
Reduced plant disease outbreaks
Reduced pesticide applications
Better and safer working conditions
Improved irrigation water security
The irrigation system was upgraded to nursery industry best management practice and has delivered both financial and plant quality benefits to Logans Nursery.
The system upgrade included:
New Plastro sprinklers to outside and covered areas
A 5m x 5m sprinkler layout to BMP
Fixed 1.5 metre sprinkler risers to outside areas
A new irrigation main line to all growing areas
Improvement in system flow and pressure management
Adjustments to irrigation scheduling techniques
Catchcan tests of all production areas irrigated by the new system delivered results well within the parameters required by nursery industry BMP.
MAR - between 8 and 12 mm/hr (target <15mm/hr)
CU - in the low 90% (Target >85%)
SC - between 1.4 and 1.1 (Target <1.5)