5 November 2014
A horticultural operation has obtained a 17 year extension to a ten year licence that will see 54,000 megalitres of water extracted from the Ti Tree basin aquifer in the Northern Territory.
TTG Nominees’ Territory Horticultural Farm can now act on expansion plans and continue to use 2,000 megalitres of water annually until 2038.
But Dr Peter Cook, principal research scientist at the CSIRO, says the sustainable water yield estimate for the Ti Tree Basin aquifer is ‘highly uncertain’.
Mr Cook says ongoing monitoring of the aquifer’s water and salinity levels along with knowing how spread out the extraction locations are will be important.
Agribusiness manager for Southern Cross Farms, Peter Morrish, is in charge of Territory Horticultural Farm.
Mr Morrish says the extended water licence is a bid to inspire financier confidence and they can now get on with planting lemon and mandarin trees.
“For investment in citrus [financiers] need 15 to 20 years to get a return,” he said.
“The major factor in growing [citrus] crops is water and a ten-year licence doesn’t provide enough security.”
The Northern Territory Government says extended water extraction licences are needed to attract investors to expansion plans.
NT Minister for Land Resource Management, Willem Westra van Holthe, says Ti Tree is an ideal area for horticultural expansion, especially given its isolation from the Cucumber Green Mottle Mosaic Virus that is devastating Top End horticulturalists.
“Ti Tree has been in the past and will be in the future a very important region in the Territory for horticultural development,” he said.
“The region was the beginning of the table grape industry and now they are also growing melons and pumpkins.”
Mr Morrish says the Territory Horticultural Farm includes 200 hectares of land that can be irrigated, but only 70 hectares is currently used for melon and pumpkin plantations.
“We will be planting trials over the next couple of years to look at long-term options,” he said.
“At this stage, there is a small planting of citrus that is in the ground.
“We will be looking at other permanent crops going forward.
“The property used to be table grapes and that probably won’t be an option because of competition from eastern states.”
Mr Morrish emphasises that the farm’s strategy is to look at permanent crops for niche markets.
Whilst permanent crops might be the focus of current tests, Mr Morrish points out that the long-term approach will include a mixture of permanent and annual crops.
“Due to the level of water extraction, it all depends on the availability of water… and land,” he said.
“The present trial is lemons.
“Oranges, probably not, because of the maturity/colouring timing and competition with eastern states.
“We will be looking at ‘easy-peel’ mandarins,” he said.
The ongoing water extraction licence, combined with other licences and unlicensed use, means almost half of the Ti Tree Basin aquifer’s estimated annual sustainable yield will continue to be used.
Mr Morrish says the business remains committed to monitoring water use to ensure sustainability.
“I don’t know if exploitation is the right word,” he said.
“We are under strict control requirements in terms of measuring our water use and measuring the water tables so that the extraction is monitored.
“[The aquifer] is also regularly monitored by government agencies to make sure it is not being overused.
“Therefore [the aquifer and water] is used in a sustainable manner,” he said.
The CSIRO’s Peter Cook says the sustainable water yield estimate for the Ti Tree Basin aquifer is ‘highly uncertain, as it is with a lot of our groundwater basins’.
“There is research going on at the moment to get a more accurate number,” he said.
“The real focus should be on carefully monitoring the groundwater use and ensuring the groundwater levels don’t decrease excessively and interfere with other users.”
On the scale of the horticultural farm after development, Mr Morrish says they would be looking to have up to 50 per cent of the 200 hectares under permanent plantings.
“We have four permanent staff there at the moment and that could go to seven or eight.
“Itinerant worker levels will continue to fluctuate throughout the year and we can have up to 50 at harvest times, even with just the 70 hectares of melons and pumpkins,” he said.
Dr Cook says keeping tabs on the water is not only about extraction levels.
“One of the questions will be exactly where the water is taken out of.
“And it will make a difference whether the water is all extracted from a very small area or spread out over a greater region.
“Monitoring salinity is important as a lot of the groundwater in Ti Tree, as in other arid zones, is saline.
“There are only pockets [of water] sometimes that are suitable for use and we need to protect them.”
Courtesy of ABC Rural