Strategic watering
By Gordon Collie
Strategic watering pays dividends in Far North
Strategic irrigation in the wet tropics pays dividends in the form of consistently high crop production for the Gualtieri family who farm at Smithfield on the northern outskirts of Cairns.
Drainage works were an early priority for Mario Gualtieri, who has been growing cane in the Barron River floodplain since 1969. But a program of continuous improvement led to the introduction of a portable irrigation system in 2001.
Cane production is maintained through the combined efforts of Mario, who is semi-retired, and his son, Robert, who combines work on the farm with employment in the building industry.
Big floods
“It pretty much reflects the state of the industry,” said Robert, a diesel fitter by trade. There is no shortage of building work and I’m able to enjoy the rural lifestyle and manage the farm.”
They are proud of their record of continuous improvement and the farm is regularly among the local productivity award winners.
“When dad first bought the farm it was not even filling the 3000 tonne peak. Now we can grow better than 6000 tonnes.”
Production averages about 118 t/ha and in a good year can reach 125 t/ha.
The whole property except the house pad can go under water in big floods. Robert said the farm was in two distinct parts: low-lying heavy soil which consistently yielded well and sandy ridge country prone to drying out.
“We have found it is well worthwhile being able to water about 60 acres (25 ha) of the lighter country when we need to,” Robert said.
With two bores about 10 m deep providing an abundant water supply, they started out irrigating using a tractor-powered pump and hand-shift sprinklers. They have now upgraded to a travelling irrigator and Robert built a trailer-mounted pump unit with an 85 kW Cummins motor which puts out almost 70 000 L an hour.
“We generally irrigate the sandy ridges in the November-December period. Sometimes it might only need one watering, but it can make all the difference.
“If the crop dries out in this critical growth period it can be a major setback. With a timely irrigation the crop responds really well when the rains come.”
The two distinct soil types take careful managing to produce optimum results – everything from variety selection to farming regime.
“Q120 has been a good staple variety over the years. Q200 is a newer cane which has done pretty well and we are trying some Q220 this year to see how it goes. Q186 is more suited to the heavier ground. It’s one of the first to suffer when the ground dries out.
“We’ve been trash blanket farming most of the property for about 15 years now, but we need to make a careful judgement based on weather forecasts for the low-lying country.
Waterlogging can be a real challenge if we get big rains,” Robert said.
Their crop is being contract harvested and this year and Robert reluctantly engaged a contract billet planter.
“I’d much prefer to be still whole-stick planting as it uses so much less cane. But labour shortage has forced the issue,” He said.
Their fertiliser regime has been fine tuned, but Robert said any significant reduction was false economy.
“I tried cutting back a bag an acre and we lost so much production the following season it wasn’t funny.”
They get optimum results from a blend applied under the trash blanket comprising about 350 kg of urea, 300 kg of muriate of potash and 150 kg of DAP per hectare.
