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07 Nov 2018

Syphons through the bank irrigation system

In 2018 the Ag Resource Management team at Kaiuroo Aggregation began the major task of rebuilding the irrigated Leucaena system which was severely damaged by a major flooding event.

Three main areas were the focus for new design:

– Less labour.

– Less fuel.

– Apply water quicker. Only wet top 500 mm to maintain grass growth. Apply at a rate to overcome damming by grass and herbage.

After travelling through the Griffith/Moree areas it was decided to adopt a blend of ideas seen through the progressive areas of New South Wales to convert the traditional syphon design to a “through the bank” supply.

The tradition syphon system was expensive to maintain with the traffic of cattle and due to organics could not keep ditches sprayed free of weeds. The new design allowed the ditches to be built much wider and bigger to handle years of traffic and in time encourage them to grass over to help with future flooding.

Due to isolation logistics and cattle, the system needed to be simple and not mechanical. The number of syphons is based around 4ML/hour for diesel efficiency and 8 hrs to water a block.

The intensive finishing system is based around 3 blocks/section with a weekly rotation. Cattle moved then block is watered and in two weeks cattle back to first block for grazing.

Being able to get water on quickly have shortened watering time down from 48 to 8 hours and only wetting the top 500mm to maintain grass growth, which we believe is the most critical to constant high growth rates.

Flowrates to evenly water each paddock were calculated and varying syphon sizes were matched to the length of the rows. The hectares between Leucaena rows were individually calculated.

An extensive survey was done of all the paddocks utilizing elevation data from Kaiuroo’s John Deere guidance system and the new Komatsu Intelligent Machine Control base station. The Komatsu IMC system allows 3 dimensional plans to be loaded into an excavator to control bucket movement and dig surfaces to within 10 mm of design. This accuracy is needed to ensure that syphons are laid at exactly the same height in each supply group.

Four years of regular soil monitoring has shown amazing health improvements in the soil. The constant dropping of high protein leaves and the constant wetting and drying from vigorous roots of Leucaena and grasses leave no sign of compaction but the complete opposite. With the soil being in great health.

In summary the irrigation of Leucaena is now done by one person in one day on 25% of the diesel with much better grass growth. Stocking Leucaena at 2.5 AE/Hec with a growth rate of 1 kg/day if they do not have to work for their grass dietary requirements 365 days/year.

Area watered: 385 ha

Length of supply ditches: 6800 m

Number of syphons: 766

Average water supply to each field: 3.4 ml/hr

Average watering time per paddock: 8 hr

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