Water
- Irrigation Overview
- Furrow Irrigation
- Overhead Irrigation
- Tailwater recycling
- Irrigation scheduling/water efficiencies
- Treated waste water
Irrigation Overview
The choice of the most suitable irrigation system for your farm will be influenced by soil permeability, farm topography, water availability and your financial situation.
Irrigators should always comply with licence conditions attached to their irrigation licence.
Furrow Irrigation
On free-draining, highly permeable soils, furrow irrigation is less suitable than overhead low pressure or trickle systems. Refer to Schedule 2 of the Code of Practice for current recommended practice.
Overhead Irrigation
When using overhead irrigation systems make sure the system is calibrated to soil type.
Green cane trash blanketing may be beneficial as the trash blanket slows water movement, allowing more time for infiltration and helps retain moisture in the root zone.
Take account of wind speed and direction to minimise water use and to reduce impact on non-target areas such as roads and houses.
Ensure strong cross winds do not blow water outside of the cropped area or cause uneven distribution of water within the field.
When using high pressure overhead systems, irrigate when conditions are calm or winds are light to moderate; still conditions are most common at night.
With centre pivot irrigation systems, take care to ensure that the application rate at the end-spans does not exceed the infiltration rate of the soil; with very large centre pivots, the application rate at the end-spans can be excessive.
Tailwater recycling
Consider the installation of tailwater storages where furrow irrigation is practised and/or where tailwater run-off occurs. This will:
- improve irrigation efficiencies;
- minimise run-off; and
- trap sediments, nutrients and chemicals suspended in run-off water.
Design of tailwater storages should ensure that off-farm run-off from irrigation does not exceed 10% of irrigation inflow rates.
Construct recycling storages in accordance with Department of Natural Resources Rural Advisory Service specifications: Section B - Earth Dams and/or Section BM - Earth Dams with Membranes.
Irrigation scheduling/water efficiencies
Schedule irrigation with evaporation mini-pans and/or soil probes calibrated to stalk growth measurements and soil type.
BSES target water use efficiencies are listed in Schedule 2 of the Code of Practice (page 26).
Treated waste water
Effluent water should be applied only if -
- the effluent is of appropriate quality;
- the soils have appropriate permeability; and
- ground water is at sufficient depth to prevent its contamination.
Guidelines for the reuse of sewage sludge and effluent on cane are currently being developed by CRC Sugar and DNR.
