Water use efficiency in the cotton industry

  • Australian irrigated lint yields are now the highest of any major cotton producing country in the world, being about three times the world average. This means Australia's cotton growers produce more crop per drop than any other cotton producing country
  • The Australian cotton industry has achieved a 40% increase in water productivity over the last decade. (source: Australian Grown Cotton Sustainability Report 2014)
  • The CSIRO breeds appropriate cotton varieties for Australian and regional conditions. Each grower selects the best and most efficient variety for their region and farm
  • Cotton is an efficient plant, with the latest industry data showing approximately 70% of all water is used by the crop. This indicates that there is now less on-farm water losses and more of the water is used by the crop
  • Most cotton growers have what are termed “general, or low security” water licences, which means they only get to access their share of the water once the needs of towns, stock and domestic use and the environment are met
  • Cotton is only planted when sufficient water is made available from rivers and groundwater sources through government regulated water licensing schemes. When there’s no water, there’s no cotton
  • In their ‘natural’ state, the rivers located in the southern half of Australia experience more variable flows than virtually any other rivers in the world. Between 1885 and 1960, history shows the Darling River stopped flowing at Menindee on 48 occasions – well before irrigation existed on the river or its tributaries
  • Cotton is mostly grown in the 400-800mm summer rainfall zone, which means cotton crops can receive significant amounts of their water needs from rain during the growing season. In 2011-12 about 20% of the cotton crop was rain-grown, the rest irrigated
  • Australia’s cotton growers have improved water use efficiency by 3-4% per year since 2003. (source: Third Australian Cotton Industry Environmental Assessment, September 2012)
  • Australian cotton growers have almost doubled their irrigation water use index from 1.1 bales/megalitre in 2000-01 to 1.9 bales/megalitre in 2009-10
  • Cotton’s average irrigation requirement is 7.8 megalitres per hectare. This compares to rice (12.6ML/ha), fruit and nut trees (5.6 ML/ha) and cut flowers and turf (4.9 ML/ha)Pasture for grazing accounted for the greatest amount of irrigated land (538,000 hectares) in Australia in 2010–11, with the volume of irrigation water applied representing 27% of the national total. (source: ABS Water Use on Australian Farms 2010-11)
  • In 2013-14, the largest area of irrigated land in Australia was pasture and cereal crops used for grazing or fed off, which accounted for 714,503.2 hectares, or 30% of the total area irrigated (source: ABS Water Use on Australian Farms 2010-11)
  • The largest volume of irrigation water was applied to cotton, which used 2,851 gigalitres, or 26% of the national irrigation total for the year (11,060 gigalitres) (source: ABS Water Use on Australian Farms 2010-11). 566,000 hectares were planted to cotton in 2010-11.
  • Cotton is the lifeblood of many regional communities, employing 10,000 Australians in Queensland and NSW in a non-drought year
  • Each gigalitre of water used for cotton production results in 1.3 direct jobs and generates $500,000 in gross value agricultural production. (source: Stubbs Report, 2012)
  • Irrigation water for agriculture is used on the highest value crops.  Farmers choose to “spend” their water entitlements on the crops that deliver the best return per unit of water, in many areas that crop is cotton

Once planted, Australian cotton farmers are smart about the way they manage water resources. The Australian Grown Cotton Sustainability Report 2014 showed that cotton growers are using a range of techniques to constantly improve water use efficiency:

  • 70 percent of farmers use soil moisture probes, up from 40 percent in 2006 (highest of all agriculture industries in Australia)
  • 96 percent of irrigators have improved their furrow irrigation system or changed to an alternate irrigation system
  • 49 percent of irrigators had made changes to the flow or size of their siphons
  • 35 percent have redesigned fields. For example, growers use laser-levelling to ensure uniform, well drained fields using GPS guidance equipment and position storage dams closer to cotton fields to reduce evaporation losses
  • Other practices include irrigating to deficits, using drip and overhead sprinkler systems, better accounting of soil variations, changed bed shapes, using irrigation scheduling probes, furrow irrigation system optimisation evaluations, pump optimisation and reducing distribution losses

Additional water use efficiency driving practices include:

  • Before planting their crop, cotton growers use sophisticated weather forecasting software to predict how much crop can be sustained before planting. Zero and minimum till farming is also used to help retain soil moisture
  • Growers use information and technology (including soil moisture probes, satellites and drones) so they water only when and how much is needed
  • Irrigation channels that pump water to the fields are lined to reduce loss through seepage
  • Adhering to the Australian cotton industry’s environmental management program – myBMP. myBMP includes a water management module covering water quality, efficiency of storage and distribution for both dryland and irrigated farming practices to improve farming practices and carefully manage our natural resources
  • Farmers are changing to alternative irrigation systems such as centre pivots and lateral move systems and it is expected there will be an increasing number of these machines in the future. These systems can achieve labour savings and with some soil types, water savings (about 30 percent), but have significantly higher energy costs associated with water pumping and machine operation
  • Mobile electromagnetic meters are used for easy and rapid assessment of soils for their suitability for irrigation
  • Tail water recycling systems are implemented so that water is reused
  • Covering storages to minimise evaporation
  • Reducing evaporation by shortening row lengths
  • Avoiding unnecessary water storage on farm by only purchasing water as it is needed and not putting water directly into dry storages which soak up water
  • Growers are and lining storages and channels with clay or non-porous materials to avoid seepage. Thermal imaging and electromagnetic surveys can be used to identify “leaky” dams, pipes and channels so they can be repaired
  • Mulching and stubble retention helps to retain soil moisture, reducing the need for irrigations
  • Permanent wheel beds to reduce soil compaction and increase water infiltration
  • Implementing software packages such as Water Track (http://www.watertrack.com.au)

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© Cotton Australia 2016. This material is licensed under a Creative Commons Attribution-Non Commercial 4.0 International License (CC BY CC BY-NC 4)