[ASC-media] Media release: more rice, less water
crca-media at starclass.com.au
Mon Mar 22 23:09:51 EST 2004
CRCA Media Release 04/13
March 23, 2004
MORE RICE FOR LESS WATER
A new Australian method for selecting low water-use soils for rice production and reduced risk of salinity is being adopted by rice farmers.
Australia is already one of the world's most water-efficient rice producers in the world, says Mr Geoff Beecher of the Cooperative Research Centre (CRC) for Sustainable Rice Production. The new technique takes us one better.
The new approach uses electromagnetic induction to create a picture of the soil to a depth of five metres or more, allowing targeted soil sampling combined with the evaluation of soil chemical properties such as sodicity. Soil sodicity is linked to decreased soil permeability especially in clay soils.
Used together, these techniques help minimise the amount of irrigation water which escapes into the groundwater system, he says.
The method uses a Geonics EM-31 instrument mounted on a 4WD motor cycle to carry out rapid field surveys to help pick the land likely to use the least water.
"Rice is a major export crop, worth over $350 million in a good year," says Mr Beecher, "but today's rice farmer must meet stringent controls to keep the industry sustainable and to satisfy environmental standards.
"The main threat to all irrigated agriculture in southern Australia is salinisation due to rising water tables," he says.
"Since the 1960s soil assessment of rice growing areas has been undertaken to identify where the soil doesn't 'leak' - that is, where irrigation water cannot escape into groundwater and raise the water table. Until the introduction of the new electromagnetic techniques, soil sampling to establish where rice could be grown was relatively simple, says Mr Beecher.
"The rule of thumb related the depth of clay in the soil to the amount of 'leakage' through the soil into the groundwater," says Mr Beecher. "Soil evaluation sites were selected on a grid basis, with one site per four hectares. There was also some attempt to use aerial photography to locate sites where the subsoil clay could be insufficient.
"But a multitude of chemical and physical factors can affect groundwater recharge, as well as local management practices," says Mr Beecher. "The grid system gave a fair indication of soil characteristics on a regional basis, but was far from accurate."
Mr Beecher says that electromagnetic induction surveys enables the farmer to make a rapid and comprehensive survey of land to select those areas most suitable for rice growing.
"The instrument senses variation in bulk electrical conductivity in the soil. The instrument responds to variations in salinity, clay content, moisture, and the bulk density of the soil. This electromagnetic surveying is then backed up by targeted soil sampling combined with evaluation of soil chemical properties."
Mr Beecher foresees many possible uses for the soil electrical conductivity data collected during the electromagnetic surveying technique developed by the CRC.
"Electromagnetic induction surveying maps may have an important role to play in precision farming allowing zoned management of fields for more controlled use of fertilisers/soil amendment inputs (lime/gypsum), saving the farmer money, giving higher yields for every dollar spent and protecting the environment," he says.
The technique may also be useful for locating suitable sites for dams and off-river water storage facilities.
Australia's rice crop grows on an average area of around 150,000 hectares. The industry's goal is a production standard of more than ten tonnes of grain per hectare.
Mr Beecher says that the industry also has a target of one tonne of rice per megalitre of water; the current figure is about 700 kilos/Ml.
The new soil testing approach, which is now available to farmers through the CRC, will be a major step in achieving both goals - while at the same time helping to prevent salinity and provide water for the environment.
2004 is the International Year of Rice.
This research serves National Research Priorities One (an Environmentally Sustainable Australia) and Three (Frontier Technologies for Building and Transforming Australian Industries).
Geoff Beecher, CRC for Sustainable Rice Production 02 6951 2725
0428 533 478
Julian Cribb, CRCA Media 0418 639 245
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