Rice may flourish using less water

There are encouraging signs from a new study at the Yanco Agricultural Institute that delaying flooding could be a successful strategy for saving water without loss of rice production.

The investigation was prompted by an industry hit hard by the water shortage and anxious to find ways of producing with less.

Contributing to the research effort is the National Program for Sustainable Irrigation, with input from CSIRO’s irrigated farming systems expert Don Gaydon and research and extension staff of the NSW Department of Primary Industries.

Traditionally rice in Australia has been either drill-sown followed at the three leaf stage by an application of water which is maintained, or pre-germinated seed has been aerial sown over the watered bays. The latter method accounted for about 80% of the area sown when water was more plentiful.

Several years ago NSW Department of Primary Industries trials on water saving used flushes of irrigation at different intervals, starting from an early growth stage. These trials generated useful information, as did the experiences of several ricegrowers who tried modest delays in applying water or flushed crops at the first signs of stress. A more comprehensive set of treatments which started at Yanco in 2008-09, however, will build on scientific knowledge and extend results and management guidance to ricegrowers.

Research agronomist Brian Dunn of NSW Department of Primary Industries is working closely on the project, being sub-contracted to CSIRO to undertake experiments on delayed application of permanent water. In the first season of the study, in which all relevant parameters are being measured using replicated plots and various delay periods and irrigation frequencies, some encouraging results emerged. At the most extreme level there was a 16% water saving and the yield of 10.1 tonnes per hectare compared with 10.9 tonnes per hectare from conventional practice.

The size of the experiments at Yanco, coupled with the participation of ricegrowers in demonstrations of the technique of delaying water, means results can be extrapolated to apply to commercial properties.

In the current season aerial-sown plots will be added to drilled plots as controls for making comparisons of delayed techniques with conventional methods.

“Although results so far appear to be bright for both economic and environmental reasons, particularly since last season was extremely hot, recommendations cannot be made until the conclusion of the project,” Brian Dunn said. “Two or more extra seasons of data will be very useful.”

One matter requiring further investigation is nutrient management because most studies of nitrogen and phosphorus demand have been based on conventional methods.

An interesting observation has been the quick recovery of stressed rice plants. With a 22 week to 23 week growing period, it can be expected that a nine week old plant yet to get its permanent water will be very stressed, with reduced biomass and height compared to plants better served with water and nutrients. Once stress is reduced, however, and there is the temperature-moderating effect of ample irrigation, plants pick up and production losses do not appear to be as high as growers once thought would be the case.

Caption: At the experimental site at Yanco, Brian Dunn takes measurements to compare the effects of delayed water on rice.

Citation

Land & Water Australia. 2010. Rice may flourish using less water . [Online] (Updated March 30th, 2010)
Available at: http://lwa.gov.au/node/3727 [Accessed Saturday 31st of July 2010 01:50:14 AM ].