Water Use Efficiency and Rice

Australian rice growers are some of the world’s most efficient producers. As an industry, Australia grows more top quality rice with less water than anywhere else in the world.

However, it is no easy task growing rice in Australia. You need water, and lots of it.

The Murrumbidgee and Murray Valleys (where over 99% of Australia’s rice is grown) has always used water sourced from reservoirs that rely on annual runoff - but there is now less water available for agricultural use since the implementation of the 2012 Murray Darling Basin Plan. Water has also become an annually tradable commodity. Huge variability of rice production exists each year, not only due to variations in water availability but commodity prices of a whole range of crops competing for the same water.

This pretty much means that the growth of the Australian rice industry depends on making the most of every drop of water! 

In this short article supported by findings from a May 2020 research report of NSW rice grower and Nuffield Scholar Mark Groat (who with support from AgriFutures Australia, travelled across the United States, South America, China and India drawing comparisons and insights for rice production back in Australia), we take a quick look at two considerations for Australian farmers to help grow more rice with less - rice genetics and irrigation efficiency.

We know most rice growers will have limited opportunities to change irrigation methods because they will need to apply large volumes of water to rice crops at high flow rates (flood irrigation). And even though current rice production practices in Australia may be some of the most efficient in the world, this doesn't mean that improvements can't be made. Water use efficiency and genetics selection is a good place to start

Rice Genetics

Traditional methods of selective breeding are being enhanced with new tools including gene technology which can manipulate the actions of a gene or to take a gene from one organism and move it into another.

In rice, 'functional' versions like rice enriched with iron, vitamins A and E, and lysine are being created. As too are rice plants engineered to have fewer stomata -- the tiny openings used for gas exchange -- so that they become more tolerant to drought and resilient to future climate change.

Drought-resistant plants share a mechanism known as crassulacean acid metabolism, or CAM, which allows them to survive despite low levels of water. CAM is essentially a form of photosynthesis in which the pores in a plant’s leaves only open to let in carbon dioxide at night.

During the day, when the sun is out, the pores remain closed in order to prevent water escaping through them. This means they are better able to tolerate dry conditions and as bioengineers build the blocks that make up CAM photosynthesis they will be able to bioengineer the metabolic processes of water-heavy crops such as rice, wheat, soybeans and poplar to accelerate their adaptation to water-limited environments.

Rice can be bioengineered to be enriched with iron, vitamins A and E.

Irrigation Efficiency

For many growers, the role of genetics is going a play a big part in water use efficiency (WUE). But there are countless other ways rice growers can reduce the number of spend hours monitoring and checking irrigation, checking moisture levels and turning on and off irrigation valves. This takes a lot of time, and time is money, The manual process can be very water and labour inefficient.

With smart irrigation solutions growers don't even have to leave their office to manage the precise irrigation of crops - they can do it using cloud-connected devices and dashboards on their mobile phone or computer. Getting this sort of set up is an investment but lower water allocations and higher water prices pose major challenges for the rice industry so increasing water use efficiency both in terms of production per megalitre and return per megalitre is an easy way to remain profitable.

“It’s about gaining a greater return for the water used, whether that’s in terms of yield, quality, consumer demand, or company reputation,” says Mr Groat in the research report.

Mr Groat's report also features a series of comparative case studies from international rice growing regions with similar geographic and climatic traits as Australia, such as the Mississippi Delta in the US, Uruguay, north-east China and north-west India. Irrigation management and reducing water use, just like in Australia, remains one of best ways to gain a greater return.

irrigation efficiency can provide a good return on investment for rice growers