How does a La Nina summer impact agriculture?

By: Anthony Wingard

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History tells us that this summer’s La Niña conditions are more likely to be positive than negative for agriculture – but planning is crucial. By Anthony Wingard

This summer will see higher than average rainfalls

It’s little secret that farming in Australia is a tough gig at the best of times, given its largely dry and harsh environment.

That’s why the Bureau of Meteorology’s (BoM) declaration on November 23 that a La Niña weather system had developed in the tropical Pacific Ocean caused quite a stir amongst the agricultural industry.

The system is expected to persist in the southern hemisphere until late in the summer and may even stick around until early Autumn, and with it, an above average rainfall is now expected across the eastern seaboard states.

For Professor Graeme Hammer – a professor in crop science at the University of Queensland’s Queensland Alliance for Agriculture and Food Innovation (QAAFI) – says La Niña conditions will likely be a positive for farmers who use water well – saying they can "actually make grain from rain".

"La Niña means we’ve got the best wheat crop out there in a long time so there’s a big positive. In general, it’s a real positive for the country," he says.

This summer will mark a second consecutive year that La Niña event has occurred, following the 2020–21 event that was almost entirely localised within New South Wales – and consistent rain throughout these periods have helped to boost the agriculture sector.

Figures from the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) has projected this year’s winter harvest will be a new national record of 58.4 million tonnes.

The benefits of the favourable growing conditions are also expected to extend onto summer cropping as well, with total planted area expected to increase by as much as 36 per cent to maximise soil moisture levels.

"These are the years where farmers can actually do very well. Farming in Australia is about how you use your water, and these are the sorts of years when you’ve actually got some, so then you’re able to adapt your management to make the most efficient use of it," says Hammer.

"There will be periods like now where it will dry out enough to get a crop in and follow up rain is more likely than normal so in most instances, this is the sort of year where you would intensify your management because you’re likely to get high yields.

"Certainly, having good rotations in place with good surface management is critical so, when you get that heavy rain, you get that water going into the soil."

According to Hammer, it’s up to farmers to maximise their farming operations to take advantage of La Niña, given the alternative – El Niño – means an increased likelihood of drought.

"This is sort of like the three years in 10 where you can make 70–80 per cent of your profit. You make grain when it rains, and you pull your head in when it doesn’t," he says

"El Niño is where you have to survive so you can hopefully get these years when you have rain and plenty of water and you can do something with it."

Lessons of history

The last time Australia had two consecutive La Niña years was in 2010–11 and 2011–12 – years that wreaked havoc on the agriculture industry.

Unrelenting rain led to floods throughout Queensland and Victoria as well as parts of New South Wales, destroying crops at an estimated value of $1.6 billion.

Horticulture enterprises was hit particularly hard, with the widespread loss, damage and disruption of fruit and vegetable harvests. Other agricultural sectors, such as livestock, sugar cane and the grain sector, were also impacted.

Hammer says events such as these are typically associated with extreme rainfall at a particular point in time – a trend that tends to be much more common during La Niña periods.

Whether this summer’s La Niña event will result in widespread flooding throughout the eastern states remains unclear – little modelling exits to predict the severity of individual events given the complex nature of La Niña periods.

"The downside of the La Niña is the increased chance of flood but farmers won’t be able to do too much about that anyway… there is not a hell of a lot one can prepare for," says Hammer.

"It’s going upset horticulture farmers because they can’t keep up the continuity of supply and it’s going to interfere with the harvesting of broadacre crops."

Regardless, excessive rain is expected this time around, and while there is little evidence to suggest consecutive La Niña events have a cumulative effect, it’s worth noting the impact of the most contemporary severe La Niña year.

As outlined in the 2012 ABARES Australian crop outlook, published in February following two successive La Niña summers, yield prospects for summer crops remained favourable and both upper- and lower-layer soil moistures reached near record levels.

"Since flooding generally affects low-lying areas that comprise a small proportion of crop area, the effects of flooding on summer crop production tend to be localised," the report reads.

Winter crops, which were harvested across the summer months amidst La Niña, were only slightly impacted. Underpinned by bumper Western Australia crop production, the 2011–12 winter harvest reached 43.4 million tonnes with growth seen in wheat, barley, and canola.

In southern Queensland and Northern NSW, most of the harvest was completed before the floods occurred.

This summer, NSW Farmers was quick to call upon state and federal leaders to declare a natural disaster following torrential rains and localised flood damage across the state.

A declaration would allow government grants and concessional loans to be handed out, in addition to other relief support, to help farmers cope with the potential losses.

"Part of farming is dealing with nature, but it is cruel for our growers to watch these amazing crops – this potential income after so many years of drought – drowned before they could be harvested," NSW Farmers grains committee chair Justin Everitt said in a statement.

"We urgently need a range of measures to help people start to clean up and get on with their lives."

For Hammer, the best thing farmers can do is be proactive in their farm management, both when there is significant rainfall and during drier periods.

"I think just being aware that there is a La Niña in most instances is like ‘be prepared to take advantage of having more water than normal’, so it’s about intensifying your management," he says.

Hammer also issued a warning for farmers of potential hard times ahead.

"The only this is that the next El Niño is not far away, and people tend to think that it’s a very in the moment thing, but climate variability needs to get over that way of thinking.

"Farmers need to think about decades and not that it’s wet this year and dry next year," he says.

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