Wheat and weather

Farms & Farm Machinery - - Contents -

Re­cent CSIRO re­search has found that Aus­tralia’s yield po­ten­tial, par­tic­u­larly in the wheat-grow­ing zone, has ex­pe­ri­enced a de­cline of 27 per cent over the last 25 years.

The team found that wheat was par­tic­u­larly af­fected by an av­er­age rain­fall de­cline of 2.8mm – or 28 per cent – per crop­ping sea­son, and a max­i­mum daily tem­per­a­ture in­crease of around 1C from 1990 to 2015.

This poses a risk to Aus­tralia’s more than $5 bil­lion per an­num wheat in­dus­try, which con­trib­utes around 12 per cent of the to­tal wheat traded world­wide.

CSIRO se­nior prin­ci­pal re­search sci­en­tist Dr Zvi Hochman says the ob­ser­va­tions are con­sis­tent with the higher end of fu­ture cli­mate change pro­jec­tions for the wheat zone over the com­ing 26 years.

“Our re­sults are a se­ri­ous con­cern to the fu­ture liveli­hood of wheat farm­ers in mar­ginal grow­ing ar­eas and to the Aus­tralian econ­omy, as well as fu­ture global food se­cu­rity,” Hochman says.

“Wheat farm­ers are mak­ing the most of de­vel­op­ments in farm­ing tech­nol­ogy and adapt­ing them to their needs.

“How­ever, their best ef­forts are merely en­abling them to keep pace with the im­pacts of a chang­ing cli­mate.”

He says the dif­fer­ence be­tween ac­tual yield and po­ten­tial yield is clos­ing as farm­ers are man­ag­ing to main­tain yields at 1990 lev­els of around 1.74 tonnes per hectare.

Ac­cord­ing to Hochman, “1990 was a wa­ter­shed year for Aus­tralia’s wheat in­dus­try, with a con­tin­ued de­cline trend in yield po­ten­tial since that year”.

The study an­a­lysed 50 weather sta­tions with the most com­plete records across Aus­tralia’s wheat grow­ing re­gions, span­ning five states from the east to the west coast.

“We found that the loss of yield po­ten­tial is not evenly dis­trib­uted across Aus­tralia’s wheat zone.

“While some ar­eas have not suf­fered any de­cline, oth­ers have re­duced yield po­ten­tial by up to 100kg per hectare per year.

“The clos­ing of the gap is driven by both tech­no­log­i­cal ad­vances in­clud­ing bet­ter wheat va­ri­eties and bet­ter prac­tices.

“So to find out what has hap­pened to yield po­ten­tial we were keen to work with high-qual­ity weather sta­tions.

“They had to be lo­cated in an area which was a sig­nif­i­cant wheat grow­ing area,” Hochman says. “They also had to be at least 20km away from each other so that each one was telling us some­thing dif­fer­ent.

“We then found that they were also rep­re­sen­ta­tive of 10 of the agro-eco­log­i­cal zones, and that meant that they rep­re­sented more than 95 per cent of the area and that they also did a good job of rep­re­sent­ing the dif­fer­ent soil types that are rel­e­vant to wheat pro­duc­tion.”

Hochman says that other crops are just as likely to be af­fected by the snow­balling drop in po­ten­tial yield, though ad­verse ef­fects on the wheat in­dus­try would be par­tic­u­larly dev­as­tat­ing.

“Wheat is Aus­tralia’s most im­por­tant grain crop, but other im­por­tant grain crops like bar­ley, canola, and var­i­ous pulse crops that we grow all are likely to be sim­i­larly af­fected be­cause they will re­spond to the same cli­matic vari­ables in a sim­i­lar way.”

As well as be­ing par­tic­u­larly im­por­tant in Aus­tralia, a steady sup­ply of food is also a world­wide con­cern as in­creas­ing pop­u­la­tions and cli­mate change con­tinue to cause food short­ages in de­vel­op­ing na­tions.

Hochman says that even though a stronger pro­duc­tion of food in needed, cli­mate change could lead to a sig­nif­i­cant drop in wheat growth.

“By 2041, es­pe­cially those in ar­eas in which the [yield po­ten­tial] de­cline has been higher, there will be quite a few farm­ers who will find it too mar­ginal to keep grow­ing wheat,” he says.

“The World Food Or­gan­i­sa­tion has cal­cu­lated that, to meet the de­mand of grow­ing pop­u­la­tions and of a more af­flu­ent world, by 2050 the world is go­ing to have to pro­duce 60 per cent more food than it cur­rently pro­duces.”

CSIRO se­nior prin­ci­pal re­search sci­en­tist Dr Zvi Hochman

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