THE latest WA yield ranking maps have shown one of the largest mid-season turnarounds in the State since they began 18 years ago.
Australian Export Grain Innovation Centre (AEGIC) agri-meteorologist David Stephens said during late-June yield rankings in much of the north-eastern wheatbelt were on track to be among the lowest 10 per cent to 30 per cent producing years.
However, falls of 50mm to more than 100mm at the end of July and early-August caused yield rankings to jump into the top 30 per cent of years, and in the case of Dalwallinu the highest 10 per cent in 100 years.
“The main reason for the yield improvement is that most of the rain fell slowly over a number of days and enabled the moisture to move down into the plant rooting zone and replenish drying soils,” Dr Stephens said.
“This reserve of soil moisture forms a ‘bank’ that crops can draw on through to the end of the season.”
When the AEGIC crop model STIN (moisture stress index) was run on July 27 and August 2, shire yield predictions increased by more than 0.7 tonne per hectare in Koorda and Quairading, and between 0.6-0.68t/ha in Bruce Rock, Dalwallinu, Goomalling, Mount Marshall, Trayning and Wonga Ballidu.
At a state level, the average wheat yields increased from 1.53t/ha to 2.02t/ha over the same interval of a week.
Some areas missed the rain and remained below average.