A LEADING agronomist has cautioned that the Bureau of Meteorology (BOM) forecast for a wet spring does not necessarily translate to a boost in yield.
The Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) has cited the favourable BOM spring outlook as one of the factors in its big upward revision in winter crop production.
However, Bob Freebairn, a veteran agricultural consultant based at Coonabarabran on NSW's north-west slopes, said that a blanket three month window for spring rainfall was too broad.
"The timing of that rainfall is critical, in north-west NSW you need that rain by mid-September or it can miss the window to be useful, especially if it has been a dry end to winter as it has this year," Mr Freebairn said.
"It could come in wet from then on and fulfil the criteria of being a wetter than average spring but it will not necessarily mean above average grain yields, the timing of the rain is all-important."
"All spring rain is not equal."
Mr Freebairn said there had been a slight tempering of expectations in north-western NSW over the past six weeks in terms of crop yields.
He said after the fantastic opening things had dried off and while there had been some August rain it was not enough to fully set crops up.
Mr Freebairn said yields were still set to be much improved on the past two years but said some of the topside yield was being lost due to the current lack of rain and the warm temperatures.
"It still looks very good and the roots are down into moisture so it is still likely to be an above average rain but the window for rain to really push those yields to exceptional levels is closing and there is little on the immediate forecast."
Mr Freebairn said it was a different story in more temperate climates further south towards the Central West proper, around Parkes and Forbes.
"They have had more rain and the temperatures have not been so warm so there is plenty of time for the weather patterns to line up and deliver some rain for crops there."
It is a similar situation in South Australia, where rain is urgently needed on the Eyre Peninsula in the next couple of weeks to maintain yield prospects.
The BOM's forecast have run into a stubborn glitch, similar to that seen in winter, where although the long term outlook is favourable for rain, in the short-term factors such as high pressure ridges have caused a halt to rainfall.
This type of phenomenon meant that in spite of the BOM forecasting a strong likelihood of a wet winter and overall good falls for the three month period in many areas some regions recorded their driest July on record.
Accuracy for BOM outlooks is better for spring is better than for winter so there is a reasonable amount of confidence about the outlook, which tips a markedly higher likelihood of wetter conditions for the eastern third of Australia, but if the rain comes later in the growing season it may be too late to be of full use.
However, one grains industry analyst believes things are still on track for a good season.
Lloyd George, AgScientia, said in spite of a modest season in Queensland and a tailing off of yield potential in north-west NSW it was still up to be a big season.
"We will see some loss of yield from northern NSW but it is only going to be around the margins, there is still going to be a lot of grain out there."
"I would suggest we're still on for decile 7 or 8 production that region and decile 9 or even better for much of the Central West, the Murrumbidgee and the Murray, so that yield boost from NSW, after very small winter crops the last two years, will really kick things along."
He said other states were looking generally solid, with the EP one of the poorer regions and eastern Victoria a bright spot.