FEARS have been raised CBH Group may have "undercooked" segregation preparations at its receival sites, with predicted yields from farmers around the State exceeding what CBH has anticipated in some cases.
In the Shire of Victoria Plains, current estimates from CBH for the Calingiri bin catchment were 2.9 tonnes per hectare for wheat, 3.25t/ha for barley and 2t/ha for canola.
Calingiri farmer Steve Woods is expecting at least 4t/ha for wheat and barley and definitely more than 2t/ha for canola.
That is a 20 to 25 per cent increase on the long-term average yields.
It's a similar story for Bolgart farmer Julian McGill who will be delivering grain to the Calingiri receival site.
"I'm quite concerned that CBH operations have grossly underestimated the Shire of Victoria Plains yields leading into this harvest," Mr McGill said.
"Many Victoria Plains growers will outperform last year's record season and I feel the estimate of 200,000t for Calingiri is well undercooked considering Calingiri received well over 240,000t last year.
"I'm also very concerned the Piawanning bin will be in a 'full and shut' situation, which will add even more tonnes to be delivered to Calingiri."
For CBH, Paddock Planner plays a critical role in understanding the amount of hectares growers have planted and are expecting to deliver to a particular site, with that information used to inform services and segregations for harvest and plan emergency storage if needed.
When it comes to converting the information from Paddock Planner into estimated yield, CBH gathers a range of known datasets to measure and predict yield, such as soil moisture, rainfall and Normalised Differential Vegetation Index (NDVI) imagery.
"We then use that information, in conjunction with known crop types and locations provided from Paddock Planner, to form an estimate of the yield for each crop type," said CBH chief operations officer Mick Daw.
"In addition to this, CBH takes into consideration grower feedback about the yields they are expecting throughout the season.
"The combination of these sources of information are then benchmarked and weighed against external publications of crop estimates, such as GIWA (Grain Industry Association of WA)."
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In the eastern Wheatbelt, Bruce Rock farmer Leigh Strange couldn't remember exactly what CBH provided at the local bin meeting in terms of yield estimates, but he was confident growers would produce more than what the co-operative had anticipated.
"That's on the back of the fact we've had such a cool, mild finish with no frost," Mr Strange said.
"We're going to see some surprises, particularly in wheat, and there are going to be some headaches for CBH because of that."
One of the most tried and tested ways of figuring out potential yield is the French and Schultz calculation which is based on determining water use efficiency.
Essentially, the equation works on the idea that a wheat crop will yield 20 kilograms of grain per hectare per millimetre of effective growing season rainfall.
According to Crop Circle Consulting and Research director Grant Thompson, that number of kg/mm can vary wildly.
"The timing of the rainfall is most important because if a grower gets rain during the grain fill period, it's highly effective at going into yield and can change the water use efficiency significantly," Mr Thompson said.
"Most of the State has had a very mild and gentle finish, so I would expect water use efficiency would be very good this season."
Mr Daw implored growers to fill out Paddock Planner in the future as it provided the co-operative with better data that allowed CBH to plan more accurately and provide a better service.
"When a grower doesn't submit their crop estimates, there is greater uncertainty around what services and segregations are required for a site," he said.
"Last year, actual grain deliveries at some sites were up to three times more than what had been submitted through crop estimates, resulting in storage shortfalls and impacting services to growers at those sites.
"In addition to the yield estimate, Paddock Planner plays a critical role for CBH to understand the total amount of hectares growers are expecting to deliver to a site, and those two pieces of information together give us a view on the expected receivals to site."
