Prophet may help profits with early data on yields

Kate MatthewsCountryman

A management tool used extensively by farmers in the eastern states to predict wheat yields as early as July is fast finding a following in the central and Great Southern Wheatbelt.

The model, Yield Prophet, was tested last year by the Department of Agriculture and Food WA (DAFWA) at 23 sites and will be rolled out again this season at another 20 sites.

DAFWA area manager for Narrogin and Lake Grace, Keith Devenish, said last year's successful trial was the first time the model had been tested widely in the region.

"The model was accurately able to predict wheat yields early in the growing season when growers were making expensive decisions about applying extra nitrogen and other crop inputs," Mr Devenish said.

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"To gauge its success, we want the predictions to be reasonably accurate in July and September, according to rainfall, and within 400kg of the farmer's final yield.

"We had 19 of the 23 sites close to the prediction and we found where the soil type didn't match well with those in the model's database, the yield predictions were less accurate."

The first predictions were run in July, when nitrogen decisions were being made by growers.

Mr Devenish said some growers decided to hold off on applying more nitrogen until further rain while others decided not to apply any extra at all.

"The YP model was reasonable accurate in predicting nitrogen availability and take up by plants as well as how much moisture was stored in the soil, and the daily take up rate by the crop plants.

"This means we could see how long the available moisture would last without rain, before yield was affected."

The model produced predicted yield range probabilities from 30 to 70 per cent in July and September and a final prediction in November.

"Information such as rainfall, soil moisture levels, eight day rain forecast, long range weather forecast, grain prices and level of risk are what each grower can consider once Yield Prophet produces its yield forecast," Mr Devenish said.

With seeding just around the corner, plans are underway for this season's network of trial sites.

Soil samples are being taken from this week onwards for analysis at sites near Cunderdin, Merredin, Bonnie Rock, Southern Cross, Corrigin, Brookton, Hyden, Nyabing, Lake Grace and Wickepin.

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