Landholders adjust programs in response to season forecast
Department of Fisheries
自动标签： grainbelt cent rainfall season soil chance nitrogen Department average forecast
Seeding is underway across the grainbelt, as broadacre producers adjust their cropping programs in response to a patchy start to the 2019 growing season and predictions for continued dry conditions.
The Department of Primary Industries and Regional Development’s Statistical Seasonal Forecast (SSF) for the next three months has an overall prediction of a drier than normal season, with some variable predictions for different regions.
The SSF indicates the chances of exceeding median rainfall between May and July is less than average (40 per cent) in the northern and southern grainbelt, more favourable (60 per cent) in the far eastern areas and the shires of Ravensthorpe and Esperance, and neutral (40-60 per cent) elsewhere.
Confidence in the prediction varies from poor to good (50-75 per cent consistent).
The most probable rainfall decile range is 2-3 for the northern and southern grainbelt, 8-10 for Ravensthorpe and Esperance, and 4-7 elsewhere.
The Bureau of Meteorology’s seasonal outlook for the same period in the grainbelt is for a 30-70 per cent chance of exceeding median rainfall, with a lower chance (30-45 per cent) in southern parts of the northern grainbelt, western central grainbelt and the South West and a higher chance (60-70 per cent) in the Esperance and Ravensthorpe shires, based on a similar predictive skill.
The Bureau’s temperature outlook for May to July indicates a 50-75 per cent chance of above average day time maxima for the grainbelt, based on a mostly good predictive skill, while it suggests a 50-70 per cent chance of above average night time minima, based on mostly poor predictive skill.
Department research officer Meredith Guthrie said the SSF outlook for May to October was similar to the three-month outlook.
“Combining seasonal outlooks with multi-week rainfall forecasts suggests the 2019 growing season is likely to have a late break, and will be similar to last year for many districts,” Dr Guthrie said.
“Other climate models indicate drier conditions for much of the grainbelt, with the possibility of a positive Indian Ocean Dipole by September, which could reduce the chances of good finishing rains.”
The department’s plant available soil water maps show stored soil moisture levels are extremely low across much of the grainbelt except for parts of the south coast.
Research officer Jeremy Lemon said growers across much of grainbelt were considering modifying their sowing program in response to low soil water and the late start to the season, by changing crops and reconsidering the use of poorer paddocks.
Mr Lemon said nitrogen fertiliser applications would also require review during the season and advised growers to closely assess their yield potential, stored soil water levels and weather forecast when deciding how much to apply and when.
“Department research has shown top-up nitrogen for canola in low and medium rainfall areas can be delayed until the start of flowering, about 12 weeks after sowing, without reducing yield,” he said.
“Following a small starter nitrogen application at seeding, top-up nitrogen for barley and wheat should be delayed to the late tillering or early stem elongation stage.
“This delayed nitrogen does not reduce yield, while often providing higher grain protein.”
Pasture growth rates have also been varied across the grainbelt, as shown by weekly Pastures from Space feed on offer (FOO) maps, now available for free from the department’s Season 2019 webpage.
Department veterinary officer Danny Roberts encouraged livestock producers to adjust their feed budgets in line with the seasonal forecast as well as taking into account the amount of green pasture, as it becomes available.
“The FOO maps suggest the vast majority of livestock producers across the agricultural region could well be supplementary feeding until July,” Dr Roberts said.
DPIRD’s Statistical Seasonal Forecast for the next three months is for below average rainfall for most of the grainbelt, except for parts of the far east, the south east coast and the South West, where the prediction is more favourable.
With low stored soil water levels and below average rainfall forecast for much of the grainbelt, DPIRD has warned growers to reassess their cropping programs and feed budgets.
Pastures from Space FOO and pasture growth maps, like the one shown, are available on the department’s Season 2019 webpage, updated weekly.
Jodie Thomson/Megan Broad, media liaison
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