For paddocks that missed out on this year's winter crop because of wet conditions during sowing, sunflowers are a worthwhile early sown summer crop option.
Because of relatively low crop residue levels and a high probability of harvesting well before sowing time for the 2023 winter crop, it can be a good fit. Sunflowers suit sowing earlier than grain sorghum.
Reports suggest that because of the war in Ukraine, traditional suppliers of much of the world's sunflower needs, demand should be good. However, it is advisable to check potential buyers for likely prices.
Sunflowers were once a popular crop over much of the NSW north-west with reasonable areas well into the Central West and Murrumbidgee Irrigation Area.
The decline was not because the crop was difficult to grow, but more due to competitive returns from alternate crops such as grain sorghum, maize, mung beans and cotton.
Sunflower plant breeders have developed good varieties and provided price prospects are good, we could easily produce a sizable Australian crop once again.
Minimum soil temperature requirements for sunflower germination are 10-12 degrees, taken at 10cm depth at 8am. While there is a trend to sow sorghum on cooler soils than previously considered standard practice, sunflowers have a clear advantage in early sowing and for a quick crop well ahead of next year's normal winter crop sowing.
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The critical time for heat stress is 12-15 days after the beginning of flowering, for many areas, around 70 to 100 days depending on temperature, variety maturity and how early one sows.
In hotter north western areas, farmers have tended to sow early or late, to help avoid flowering in the hottest period, generally January to February. However, heat waves are unpredictable and can occur from November to March therefore, heatwave risk can never be totally avoided.
Sunflowers have a deep taproot which can extract moisture from up to 3m deep in ideal soil conditions and have a higher soil water extraction ability than many other crops, including sorghum and maize. Like for all summer crops, prospects will be best in deep soils with no sub-soil constraints like sodicity, acidity, or single elements like chloride or hardpans. Good levels of stored soil water are important.
Despite a small current Australian Sunflower industry, past breeding programs, plus their international links, have resulted in a good range of varieties for NSW areas likely to grow the crop.
It is important to know what market one is aiming for as there are varieties for various ones, including human consumption, birdseed, and specific as well as general oilseed use.
Varieties have been developed with rust and Alternaria resistance, combined with current commercial tobacco streak virus tolerance. Varieties have also been developed with tolerance to Intervix herbicide, a big plus for weed control.
Sunflowers are sensitive to several residual herbicides, including sulfonylureas. It is important to check on plant back period, generally affected by aspects such as time since application, soil type, herbicide rate and rainfall.
The targeted plant population for sunflowers varies from hotter, drier districts to milder higher rainfall zones. The range suggested is 25,000 to 35,000 plants per hectare.
The seed has germination percentage and number of seeds per kilogram marked on each bag. When calculating seed requirements, allow on average 25 per cent for establishment losses.
Sunflowers require good soil fertility, but not excessively so. Nitrogen is critical, but excessive soil levels can downgrade seed oil content.
Typically medium soil fertility levels will respond economically to 40 to 80kg/ha nitrogen fertiliser. Because sunflowers are generally sown in wide rows (0.3m to 1m wide rows), most fertiliser needs to be placed slightly away from the seed at sowing.
Sunflower Best Management Practice Training Courses, presented by the Australian Sunflower Association, providing the latest information, will be held at Coleambally on August 23 and Griffith on August 24. For details and booking, contact Phil Bowden, Pulse Australia 0427 201 946 phil@pulseaus.com.au
Next week: Good and bad under dry grass pasture.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact (0428) 752 149.
