Frost pre-empted by research and experience
GroundCover™ Issue: 107 | Author: Rebecca Jennings
In the absence of a ‘silver bullet’, three growers explain how they combine experience with research to frost-proof their businesses.
Temperatures soar to 45°C in summer, but spring can be chilly at Tincurrin, Western Australia. Wade and Gerri Hinkley, who run a 4000-hectare mixed farm with Gerri’s father, Don Thomson, know the cost of waking up to a frosty morning.
“We had a really bad frost last September and lost 50 per cent yield in some paddocks,” Wade recalls.
It justified their decision three years ago to diversify into export hay. They baled the worst of the frosted wheat, tripling returns compared with areas of frosted crop left to harvest.
Although hay offers an alternative market and helps drought-proof their livestock, the family also relies on a ‘prevention’ strategy based on variety selection and management.
They start dry sowing lupins and oats in late April, followed by wheat in mid-May to capitalise on the seasonal break and minimise later frost risk.
The family usually runs two seeding units but this year, with soil moisture, temperature and weed burden combining for near perfect conditions, they limited seeding to 80ha/day to ensure varieties flower after the frost window in early September.
The long-season wheat variety Yitpi is planted first, followed by Mace and Kunjin – sown at 45 kilograms/ha with 100kg/ha of Agras Extra, which contains 16 units of nitrogen. They use a Flexi-Coil with 25-centimetre spacing, knife points and press wheels.
Wade and Don use the National Variety Trials (NVT) to select disease-resistant options that yield well in similar rainfall, and the Department of Agriculture and Food, WA, online tool Flower Power to identify varietal seeding dates to target optimal flowering.
Grazing stubble over summer maximises weed control, while grazing crops can manipulate flowering until after the frost risk period.
Other frost management strategies include:
- thermal imaging, which has identified a 3°C to 4°C difference in minimum temperatures between some paddocks, guiding where frost-sensitive varieties are planted;
- planting frost-prone paddocks last to help avoid the high-risk frost period;
- using paddock records to monitor frost history; and
- planting according to frost-prone areas, such as concentrating pasture crops and hay varieties on sandy zones and around creeks.
As president of the local Facey Group, Wade keeps a close eye on research. He is interested in early results from trials in the central and southern wheatbelt, which indicate stubble burning prior to seeding can reduce frost damage in wheat compared with stubble retention.
But Wade says his ideal frost-prevention toolkit would include a practical strategy to help make ‘hay or harvest’ decisions for frosted paddocks, rather than relying on visual assessment to gauge if crops are still growing.
Riverina growers the Hart family have made many on-farm adjustments in response to seasonal challenges, ranging from selling all livestock after the 2009 drought to focus on cropping, through to strategic crop management to minimise frost risk.
Today, Bernard and Anne Hart, their son Robert and his wife Alison farm 2000ha at Junee, NSW, and operate Hart Bros Seeds, a retail, production and distribution business established by Bernard and his brother Adrian in 1970.
With this history and a business mantra that ‘it all begins with seed’, it is no surprise the Harts are focused on variety selection and management to maximise returns in their environment, where heat and frost are the main production challenges.
Robert says while minor frost damage is expected each year, some years can be devastating – such as 1998 when they lost more than half the crop.
“We try to maximise yield by having wheat flower as close to 7 October as we can. In our environment this is the historical time where frost and heat stress meet.”
The topography of the farm, which features gently undulating red loam areas and creek lines, is a tool in frost-prevention.
“We now totally crop the lower, more frost-prone ground that requires slightly different management, as the ground is intrinsically colder, growth and development of wheat plants trend the same way. Using early sown, free-tillering varieties with vernalisation requirements helps to maximise growth and avoid frosting via delayed flowering.”
EGA Wedgetail and Whistler wheat meet these specifications, while for barley the Harts favour Hindmarsh for frost tolerance and yield.
The Harts feel decreasing moisture stress helps reduce frost risk. Stubble retention, a stringent summer spraying program and pre-emergent herbicides help achieve standard water use efficiency targets of 22 kilograms per millimetre of growing-season rainfall in cereals and 10kg/mm in canola.
Research, Robert says, is a key “input”, contributing to 80 per cent of the decisions made on-farm. The Harts build information gleaned from the GRDC, FarmLink, Grassroots Agronomy, research partners and CSIRO into business decisions.
On-farm seed trials, through the seed business, also present a first-hand opportunity to incorporate varieties and data on-farm.
“Each farming system is unique, so of course varieties will perform differently from farm to farm, and grower to grower,” Robert says. “It is important that growers test new lines of seed against varieties already in use in their system, and to trial the new variety in a small area to manage risk. We recommend growers have access to three varieties of wheat: an early-sowing, a mid-season and a late variety, to spread risk and to compare at least one of these each year against new cultivars.”
All Brian Gibson ever wanted was his own farm. After working on his family’s Darling Downs farm and contracted farming and harvesting across Queensland and northern NSW, he realised his dream in 1977 – buying an underdeveloped 280ha block at Dulacca on Queensland’s western downs.
Fast-forward 36 years and Brian, his wife Kaylene, their children Stephen and Ann Maree and son-in-law Matt Bach, now farm 6800ha around Dulacca.
“To manage the economic pressure of this expansion we are constantly looking for ways to increase productivity,” Brian explains from the cab of his dozer, while cleaning up a rocky paddock. “We have no set rotation; rather we are farmers of moisture. As soon as we have more than half a profile of moisture we plant another crop.”
The Gibsons are flexible with crop selection but tend to plant 60 per cent wheat, with rotations of barley, chickpeas, sorghum, mungbeans and, in the past, sunflowers and canola, to control weeds, crown rot and nematodes.
Severe frosts are common and can halve yields and drop quality from Prime Hard grade to Feed.
Over the past decade, Brian has observed a trend towards warmer weather from May to June, which induces wheat to head sooner, exposing it to frost risk in August.
“Thermometers at head height monitor minimum temperatures, giving us a good indication of where the frost line is. We plant above this line on the elevated country, which is usually 2°C to 3°C warmer than lower areas, and select slower varieties with a longer coleoptile length if we have to moisture-seek, as these will flower after the frost risk has passed.
The Gibsons host trials for the NVT program, providing a guide of suitable options for their area and production goals. This year, their wheat crop includes Suntop for the first time, as well as LongReach Spitfire, EGA Gregory and some Baxter – a combination selected to balance yield and protein.
With most big rain events in summer, the Gibsons rely on moisture-seeking strategies to plant early varieties in mid-April. Brian uses a Flexi-Coil with Janke no-till tynes and press wheels to plant chickpeas down to 15cm and wheat and barley to 5 to 7cm with a furrow to access soil moisture up to six weeks after rain.
When there is no frost damage, these early plantings produce more than 3.5 tonnes/ha compared with the overall farm average of 2.5t/ha.
Frosted crops are taken through to harvest to maintain ground cover and recoup some yield, although previous strategies included cutting crops for forage or slashing to try to get a regrowth.
Wade Hinkley, 08 9883 2063, firstname.lastname@example.org;
Robert Hart, 02 6924 7206; email@example.com;
Brian Gibson, 07 4627 6105, firstname.lastname@example.org
GRDC Project Code PFS36
Region North, National, South, West