Broadcast seeding: try a bit
GroundCover™ Issue: 35
Broadcast seeding has kept us farming, says Ben Hughes of ‘Wangabina’, north-east of Ceduna on the Eyre Peninsula.
Mr Hughes, on marginal sandy loam country that borders the famous dog fence where cropping stops and the natural mallee country continues, says broadcasting is a low-cost — compared to other tillage methods — option that’s good for the soil and suits his one-man operation. Average rainfall at ‘Wangabina’ is 307 mm and the rains often don’t contribute much until late in the season.
Broadcast seeding was developed by Bob Holloway and colleagues at the Minnipa Agricultural Centre and, in trials there for the past 18 years, yield and gross margin have consistently outstripped other tillage methods. Nevertheless, adoption has been timid with a few exceptions like Mr Hughes who now sows his whole farm in this fashion.
Low rainfall prods try
He recalled how five years ago Bob Holloway visited the Hughes farm in May, after 6.5 mm had fallen, dampening the top 4 cm of topsoil, “not a seeding option with our combine”. However, there was a paddock where the grass had been sprayed out the year before and Dr Holloway suggested they broadcast wheat on it. “We thought Bob had been out in the sun without a hat for too long.” Try a bit, urged the researcher, explaining the Minnipa trial results.
“So we broadcast 160 acres, liked the results, and have been increasing the area ever since.” These days he broadcasts a choice of four varieties across 809 hectares (2,000 acres), selecting the varieties for their later maturity and frost hardiness, as well as marketability. “Our yields with this method are significantly higher because it allows us to go seeding on much lower rainfall, taking advantage of all the rain that comes in the growing season.”
Making machinery and saving on inputs
Ben Hughes helped himself to succeed by making an appropriate technology prickle-chain seeder combination, an adaptation that cost him a mere $10,000 rather than $200,000 for a new tillage system.
He uses a five-tonne Jetstream spreader with twin hydraulic spinners, which easily throw 20 metres. A prickle chain is towed behind to cover the grain. Mr Hughes adapted the frame to carry two chains going to the rear on both sides (as distinct from a diamond chain).
“We found you need to run the chain over the grain twice — hence one chain following the other. A separate small chain is placed to cover where they join at the rear.
“Seed and super are combined in the spreader, making it a one-pass operation, pulled by a 110-horsepower tractor. It’s much faster than a 40-row combine and cheaper on fuel as well.”
Weed control key to the system
The key to the whole concept, according to a research report in the Eyre Peninsula Farming Systems (EPFS) 2000 Summary, is very effective weed control (especially barley and ryegrass) the season or two before. With five years using the system under his belt, Mr Hughes agrees.
Effective weed control supports early establishment, regardless of the system. “The trick is to get in early before the winds start,” he says.
Broadcast seeding, say the researchers, may not suit the whole farm, depending on soil type and rainfall. Its major benefit in low-rainfall situations is the ability to sow a lot more ground during the short period when top-soil is Ben Hughes in a field of Excalibur: “If you want broadcast seeding to work, it will. I took the view that I had nothing to lose.” In trials published in the EPFS 2000 research summary.
Mr Hughes sowed at 60 kg/ha (district practice). His growing season rainfall was 241 mm. His sowing rate was roughly 40 per cent lower than most of the other farmers who joined the trials. However, he seeds his whole operation this way while the others were trialing a couple of paddocks. Final average yield was 1.2 t/ha, which was 33 per cent above his average grain yield.
Core site results
The Minnipa research centre paddocks with 298 mm growing season rainfall served as a yardstick for the system. They were sown at 110 kg/ha on 10 May following a chemical fallow the year before; summer weed control and fertiliser pre-drilled early April. The machinery used at Minnipa was a Gason Bar with narrow tungsten tip cultivator point on 23 cm spacings for pre-drilling fertiliser and Marshall single-spinner, 3.5-ton spreader for the seeding operation, followed by a prickle chain in a separate pass.
Average yields of Frame, Bt Shomburgk and Camm were 2.13 t/ha.
Contact: Mr Ben Hughes 08 8625 8013;
Dr Bob Holloway 08 8680 6207
Take-home messages on broadcast seeding
- quick low-cost option for low-rainfall, lighter soils areas
- maximises use of available water
- gets crop in very quickly on small rainfall events
- quick germination in wet band near soil surface
- higher seeding rate for grass competition
- pre-drilling fertiliser boosts success.
A couple of pointers from the EPFS 2000 economic evaluation of seeding methods: broadcasting allows sowing large areas quickly on opening rainfall, with little capital investment in equipment. If you have the necessary equipment, no system is always right or wrong; it depends on the seasonal conditions at the optimum sowing time. Sowing successful cereal crops on sandy soils is nine-tenths agronomy and timing and one-tenth how you actually place the seed in the soil.