For Birchip, it's too early to pick a winner
GroundCover™ Issue: 48
Kay Ansell reports on a trial which is putting theories covered at the conference to the test.
Zero till versus conventional farming – which works best? The Birchip Cropping Group (BCG) is putting both to the test, along with two other farming systems, in a long-term trial.
Mirroring the fortunes of the grains industry, however, the drought has dramatically affected the financial results of the trial, which has run for four years and will continue for at least another two.
In 2002, only one system (conventional) harvested any crop and zero till has so far been the poorest economic performer – although this is only one of the sustainability yardsticks being measured.
In a joint paper analysing the trial, BCG farming systems economist Fiona Best reports that one of the biggest challenges for the trial and the farming community revolves around soil conservation versus moisture conservation.
She says this was evident in the drought year 2002 when many cereal crops grown on fallow yielded some return, while in the same year the Mallee soil suffered at the hands of severe wind and dust storms. In what is believed to be a first for the southern Mallee and northern Wimmera, the trial pits grower against grower in “championing” their chosen approaches.
By measuring physical production, economic performance and natural resource base sustainability, the trial aims to help growers decide which of the four approaches works best overall for dryland farming regions in the 300 to 450mm annual rainfall zone in Southern Australia.
The BCG believes the grower-driven nature of the project will encourage positive changes to farming practice to occur more rapidly. The four systems “championed” by their respective growers are:
The contestants share 20 hectares split into one hectare plots on the McClellands’ property, 30km north of Birchip. Crop intensity, livestock grazing and tillage are among the distinguishing characteristics of each.
Zero till has 100 percent crop intensity, no livestock, full stubble retention and one-pass, knife-point seeding. Reduced till has 80 percent crop intensity, minimum tillage and opportunity livestock.
Fuel burners is a conventional, cereal-based system with 60 percent crop intensity and opportunity livestock. Hungry sheep combines 70 percent crop intensity with intensive grazing by livestock.So far, the hungry sheep system has achieved the highest average gross margin.
The zero till system has had the greatest area sown to pulse and canola crops, sowing on average 50 percent of available area. This system also delivered the lowest four-year-average gross margin of $27.20 per hectare, while reduced till returned $125.70 per hectare and fuel burners “achieved” $142 per hectare.
Weeds, disease, nitrogen and soil water, and soil microbial activity are being monitored, along with soil compaction and organic carbon levels to determine the sustainability of each system in relation to the natural resource base.
“Despite early trends it would be impossible at this stage to suggest that one system is more superior than the others,” Ms Best says. It may take at least 10 years to know the long-term performance of each system, especially with regard to environmental aspects.
GRDC RESEARCH CODE BWD18, program 4
Region North, South, West