Andrew Erbacher1, Lindsay Bell2, David Lawrence3, Andrew Verrell4, Jon Baird4, Darren Aisthorpe3, Andrew Zull3, Jayne Gentry3, Greg Brooke4, Kaara Klepper5
1 Department of Agriculture and Fisheries, 22-26 Lagoon St, Goondiwindi, Queensland, 4390, firstname.lastname@example.org
2 CSIRO Agriculture and Food, 203 Tor St, Toowoomba, Queensland, 4350
3 Department of Agriculture and Fisheries, Queensland (Toowoomba and Emerald)
4 Department of Primary Industries, New South Wales (Tamworth, Narrabri and Trangie)
5 formerly 3Department of Agriculture and Fisheries, Toowoomba, Queensland, 4350
The efficiency of soil water accumulation during fallow periods, and the availability of that soil water for use by crops are key drivers of northern farming system productivity and profitabilityIn 2015 seven farming systems experiments were established from Central Queensland to Central NSW. Soil water, nitrogen and pathogens were regularly monitored along with crop biomass, grain yield and variable costs, as measures of system performance. A baseline cropping system, representing current commercial practice was established and tested against other systems with higher and lower crop intensity, higher crop diversity, greater inclusion of legumes in the rotation and higher fertiliser inputs. A key driver of northern farming system productivity and profitability is soil water accumulation during fallows periods for use by subsequent crops. We found that winter cereals and sorghum had the highest fallow efficiency (median 0.26), ahead of chickpeas (0.14) and canola (0.19). Short (4-8 months) and long (9-18 months) fallows following wheat had similar fallow efficiency, however lower fallow efficiency was recorded for sorghum stubble with longer fallows (0.33 vs 0.22) Changing cropping intensity had the greatest impact on fallow efficiencies, with increases in Higher intensity systems (0.37) and decreases in Lower intensity systems (0.16) relative to the Baseline (0.22). Varying fallow length has shown increased grain yield and water-use-efficiency for longer fallows, however rainfall use efficiency and gross margin/mm has favoured a 4-6 month fallow. Profitability favours a moderate intensity, with 0.8-1 crops/year providing the greatest return per mm of rainfall.