34 IREC Farmers' Newsletter No. 198 — Spring 2017 Maize at Numurkah In the maize trial, there were two different irrigation schedules: l watered every 5 days at -30 kPa l watered every 7 days at -45 kPa. Each irrigation treatment was overlain by two nitrogen fertiliser treatments: l upfront – 70:30 (upfront: in crop) l split — 45:18:18:18 (upfront: in crop: in crop: in crop). Maize results In Year 1 of the maize trial (2015–16), establishment conditions were difficult with a 40 mm rain event just after planting, which had followed pre-watering. Grain yield was relatively low for the region at around 10 t/ha. Following a wet start, yield was influenced by nitrogen strategy and irrigation deficit (figures 3 and 4). In these conditions, yield was optimised by nitrogen application that was predominantly upfront and short irrigation deficits. In Year 2 of the trial (2016–17), establishment was good with more than 92,000 plants/ha. Overall there were no differences in nitrogen uptake at 7-leaf stage or at maturity. Grain yield was around 14 t/ha and improved by longer irrigation deficits and nitrogen fertiliser timing had no effect (figures 3 and 4). Maize conclusions Applying fertiliser upfront to maize generally increased yield compared with split fertiliser application in both years, when growing conditions provided low and high yield potential. Nitrogen uptake rates were no different at different growth stages for the different irrigation and nitrogen timing strategies. The data suggests predominantly upfront fertiliser application may be possible without yield penalty or reduced nitrogen use efficiency, which potentially could decrease labour costs and trafficking of the field. Ray Thornton (left), co-operator for the maize trial, explaining crop management during the second year of the trial. 0 2 4 6 8 10 12 14 Split Upfront 2015-16 2016-17 Figure 3. Grain yield of maize at Numurkah, as influenced by nitrogen management over two cropping seasons. Nitrogen management strategy Grain yield (t/ha) Figure 4. Grain yield of maize at Numurkah, as influenced by irrigation management over two cropping seasons. 0 2 4 6 8 10 12 14 -45 kPa -30 kPa 2015-16 2016-17 Irrigation deficit Grain yield (t/ha) Acknowledgements The Maximising on-farm irrigation profitability project is conducted by NSW DPI and CeRRF, Deakin University in conjunction with the three regional irrigation grower groups — Irrigated Cropping Council, Southern Growers and Irrigated Research and Extension Committee. Each of the grower groups hosts field experiment sites for the project, which are key sites for the extension of project findings. Organisations such as Local Land Services, CottonInfo and Rice Extension are also involved in project extension. The project is supported by funding from the Australian Government Department of Agriculture and Water Resources as part of its Rural R&D for Profit Programme, the Cotton Research and Development Corporation and the Rural Industries Research and Development Corporation. James Hill, Point Farms, Darlington Point and Ray Thornton, Yalca (near Numurkah), are sincerely thanked for their co-operation. Further information Wendy Quayle Senior Research Fellow T: 0417 436 775 E: [email protected]