Farm Table says:
The take home messages from this GRDC funded research are below. Please access the full paper via the link below for methodology, references, acknowledgements and discussion.
Take home messages from the paper include:
- The most important decision to consider when growing an irrigated wheat crop is whether it really needs to be fully irrigated. Deficit irrigation is often more profitable than full irrigation, and has the added bonus of being less likely to cause lodging.
- Lodging can drastically reduce wheat yield and cause difficulties at harvest. A package of agronomic measures should be used to reduce lodging risk including variety choice, irrigation strategy, N application strategy, plant population and Plant Growth Regulators (PGRs).
- Varieties respond differently to in-crop N application. Suntop, Wallup, Kennedy and LRPB Cobra often had higher yields when N was applied ‘in-crop’, but Mitch and LRPB Lancer did not. In-crop N application increased protein by 0.4% for most varieties and locations.
- PGRs gave the biggest yield response (0.6 t/ha) on well irrigated paddocks with more than 120 kg/ha of nitrogen available at sowing, when lodging was severe. However, PGRs still improved yield by 0.32 t/ha on high sowing N paddocks when there was little or no lodging. PGRs had a negative effect on yield for some varieties in an experiment that was only partially irrigated and experienced lower yields in the region of 5.5 t/ha.
- A guide to identifying lodging risk has been developed and is included in this paper. It is also detailed in Chapter 7 of the project publication ‘Better Irrigated Wheat Agronomy’ (Reference 1) which is available in hard copy here at the Goondiwindi Updates or from the authors. It can also be downloaded from the GRDC website at Better irrigated wheat agronomy North.
- All varieties have advantages and disadvantages for irrigated wheat production so please choose carefully after consulting the ‘Better Irrigated Wheat Agronomy’ publication (Reference 1) and the QLD and NSW variety guides. LRPB Cobra and Dart are the two most lodging resistant varieties for QLD and NNSW, but can still lodge under extreme conditions.
- Growers may achieve improved yield by using row spacings as narrow as 19cm (7.5 inches) compared to 28 or 38 cm (11 and 15 inches), but the results weren’t consistent across varieties and locations. Achieving a yield benefit from narrow row spacing was more likely when lodging was avoided.