Farm Table says:
This research project between FarmLink, GRDC and CSIRO presents the following rules of thumb for managing N in stubble retained systems:
- Soil test in March-April
- If soil test results show less than 40 kg/ha N in the top 60 cm then apply some N at sowing. If there is more than 40 kg/ha mineral N then wheat and barley will make it to Zadoks stage Z30 (start of stem elongation) and canola will get to 6-leaf without losing yield potential.
- Top-dress the majority of N at Z30-31 (mid-July – early August) based on your best assessment of yield expectations. Add 40 kg/ha N per tonne of anticipated wheat grain yield, 80 kg/ha N per tonne of canola and 35 kg/ha N per tonne of barley. In SE NSW this can be done ‘by the calendar’ without waiting for a rain event.
- If conditions are favourable top-dress more N at Z39 in cereals (flag leaf emergence, early September) but at this time of year a rain after application is required to ensure plant uptake.
The remainder of the paper sets out clear and practical steps under the following headings:
- Soil Testing
- Soil Test Results
- Applying N at sowing
- Top Dressing
- N budgeting–N supply
- Putting it all together