Rice PI nitrogen - how much yield can I gain?
We apply nitrogen fertiliser to rice at panicle initiation (PI) as a top up for any shortfall from soil nitrogen supply and pre-permanent water applied nitrogen fertiliser. Applying nitrogen at PI is relatively efficient and you can adjust the amount required depending on the crop’s growth, but how much can grain yield be increased by applying nitrogen at PI?
- The maximum grain yield increase obtained from PI nitrogen topdressing was 2.8 t/ha and this was at a very low PI nitrogen uptake.
- At a PI nitrogen uptake of 100 kg N/ha, grain yield was only increased by 0.7 and 1.0 t/ha when 60 and 120 kg N/ha (130 and 260 kg/ha urea) was applied respectively.
- Sufficient nitrogen must be supplied from the soil and pre-permanent water applied nitrogen to reach a PI nitrogen uptake of 100 kg N/ha or grain yield potential will be reduced.
- If a PI nitrogen uptake of 100 kg N/ha is not going to be reached by PI it may be necessary to apply nitrogen at mid to late tillering to ensure a satisfactory grain yield is achieved.
Brian Dunn, NSW Department of Primary Industries, Yanco
IREC Farmers’ Newsletter – Large Area No. 191: Spring 2014. Read the full newsletter here.