Rice nitrogen timing
Considerable scientific research over several decades has proven that applying nitrogen prior to permanent water for both aerial and drill sown rice is the most efficient practice, with panicle initiation applications running a close second. As we don’t have a rice soil nitrogen test and can’t predict seasonal temperatures, a split application between both timings is often the safest option, but what split is the best for yield and profitability?
- Sufficient nitrogen must be supplied to the rice crop from the soil and pre-permanent water fertiliser applications for adequate growth to be achieved by panicle initiation, or grain yield will be reduced regardless of how much nitrogen is applied at panicle initiation.
- When sufficient nitrogen was supplied pre-permanent water, there was no difference in grain yield between applying all the fertiliser nitrogen prior to permanent water or a split application with nitrogen also applied at panicle initiation.
- Due to increased potential for cold damage at high crop nitrogen levels, we recommend using the split nitrogen strategy. The majority of the expected required nitrogen should be applied prior to permanent water with a top-up at PI once soil nitrogen supply has been defined by crop growth.
- Gross margins are more sensitive to grain yield changes than changes in costs from variable nitrogen application timings.
Brian Dunn and Tina Dunn, NSW Department of Primary Industries, Yanco
IREC Farmers’ Newsletter – Large Area No. 191: Spring 2014. Read the full newsletter here.