Progress in remote sensing of PI nitrogen uptake

The ability to measure real-time crop characteristics is allowing improved nitrogen management during the season, giving potential to increase productivity and profitability in the rice industry.

Quick take:

  • NDVI is of limited value in detecting differences in nitrogen uptake in rice crops at panicle initiation (PI) due to its saturation at nitrogen uptake levels above 80 kg N/ha.
  • NDRE uses wavelengths in the red edge band and it provides a stronger relationship with nitrogen uptake in rice at PI than NDVI.
  • A preliminary calibration has been developed for the MicaSense RedEdge sensor to directly predict PI nitrogen topdressing rates for Koshihikari, Doongara and YRK5 rice varieties using NDRE values, without the need to physically sample the crop.
  • Rice varieties requiring nitrogen topdressing at higher levels of PI nitrogen uptake, will still require physical sampling of the crop at PI to determine PI nitrogen uptake.

Brian Dunn & Tina Dunn, NSW Department of Primary Industries, Yanco Agricultural Institute, Remy Dehaan, Charles Sturt University and Andrew Robson, University of New England

IREC Farmers' Newsletter No. 198 — Spring 2017. Read the full newsletter here.