RapidSCAN is a new portable active crop canopy sensor with three wavebands in red, red-edge, and near infrared spectral regions. The objective of this study was to determine the potential and practical approaches of using this sensor for non-destructive diagnosis of rice nitrogen (N) status. Sixteen plot experiments and ten on-farm experiments were conducted from 2014 to 2016 in Jiansanjiang Experiment Station of the China Agricultural University and Qixing Farm in Northeast China. Two mechanistic and three semi-empirical approaches using the sensor's default vegetation indices, normalized difference vegetation index and normalized difference red edge, were evaluated in comparison with the top performing vegetation indices selected from 51 tested indices. The results indicated that the most practical and stable method of using the RapidSCAN sensor for rice N status diagnosis is to calculate N sufficiency index with the default vegetation indices and then to estimate N nutrition index non-destructively (R2 = 0.50-0.59). This semi-empirical approach achieved a diagnosis accuracy rate of 59-76%. The findings of this study will facilitate the application of the RapidSCAN active sensor for rice N status diagnosis across growth stages, cultivars and site-years, and thus contributing to precision N management for sustainable intensification of agriculture.
Bibliographical noteFunding Information:
This study was financially supported by the Key National Research and Development Program (2016YFD0200602), National Basic Research Program (2015CB150405), the Innovative Group Grant of Natural Science Foundation of China (31421092) and the Sino-Norwegian Cooperative SINOGRAIN project (CHN-2152, 14-0039). The kind assistance and supports provided for this research by Yuan Gao, Wen Yang, Yong Yang, Haisheng He, Honglin Li, Fengyan Liu and Xiaolong Wang at Jiansanjiang Institute of Agricultural Research and Jiansanjiang Branch Bureau of Agricultural Reclamation and Mr. Guojun Li from Jiansanjiang Department of Agriculture are highly appreciated.