From the report «Comparison of crop canopy reflectance sensors used to identify sugarcane biomass and nitrogen status», of Lucas R. Amaral, José P. Molin, Gustavo Portz, Felipe B. Finazzi, Lucas Cortinove, published at Precision Agric (2015) 16:15–28
Canopy reflectance sensors are useful tools for guiding nitrogen fertilization in crops. Four nitrogen (N) rate experiments were conducted (plots), along with biomass sampling, chlorophyll meter readings and leaf N concentration determination in another four fields by canopy sensor readings guided samplings. Neither of the canopy sensors showed a correlation with the obtained chlorophyll meter readings (SPAD) or leaf N content within the fields, while high correlations with above-ground biomass were found, indicating that the plant population and vigor interfered with the canopy sensor readings. Regardless of the canopy sensor and wavebands used, all of the analyzed sensors proved to be good tools for identifying the variability of crop development in sugarcane fields.