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Kang Yu, Fellowship grant 2014

Hyperspectral Remote Sensing of Crop Canopy Chlorophyll and Nitrogen

I appreciate very much the fellowship grant program of the Graduate School of Geosciences (GSGS), University of Cologne. I was supported by the GSGS Fellowship Grant during the very final phase of my PhD study, which was focused on modelling crop canopy chlorophyll and nitrogen content with hyperspectral remote sensing data. Remote sensing has been used for a wide range of agricultural applications, and it has been proven to be a powerful tool for investigation of agricultural land-use change and for mapping crop growing area at large scales. In agriculture, precise crop management requires a precise assessment of the within-field variability of crop growth in a dynamical and timely manner, raising the need for quantitative understanding of the link between canopy hyperspectral data and biological processes. However, crop canopy structural characteristics and plant morpho-physiological variations in different growth stages add to the understanding of such connections, as well as remote retrieval of canopy biochemicals such as chlorophyll and nitrogen, which function as important indicators of plant health. The changes in a crop canopy and the nitrogen dilution effect occurring within a plant with the advance of growth stages lead to adverse effects on remote estimation of nitrogen. Accordingly, new methods and models have been developed in my PhD project to improve the modelling of crop chlorophyll and nitrogen content for different growth stages through the use of the dynamical inter-correlations between plant biomass and nitrogen in different growth stages. The new methods for optimizing vegetation indices have been proved to be very efficient for improving the accuracy of remote retrieval of canopy chlorophyll and nitrogen. The GSGS Fellowship Grant enabled me to complete the revision work of two manuscripts for peer-reviewed journal publications and co-author a manuscript with my colleagues. Also, during the grant period, I applied successfully for a postdoc position at the ETH Zurich to expand my research skills, which could not have been possible without the fellowship grant that supported my stay in Germany. Finally, I would like to thank again gratefully acknowledging the fellowship grant from the GSGS of the University of Cologne, and I believe that the GSGS grants will achieve a great success in fostering young researchers.


Kang Yu

Institute of Geography

GIS & Remote Sensing Group, Prof. Dr. Georg Bareth

PhD project: Hyperspectral Remote Sensing of Crop Canopy Chlorophyll and Nitrogen

Defense: April 2014

Thesis title: Hyperspectral Remote Sensing of Crop Canopy Chlorophyll and Nitrogen: The Relative Importance of Growth Stages

Journal publications during the grant period:

Yu, K., Gnyp, M.L., Gao, L., Miao, Y., Chen, X., & Bareth, G., 2015. Estimate Leaf Chlorophyll of Rice Using Reflectance Indices and Partial Least Squares. Photogramm. Fernerkund. Geoinf. 2015 (1): 45-54. DOI 

Yu, K., Lenz-Wiedemann, V., Chen, X., & Bareth, G., 2014. Estimating leaf chlorophyll of barley at different growth stages using spectral indices to reduce soil background and canopy structure effects. ISPRS J. Photogramm. Remote Sens. 97: 58-77. DOI