|Corp, Lawrence - NASA/GSFC, GREENBELT, MD|
|McMurtrey Iii, James|
|Mulchi, Charles - UNIVERSITY OF MARYLAND|
|Chappelle, Emmett - NASA/GSFC, GREENBELT, MD|
|Kim, Moon - NASA/GSFC, GREENBELT, MD|
Submitted to: Remote Sensing of Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 8, 1998
Publication Date: N/A
Interpretive Summary: Techniques to assess nitrogen supply in crops are needed to implement precision farming methods in modern agriculture. Application rates of nitrogen could be adjusted if precise detection methods could determine nitrogen status in a developing crop. A technique using actively induced fluorescence shows promise as a remote, non-destructive method to monitor plant productivity as it relates to plant nitrogen levels. Optimal rates of fertilization per specific field site could be applied. This technique could prevent over and under supply of nitrogen fertilizers to crops.
Technical Abstract: Leaf level fluorescence measurements were explored as a non-destructive, remote means to monitor plant productivity changes in field grown corn (Zea mays L.) as they relate to varying levels of nitrogen (N) fertilization. Nitrogen was supplied in the form of urea at varying rates to obtain levels corresponding to 150, 125, 100, 75, 50, 25, and zero percent of the nitrogen required for optimal growth. The recommended rate of nitrogen fertilization on the field site was determined to be 162 kg N/hectare. The field site consisted of seven nitrogen treatments in four randomized complete blocks. Fluorescence spectral measurements were obtained from the uppermost fully expanded leaves at the grain fill stage of growth. Fluorescence measurements were compared with the following physiological parameters: rate of photosynthesis, elemental composition, pigment and protein concentration, and grain yield. Leaf level fluorescence emissions as they relate to physiological changes within the plant in response to nitrogen supply were characterized. This research is directed toward providing a remote, non-destructive technique to distinguish inadequate and excess fertilization of corn crops with nitrogen fertilizers.