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Title: GROUND-BASED REMOTE SENSING OF WATER AND NITROGEN STRESS

Author
item KOSTRZEWSKI, M - UNIV OF ARIZONA TUCSON AZ
item WALLER, P - UNIV OF ARIZONA TUCSON AZ
item GUERTIN, P - UNIV OF ARIZONA TUCSON AZ
item HABERLAND, J - UNIV OF ARIZONA TUCSON AZ
item COLAIZZI, P - UNIV OF ARIZONA TUCSON AZ
item BARNES, EDWARD
item THOMPSON, T - UNIV OF ARIZONA TUCSON AZ
item CLARKE, THOMAS
item RILEY, E - UNIV OF ARIZONA TUCSON AZ
item CHOI, C - UNIV OF ARIZONA TUCSON AZ

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2003
Publication Date: 1/15/2003
Citation: KOSTRZEWSKI, M., WALLER, P., GUERTIN, P., HABERLAND, J., COLAIZZI, P., BARNES, E.M., THOMPSON, T., CLARKE, T.R., RILEY, E., CHOI, C. 2003. GROUND-BASED REMOTE SENSING OF WATER AND NITROGEN STRESS. TRANSACTIONS OF THE AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS. 46(1):29-38.

Interpretive Summary: The increased use of new tools to precisely control the amount and location of agricultural inputs has created a need to map crop conditions with more detail than in the past. Some of the information required by farmers to make management decisions can be derived from remotely-sensed data, and these data are typically more cost effective than destructive soil and plant sampling. The cost and processing time for remotely-sensed data decreases as spatial resolution increases; therefore, finding the minimal spatial resolution required for different management objectives is important. This study was conducted to investigate the effect of spatial resolution on the ability to detect water and nitrogen stress in a cotton crop with a ground-based sensor. The results of this study indicated that it was possible to map crop nitrogen status at a spatial resolution of 10-m without loss of information at this particular study site. The spatial resolution for water stress detection appeared to be finer; however, all of the variations due to changes in weather conditions during data acquisition were not accounted for and further study is needed. The results of this study will help equipment and satellite companies developing sensor systems with information on what spatial resolution is needed for agricultural management. The findings also will be of use to other scientists investigating spatial variability in crop production and input requirements.

Technical Abstract: A ground-based remote sensing system (AgIIS, Agricultural Irrigation Imaging System) was attached to a linear move irrigation system. The system was used to develop images of a 1-hectare field at 1x1 meter resolution. A 2x2 Latin square water and nitrogen experiment with four replicates was conducted on cotton in order to test the ability of the remote-sensing system to separate water and nitrogen stress using the coefficient of variation for water and nitrogen stress indices. Treatments included optimal and low nitrogen with optimal and low water. Field images were collected over the entire 1999 growing season, and four days of field images were selected for the analysis. Nitrogen stress was evaluated from a canopy chlorophyll content index while water stress was evaluated from the difference between canopy and air temperature. Images of the plots were constructed based on the 1x1 m data in order to evaluate the spatial scale required to detect early onset of water and nitrogen stress based on coefficient of variation of the indices.