GROUNDBASED REMOTE SENSING OF WATER AND NITROGEN STRESS

Abstract

A groundbased remote sensing system (Agricultural Irrigation Imaging System, or AgIIS) was attached to alinearmove irrigation system. The system was used to develop images of a 1ha field at 1 1 m resolution to address issuesof spatial scale and to test the ability of a groundbased remote sensing system to separate water and nitrogen stress usingthe coefficient of variation (CV) for water and nitrogen stress indices. A 2 2 Latin square water and nitrogen experimentwith four replicates was conducted on cotton for this purpose. Treatments included optimal and low nitrogen with optimaland low water. ANOVA was not an adequate method to assess the statistical variation between treatments due to the largenumber of data points. In general, the coefficient of variation of water and nitrogen stress indices increased with water andnitrogen stress. In fact, the coefficient of variation of stress indices was a more reliable measurement of water and nitrogenstatus than the mean value of the indices. Differences in coefficient of variation of stress indices between treatments weredetectable at 3 m grid resolution and finer for water stress and at 7 m grid resolution and finer for nitrogen stress.