Soil and bean crop reflectances in the semi-arid region of the Northeast Brazil

This study presents the results of a field experiment conducted in the semi-arid region of the Northeast Brazil during the 1999 growing season. The crop selected is the bean crop (Phaseolus vulgaris L.)and the soil composition is 75.71% sand, 7,78% silt and 16,51% clay. The canopy reflectance measurements were made using a portable spectroradiometer (LI-1800). The data were collected at 2 nm intrervals and then integrated over the 20 nm intervals in the range of 300 to 1100 nm. In the visible part of the spectrum a peak reflectance of 0.089 was obtained at 560 nm for the bean crop under study. In the visible, the wet and dry soil reflectances were higher than the bean canopy reflectance. The dry soil reflectance was higher than the wet soil reflectance in the spectral region under study. The spectral signatures for the bean crop and the dry and wet soils are presented.