Field‐measured Spectroradiometric Reflectances of Disked and Nondisked Soil With and Without Wheat Straw

Our objective was to compare field‐measured spectroradiometric reflectances of nondisked bare soil with or without littered wheat ( Triticum aestivum L.) straw and bare soil that was disked directly or after littering with wheat straw. This information is needed to develop a procedure for predicting potential soil erosion using aircraft or satellite multispectral scanner reflectance measurements. A ground‐based spectroradiometer was used to measure reflected radiation from six soil‐tillage‐wheat straw treatments: disked and nondisked soil with and without two wheat straw rates—equivalent to 2.24 and 4.48 metric tons/ha, respectively. The near‐infrared region (0.75 to 1.3 µm), exemplified by the 1.05‐µm wavelength, seemed to be better than the visible region (0.45 to 0.75 µm) or water absorption wavebands (1.5 to 1.8 µm and 2.0 to 2.5 µm) for distinguishing among reflectances of the soil‐tillage‐straw treatments. Results indicated that LANDSAT multispectral scanner's band 7 (0.8 to 1.1 µm) might be used to distinguish nondisked bare soils from those with different amounts of straw on their surface, but not to distinguish reflectance of nondisked bare soils, disked bare soils, and disked soils with small amounts of straw incorporated in them. Further research is needed on the interacting effects on reflectance of other soils, soil moisture contents, kinds and amounts of plant residue, tillage operations, and their interactions on reflectance.