| Studies were conducted to determine if four Mississippi agronomic crop residues and soils can be discriminated regardless of residue type, moisture content and decomposition level; and to compare the ability of published indices to quantitate known levels of wheat residue under realistic cropping conditions. A hand-held spectroradiometer was used to acquire hyperspectral data for corn, cotton, soybean and wheat residues and Marietta, Dubbs, Leeper and Dundee soils. Discriminant models were created for the data using multiple wavelengths. Results suggest the spectral reflectance of crop residues is dependent on the type of residue, moisture content and extent of weathering of the residue. Moisture content is the single most important factor when differentiating between different crop residues. Decomposition has less of an impact when differentiating residue types using hyperspectral reflectance. The cellulose absorption index (CAI) is the most functional index at this time for estimation of in situ crop residue cover, the areas of cellulose absorption appear to be the most useful spectral regions. However, the 1272 to 1304 nm region identified in this study does show some potential to overcome the water absorption issues associated with the CAI. |
