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Ground Cover and Weathering Effects on Reflectances of Three Crop Residues 1
Author(s) -
Wanjura D. F.,
Bilbro J. D.
Publication year - 1986
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1986.00021962007800040027x
Subject(s) - pennisetum , environmental science , weathering , panicum , agronomy , crop , crop residue , reflectivity , residue (chemistry) , chemistry , biology , ecology , paleontology , physics , optics , biochemistry , agriculture
Crop residue, which is important in protecting soil from wind and water erosion, is not easily differentiated from bare soil and difficult to quantify using remote sensing techniques. A field study was conducted on Amarillo fine sandy loam (Aridic Paleustalfs) for the purpose of measuring the change in spectral reflectance due to varying concentrations and weathering of Texas panicum ( Panicum texanum Buckl.) pearl millet [ Pennisetum americanum (L.) K. Schum], and cotton ( Gossypium hirsutum L.) bur residue. Reflectance was measured in seven wavelength intervals with a multiband radiometer (MMR). The greatest change in reflectance occurred between bare soil and 33% ground cover. Band MMR 2 gave the best separation between the crop residues. The MMR bands 1, 2, and 3 provided the best discrimination among fresh residue types; however, as weathering progressed after 240 mm of rainfall, reflectance in bands MMR 5, 6, and 7 was significantly different among residues. The ratio of MMR 5 divided by MMR 6 was < 1.0 for fresh crop residues compared with values > 1.0 after exposure to a 240‐mm rainfall. The largest relative change in reflectance during the weathering period among residues in decreasing order was pearl millet, Texas panicum, and cotton burs. Band MMR 4 showed the greatest relative reflectance change during 251 days of weathering. Detecting crop residue on bare soil with remote sensing techniques may be feasible if it is known whether the residue is fresh or weathered.