Diffuse-Reflectance Mid-infrared Spectral Properties of Soils under Alternative Crop Rotations in a Semi-arid Climate
2011
Calderón, Francisco J. | Mikha, Maysoon M. | Vigil, Merle F. | Nielsen, David C. | Benjamin, Joseph G. | Reeves, James B III
We carried out mid-infrared (mid-IR) spectral interpretation of soils 0-5 and 5-15 cm deep in selected alternative crop rotations (ACR) treatments and an adjacent native prairie soil. Ashing and spectral subtraction shows that absorbance at 3700-2850 and 1700-1550 cm-1 indicates organic absorbance. Prairie soils, with their greater carbon (C) content, have different spectral properties from the cropped soils. Prairie soils have greater absorbance at the 2950-2870 cm-1 and the 1230 cm-1 CH bands. The soils from the different depths had different spectral properties, with the soils 0-5 cm deep having stronger absorbance at the 1055 cm-1 carbohydrate band, at 1270-1460 cm-1, and at the 1730 cm-1 ester band. The soils 5-15 cm deep are characterized by greater absorbance at the clay band. Soil C and nitrogen (N) correlated negatively with the 3700 cm-1 clay band and the 1830 cm-1 quartz band and correlated positively with the 2920 cm-1 because of aliphatic CH absorbance.
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