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.
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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