Abstract
| Original language | English |
|---|---|
| Pages (from-to) | 171-180 |
| Number of pages | 10 |
| Journal | Geoderma |
| Volume | 152 |
| Issue number | 1-2 |
| DOIs | |
| State | Published - 15 Aug 2009 |
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Accounting for surface roughness effects in the near-infrared reflectance sensing of soils. / Wu, Chun-Yu; Jacobson, Astrid R.; Laba, Magdeline; Baveye, Philippe C.
In: Geoderma, Vol. 152, No. 1-2, 15.08.2009, p. 171-180.Research output: Contribution to journal › Article
TY - JOUR
T1 - Accounting for surface roughness effects in the near-infrared reflectance sensing of soils
AU - Wu,Chun-Yu
AU - Jacobson,Astrid R.
AU - Laba,Magdeline
AU - Baveye,Philippe C.
PY - 2009/8/15
Y1 - 2009/8/15
N2 - Near-infrared reflectance sensing (NIRS) has stimulated widespread enthusiasm in recent years among soil scientists, in part for its potential to lead to the design of new “proximal” soil sensors in support of precision agriculture, and to increase significantly the amount of information that can be obtained about soils from remote sensors. However, a practical difficulty this technique faces is that soils in the field, unlike the sieved, repacked soil samples used in the laboratory, are generally moist and have uneven surfaces, especially after tillage. Unfortunately, little is known at this point on the effect of surface roughness on NIR spectra. In this context, the present research focuses on the application of NIRS, under laboratory conditions, to chunks (artificially isolated particles or aggregates) of soil of average sizes between 0.04 and 8 mm, obtained in 5 different soils with contrasting features, and repacked in Petri dishes. NIRS measurements were performed when the soils were air-dry, and after rewetting to near-saturation. In virtually all cases, except at the finest chunk size in two soils, the near-infrared reflectance decreased regularly as chunk size increased. Nearsaturation of the soils with deionized water resulted in further decreases in reflectance, which obliterated to varying extent the dependence of the reflectance on chunk size. For most cases, whether the soils were dry or near-saturated, computation of the first derivative of the NIR spectra, especially when preceded by movingaverage or wavelet-based smoothing, resulted in transformed signals that were virtually independent of surface roughness in a number of distinct spectral regions. These observations suggest that in the range of soil chunk sizes considered, it might be possible practically to circumvent the dependence of NIRS on surface roughness.
AB - Near-infrared reflectance sensing (NIRS) has stimulated widespread enthusiasm in recent years among soil scientists, in part for its potential to lead to the design of new “proximal” soil sensors in support of precision agriculture, and to increase significantly the amount of information that can be obtained about soils from remote sensors. However, a practical difficulty this technique faces is that soils in the field, unlike the sieved, repacked soil samples used in the laboratory, are generally moist and have uneven surfaces, especially after tillage. Unfortunately, little is known at this point on the effect of surface roughness on NIR spectra. In this context, the present research focuses on the application of NIRS, under laboratory conditions, to chunks (artificially isolated particles or aggregates) of soil of average sizes between 0.04 and 8 mm, obtained in 5 different soils with contrasting features, and repacked in Petri dishes. NIRS measurements were performed when the soils were air-dry, and after rewetting to near-saturation. In virtually all cases, except at the finest chunk size in two soils, the near-infrared reflectance decreased regularly as chunk size increased. Nearsaturation of the soils with deionized water resulted in further decreases in reflectance, which obliterated to varying extent the dependence of the reflectance on chunk size. For most cases, whether the soils were dry or near-saturated, computation of the first derivative of the NIR spectra, especially when preceded by movingaverage or wavelet-based smoothing, resulted in transformed signals that were virtually independent of surface roughness in a number of distinct spectral regions. These observations suggest that in the range of soil chunk sizes considered, it might be possible practically to circumvent the dependence of NIRS on surface roughness.
U2 - 10.1016/j.geoderma.2009.06.002
DO - 10.1016/j.geoderma.2009.06.002
M3 - Article
VL - 152
SP - 171
EP - 180
JO - Geoderma
T2 - Geoderma
JF - Geoderma
SN - 0016-7061
IS - 1-2
ER -