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| Volume 105(2) 2005, pages: 1-14. | | Niels Henrik Broge, Mogens Humlekrog Greve & Rene Larsen: | Estimating topsoil organic matter content in two experimental fields in Denmark using multi-spectral aerial imagery and topographic data | | The potential use of spectral reflectance data and topographical
measurements for the estimation of topsoil organic matter (SOM)
content is investigated. Intensive measurements of soil texture and
topography in two Danish fields combined with digital aerial photographs,
representing blue, green, red and nearinfrared wavelength
regions, form the basis of the investigation. Analyses of semivariograms
indicate similarity between the spatial variation of the
spectral, topographic and textural measurements, and confirms
that the sampling density is sufficient to account for the spatial variation
of SOM within each field. Multivariate statistics were applied
to investigate the potential of spectral reflectance data, including
selected spectral indices, and topographical data for prediction of
SOM. The results show that the spectral reflectance data obtained
within the visible and near infrared range are correlated with the
SOM content in both fields, and that the spectral bands are almost
co-linear. The relative importance of spectral reflectance and topographical
data varied in the two fields, although the combined use
of these data improved the estimation of SOM significantly in both
fields. The data indicated that SOM content above 3.5% was rare in
both fields although a high SOM content was found in one field,
which was related to kettle holes characterised by poor drainage.
The study focused on the estimation of SOM from zero to 3.5%
within the 2 fields. The Predicted accuracy varied between 0.24 and
0.30 % SOM, depending on the field and input parameters used in
the model. The results also revealed that the data used in the investigation
were insufficient to properly describe the variations of
SOM within the fields. | | >> download as pdf |
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