A scientist of the Soil Science Department of the Lomonosov Moscow State University together with the colleagues have designed a simple technique for quantitative characteristic of soil colour with the help of a low-cost digital device. The available colour control technique is promising as it decreases incorrect diagnostic of soil horizons and consequently, increases the accuracy of soil maps.
Natalia Kirillova, Doctor of Biology, Junior Researcher at the Laboratory of Soil Genesis and Classification, the Faculty of Soil Science of the Lomonosov Moscow State University and the first article author shares: «With the help of proper calibration a usual office flatbed scanner could be transformed into a tool for measuring soil colour at the spectrophotometer level. The scientific value lies in the fact that we have found a method for a simple quantitative colorimetric analysis of soil horizons. "
Spectrophotometers are devices to measure the reflectance spectrum of soils (namely, wavelength distribution of spectral reflection coefficients). The reflection spectrum and its derivatives determine the colour specificity of soil horizons.
The scientists collected and analyzed a large number of soil samples. They have used reflectance spectrophotometry along with methods of image analysis and mathematical transformations from one colour spaces to another.
The scientists say that an advantage of using an office scanner lies in the transition from descriptive (verbal) characteristics of soil colour to the quantitative ones. The Munsell colour charts have been the primary qualitative or semi-quantitative means to describe soil colour. We propose to use The Munsell colour charts not for direct colour determination, but only for calibration of the scanner. In combination with the scanner, this method of measuring colour is close in accuracy to the level of the spectrophotometer.
Natalia Kirillova comments: "Soil scientists all over the world focus on soil organic carbon (??) evaluation. Modern estimates show that soil is the main depot for conservation of organic carbon on land. For global assessments soil maps are used, where distribution of horizons with different content of ?? is indicated. During field diagnosis (especially in case of wet soils) horizons with OC difference of several times could be easily confused. This will lead to huge errors in mapping, and therefore, in estimating the amount of organic carbon in the soil. The proposed new method of colour control allows to significantly reduce the risk of such mistakes."
Scientists from the V.V. Dokuchaev Soil Science Institute, RAS and University of Aberdeen, UK have taken part in the project.