摘要：
[Objective]Soil color is a reflectance spectra characteristic of the soil in the visible light band and also a kind of visual perception. The Munsell color chart is a traditional tool to determine Munsell color of soils, however, soil color determination by color charts may be subjective due to the impacts of human subjective consciousness and environmental conditions. With advancement of the optical technology, numerous instruments have been developed one by one for determining soil colors, such as spectrographs, digital cameras, and even more convenient mobile phones that can all be used to determine soil colors.However, spectrometers are often quite expensive and bulky, and digital cameras and mobile phones are not so easy to get calibrated. So portable colorimeters pop up as a new type of tool that has the advantages of being small in size, easy to carry, and moderate in price. The use of colorimeters to determine soil colors helps to avoid subjective factors and some objective environmental factors, and hence improves work efficiency. The object of this study is to compare the New Standard Soil Colour Charts with two types of portable colorimeters in determining Munsell color of soils, in an attempt to find out differences between them and select a superior one for determination of Munsell color of soils.[Method]A total of 97 soil samples of 27 soil series were collected in the Central Sichuan hilly region, for determination of Munsell color after they were purged of plant and animal residues, air-dried, ground to pass a sieve, and mixed to get homogenized, separately. Each sample under went three treatments, that is, determination of Munsell soil color, with the New Standard Soil Colour Charts, Nix and CM600 d, separately. The data of hue, value and chroma of soil Munsell color could be achieved directly via ocular estimation of the sample against the New Standard Soil Colour Charts, the use of CM600 d, and the use of the color conversion formula to process the CIE XYZ data obtained with NIX. Then with the help of statistical parameters and rules for grading differences in Munsell soil color, comparison was done of the data obtained with the three different methods.[Result]The hue of the air-dried soil in Central Sichuan hilly area lingered mainly in YR, with5 YR and 10 YR appearing the most frequently, or 33 and 30 times, respectively. The soil classified as purple soil in the Chinese Soil Genetic Classification System, after being air-dried, did not show any hue of RP, and lingered in the range of 4～8 in value and in the range of 2～6 in chroma, with "value/chroma" ratio being 5/3, 5/4, 6/4 and 7/4, the most frequently, indicating that the soils tested were quite high in value, but low in chroma. With the result of the ocular estimation method as reference for comparison, the Munsell soil color obtained with the colorimeter method tended to be yellowish and agreeable value and chroma. The RMSE of hue, value and chroma measured with the CM600 d was 1.74, 0.98 and 0.97 unit, respectively, and that with the NIX was 2.04, 0.57 and 0.88 unit, respectively. The difference between the ocular estimation method and the colorimeter methods in Munsell soil color could be graded into"Faint", "Distinct"and"Prominent", which was 90.72％, 8.25％ and 1.03％, respectively, for CM600 d and 84.54％, 14.43％ and1.03％, respectively for NIX.[Conclusion] The two kinds of colorimeters are useful to help researchers measure Munsell soil color, and improve accuracy of the measurement, too. The Nix method is closer to the ocular estimation method in measuring value of the Munsell soil color and moreover superior in price.%Munsell色卡是测定土壤颜色的传统工具, 而测色仪是测定土壤颜色的新兴仪器.利用统计参数及相关颜色差异等级, 比较2种原理、价格不同的测色仪测定川中丘陵区27个拟定土系共97个过2 mm筛风干土壤Munsell颜色与利用《中国标准土壤色卡》目测 (即目测法) 的差异.结果表明, 川中丘陵区风干土壤色调集中于YR色调, 未出现RP色调, 明度较高, 彩度较低.2种测色仪均较目测法测定土壤Munsell颜色色调偏黄, 但明度、彩度较一致;以目测值为参照, CM600d实测值和Nix校正值的色调、明度、彩度均方根误差 (RMSE) 分别为1.74、0.98、0.97和2.04、0.57、0.88, 与目测差异等级为"微弱"、"明显"和"强烈"数量分别为90.72％、8.25％、1.03％和84.54％、14.43％、1.03％, 表明使用2种测色仪均能辅助研究者判别土壤颜色, 提高土壤颜色判别精确度, Nix测定土壤Munsell颜色明度更接近目测, 且更具价格优势.
