ABSTRACT Soil color has been conventionally measured using a Munsell soil color chart. Recently launched colorimeters can also measure the color of an object at a reasonable cost. This study was undertaken to evaluate to what extent such low-cost colorimeters (< 500 USD) can be useful for soil color analysis in the laboratory as compared with conventional colorimeters (> 3000 USD) and a Munsell soil color chart (about 200 USD). Sixty two air-dried soil samples collected from rice fields in Madagascar were subjected to two pretreatments for homogenization (2-mm sieving or additional hand-grinding) and instrumental analysis using four low-cost colorimeters (CS-10, Cube, Nix Pro, and Color Muse) and four conventional colorimeters (SPAD-503, CR-20, CR-400, and CR-410). The color of 2-mm sieved samples was also measured visually using a color chart. The effects of pretreatments and the analytical conditions were evaluated by the repeatability and stability of the measurement, the comparability of the soil color data obtained, and the time required for analysis. Overall, instrumental measurement was much more repeatable than visual observation. Both the repeatability and stability of the low-cost colorimeters tended to be lower than those of the conventional colorimeters. Among the low-cost colorimeters examined, soil color parameters (L*, a*, and b*) obtained with Nix Pro were most comparable (r > 0.97 for all parameters of 2-mm sieved samples) with those obtained with SPAD-503, which is an instrument designed specifically for soil color analysis. Additional hand-grinding pretreatment improved the repeatability of the instrumental analysis and reduced the subsample weight to two grams. However, this pretreatment also increased the L* value (lightness) of the samples, decreased the comparability with the data from 2-mm sieved samples, and prolonged the time required to complete the whole analysis. Among the various methods tested, 2-mm sieving of air-dried samples followed by the color measurement with Nix Pro several times per sample was considered the most cost-effective approach for measuring soil color in the laboratory.

中文翻译：

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不同低成本色度计对土壤颜色的视觉和仪器测量的比较

摘要 土壤颜色通常使用孟塞尔土壤颜色图表进行测量。最近推出的色度计还可以以合理的成本测量物体的颜色。本研究旨在评估与传统色度计（> 3000 美元）和孟塞尔土壤色度图（约 200 美元）相比，这种低成本色度计（< 500 美元）在实验室中对土壤颜色分析的有用程度. 从马达加斯加稻田收集的 62 份风干土壤样品进行了两次均质化预处理（2 毫米筛分或额外的手工研磨）和使用四个低成本色度计（CS-10、Cube、Nix Pro、和 Color Muse）和四个传统色度计（SPAD-503、CR-20、CR-400 和 CR-410）。2-mm 筛分样品的颜色也使用颜色图表目测测量。通过测量的重复性和稳定性、获得的土壤颜色数据的可比性以及分析所需的时间来评估预处理和分析条件的影响。总体而言，仪器测量比目视观察更具可重复性。低成本色度计的重复性和稳定性往往低于传统色度计。在检查的低成本色度计中，使用 Nix Pro 获得的土壤颜色参数（L*、a* 和 b*）与使用 SPAD-503 获得的参数最具有可比性（对于 2 毫米筛分样品的所有参数，r > 0.97） ，这是一种专为土壤颜色分析而设计的仪器。额外的手工研磨预处理提高了仪器分析的可重复性，并将子样品重量减少到 2 克。然而，这种预处理也增加了样品的 L* 值（亮度），降低了与 2 毫米筛分样品数据的可比性，并延长了完成整个分析所需的时间。在测试的各种方法中，对风干样品进行 2 毫米筛分，然后使用 Nix Pro 对每个样品进行多次颜色测量，被认为是实验室中测量土壤颜色最具成本效益的方法。并延长了完成整个分析所需的时间。在测试的各种方法中，对风干样品进行 2 毫米筛分，然后使用 Nix Pro 对每个样品进行多次颜色测量，被认为是实验室中测量土壤颜色最具成本效益的方法。并延长了完成整个分析所需的时间。在测试的各种方法中，对风干样品进行 2 毫米筛分，然后使用 Nix Pro 对每个样品进行多次颜色测量，被认为是实验室中测量土壤颜色的最具成本效益的方法。