Application of a Novel Digital Image Colorimetry Method for Assessment of Soil Salinity

Muir, M. R. and Innes, A. (2023) Application of a Novel Digital Image Colorimetry Method for Assessment of Soil Salinity. SETAC Europe 33rd Annual Meeting, Dublin, Ireland, 30 April-04 May 2023.

Abstract

Salinization is one of the largest threats facing soils globally as a result of rising sea levels and the use of saline groundwater for crop irrigation. Saline soils have been identified in over 100 countries worldwide, affecting over 1 billion hectares of land. Understanding the scale and extent of soil salinity is essential to enable farmers and land managers to make appropriate decisions about how to effectively apply practices which can help to reduce the impact of problems associated with saline soils. However, soil salinity analysis methods are frequently prohibitively expensive or time consuming, therefore access to low-cost, simple, fast and robust measurement techniques is desirable to help inform land-management approaches and to provide accessible analysis techniques to all practitioners, without cost being a barrier. In this project, a novel smartphone-based Digital Image Colorimetry (DIC) technique using colorimetric chloride test strips has been developed and compared to other portable and lab-based techniques for the assessment of soil salinity. A survey of a coastal saltmarsh and neighbouring farmland was conducted at the RSPB Mersehead Nature Reserve in Southwest Scotland. The salinity of 70 soil samples was analysed by the new DIC method, as well as 3 other portable and 2 lab-based methods. Comparisons were drawn between the methods in terms of practicality and ease of use, cost effectiveness, accuracy, and precision of measurement. Results presented show that the new DIC method compares very favourably with standard analytical methods for soil salinity, with a correlation coefficient of 0.98 (p<0.001) and 0.96 (p<0.001) with chloride meter and conductivity methods, respectively. The DIC method also performed better than a portable soil conductivity sensor. An application of the DIC method, and other methods evaluated, is demonstrated by using geostatistical analysis (Kriging) to estimate soil salinity across the ~7km2 Mersehead site, highlighting significant variation in salinity across the area. Each technique evaluated had specific benefits, such as accuracy, precision, selectivity or speed, however the low cost, portability and lack of specialist equipment required for the DIC technique makes it suitable for use in agriculture, citizen science or conservation settings where resources may be limited. The example presented demonstrates how smartphones may be used successfully to broaden access to environmental analysis techniques.

• Item Type: Conference or Workshop Item
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Muir, Dr Michael
• Authors: Muir, M. R., and Innes, A.
• Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences; Q Science > QD Chemistry; S Agriculture > S Agriculture (General); T Technology > T Technology (General)
• College/School: College of Social Sciences > School of Social & Environmental Sustainability
• Research Group: Environmental Sience and Sustainability

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