Abstract

GARCIA-RUIZ, Rafael; SANCHEZ-HERNANDEZ, Rufo; BAUTISTA, Francisco  and  GOGUITCHAICHVILI, Avto. Colorimetric method to estimate the soil organic matter in karst areas. Ecosistemas y recur. agropecuarios [online]. 2022, vol.9, n.1, e3189.  Epub Dec 09, 2022. ISSN 2007-901X.  https://doi.org/10.19136/era.a9n1.3189.

The increase in soil organic matter (SOM) content contributes to the mitigation of the effects of global climate change; thus, it is important to know its levels. However, the SOM analysis can eventually be expensive and time consuming, as well as generating toxic waste. The measurement of soil color may be an indirect method more practical to estimate the SOM than traditional techniques. The principal aim of the study was to use color parameters through the CIE Lab system and some color indices, such as saturation and redness indices, to estimate the SOM in a karst area of the municipality of Chetumal in the Yucatan Peninsula, Mexico. The percentage of SOM was measured in 50 soil samples by conventional methods while the soil color was analyzed with the CIE Lab system. Both variables were correlated with the redness index. Based on color, the samples were separated into five groups, ranging from pinkish white to brownish gray. Multiple regression equations (SOM vs soil color parameters) were performed for each group and a medians comparison analysis was applied. The correlation adjustment between the redness index and SOM is R2> 0.86. The values of the multiple regression equations were R2> 0.8. We conclude that the soil redness index, now named soil organic matter index, can be used as a relatively quick approach to estimate the percentage of SOM in karst areas.

Keywords : Organic matter; redness index; soil color; proxy method; karst..