Abstract <p>Five field surveys of the same territory (Bazarno-Karabulaksky district of the Saratov region) were conducted to establish functional relationships between the soil organic matter (SOM) content and the multitemporal spectral characteristic of the open soil surface (OSS). The surveys differed in the methods of planning sampling sites. Three methods implied traditional approaches using regular and irregular grids, and two methods used a map of the coefficient <i>C</i> of multitemporal (empirical) soil line. It is shown that the traditional methods make it difficult to obtain a stable relationship between the values of the spectral characteristics of remote sensing data and the SOM content. The determination coefficients of such dependencies are &lt;0.60, which does not allow us to recommend the obtained dependencies for the purposes of SOM mapping. Organization of field work based on a preconstructed map of the coefficient <i>C</i> of multitemporal soil line makes it possible to establishing functional relationships between the SOM content and the multitemporal spectral characteristics of the OSS with a determination coefficient of 0.81. The reason for the different quality of the regression models is the omission of a number of soil objects during traditional organization of field work and problems in positioning the sampling points. Correction of traditional field surveys using multitemporal spectral characteristics of the OSS allows us to improve the quality of research and develop new methods for SOM mapping.</p>