Digitization and mapping of national legacy soil data of Montenegro

This paper describes the process of digitizing Montenegro's legacy soil data, and an initial attempt to use it for digital soil mapping (DSM) purposes. The handwritten legacy numerical records of physical and chemical properties for more than 10 000 soil profiles and semi-profiles covering whole Montenegro have been digitized, and, out of those, more than 3000 have been georeferenced. Problems and challenges of digitization addressed in the paper are: processing of non-uniform handwritten numerical records, parsing a complex textual representation of those records, georeferencing the records using digitized (scanned) legacy soil maps, creating a single computer database containing all digitized records, transforming, cleaning and validating the data. For an initial assessment of the suitability of these data for mapping purposes, inverse distance weighting (IDW), ordinary kriging (OK), multiple linear regression (LR), and regression-kriging (RK) interpolation models were applied to create thematic maps of soil phosphorus. The area chosen for mapping is a 400 km2 area near the city of Cetinje, containing 125 data points. LR and RK models were developed using publicly available digital elevation model (DEM) data and satellite global land survey (GLS) data as predictor variables. The digitized phosphorus quantities were normalized and scaled. The predictor variables were scaled, and principal component analysis was performed. For the best performing RK model an R2 value of 0.23 was obtained.