The sampling scheme was explained as recommended (M&M, subheading 2.1). In general, sampling scale changes between 1:12 000 and 1:250 000 (Soil Survey Staff, USDA NRCS 2016). In this pioneering study area, soil properties are highly variable attributed to topography, land use history and land tenure ownerships (mainly 0.2-0.3 hectares and fragmented shrubbery areas) and geological setting that makes difficult to apply regular sampling scheme. Therefore, the sampling locations were randomly (irregularly) designated, yet cover variations in land use, topography, geological substrate and the erosive state of soil continuum thereby resulted in 114 samples from 525 ha used under four land use types (1 sample per ~ 5 hectares).
It is also not clear how 50 spectra were obtained.