Z. Y. Zhao, M. I. Ashraf, and F. Meng, Model prediction of soil drainage classes over a large area using a limited number of field samples: A case study in the province of Nova Scotia, Canada. Canadian Journal of Soil Science, vol.93, issue.1, pp.73-83, 2013.

Z. Y. Zhao, T. L. Chow, Q. Yang, H. W. Rees, G. Benoy et al., Model prediction of soil drainage classes based on digital elevation model parameters and soil attributes from coarse resolution soil maps, Canadian Journal of Soil Science, vol.88, issue.5, pp.787-799, 2008.

, Classification and mapping of soil pH depth function groups for Denmark Kabindra Adhikari 1, José Padarian 2 and Mogens H. Greve, vol.2

O. Drive and . Madison, This study modeled the depth functions of 1934 soil profile pH measurements (1:2.5 soil-water ratio) and mapped its spatial distribution for entire Denmark at 30-m grid spacing. The pH depth function was modeled with equal-area spline function, and predictions at unsampled location were made by rule-based regression kriging that employed soil, terrain, land use, and climate data as factors of pH variations. Model validation on 25% unused data showed a R 2 range of 0.51 (100-200 cm) to 0.57 (15-30 cm), and RMSE of 0.82 to 0.56 for the same depth intervals. Geology, soil types, land use, precipitation and slope were among the key variables affecting soil pH distribution, Blichers Allé, vol.20

, Range of pH values for those classes were-pH >7 throughout; 5.5 < pH <7 throughout; pH <=5.5 throughout; 5.5 < pH <7 on 0-30, and increase with depth; pH <=5.5 on top and increase with depth; 5.5 < pH <7 on 0-30 and decrease until 60-100, but increase in 100-200; and 5.5 < pH <7 on 0-30 and decrease with depth, Comparison of these results with the Global SoilGrids revealed that the latter always had lower pH with a narrow range throughout the profile