The soil data layers from soilgrid.org provides access to grid layers representing the spatial distribution of soil properties across the globe. There are various ways to access this data, including the Web Coverage Service (WCS) protocol. This post provides an example of how to use the OWSLib pacakge to access soil grid layers for your area of interest.
The graphical modeler is a great way to automate tasks, using the routines in the QGIS toolbox. However, what to do if you need a function not available in the toolbox? In that case you may want to look into writing your own script.
Programs like R and GRASS GIS are incredible powerfull. But occasionally you'll need a functionality that is not available yet. Luckily, depending on the kind of functionality, it isn't terribly difficult to create your own scripts. In the past years I have created a few scripts that I hope are useful to others as well.