Rewriting PTR salinity, alkalinity, chemical toxicity and drainage based on the wrb-standard
Description of the current PTR used to derive drainage
The current rule used for estimating drainage in CGMS is described in (Table 4-20). It was first described by van Dam et al. (1994) and later updated by van Diepen (1997).
The drainage classes are derived on the basis of the FAO soil name, agricultural limiting phases and topsoil texture. The procedure is executed in the same order as the rows appear in this table. So, first the STUs with phase 21 are selected and labelled class 'W' and in the following step all remaining STUs are compared with the next rule and so on. The '*' indicates that on the considered position any character could be read.
The drainage classes are referring to the definition of drainage classes as given by FAO in the guide for soil description (FAO, 1994). These classes take into account the frequency and the duration of the periods in the year where the soil is not saturated by water.
Table 4-20: The pedotransfer rules to derive the drainage class in CGMS
The drainage classes are referring to the definition of drainage classes as given by FAO in the guide for soil description (FAO, 1994). These classes take into account the frequency and the duration of the periods in the year where the soil is not saturated by water.
