Calculating K factor for soil erosion using ISRIC database

[Antoine Guy]

Hello everyone, 

I am working on soil erosion and I am trying to compute K factor worldwide using ISRIC database as it is used in many paper for RUSLE based equation model.

However , I can't find factors used in this equation in the ISRIC database (or I don't understand it correctly).

The equation : 

K-factor formula: К = 2.77 10-7 M 1.14 (12 – a) + 0.0043 (b – 2) + 0.0033 (4 – c) 

where: M = {%(silt + fine sand)} . {100 - %clay}, a is %OM, b is the soil structure class and c is the soil profile permeability class)

 What I miss is b : the soil structure and c : the permeablity class.

Do you know how can I find / figure out this factors ? 

Best regards , 

Antoine