Rewriting PTR salinity, alkalinity, chemical toxicity and drainage based on the wrb-standard
Description of the current PTR used to derive alkalinity
The current rule used for estimating alkalinity in CGMS is described in Table 4-8.
In the current rule, alkalinity is estimated as strong only if the soil is a Solonetz (FAO-UNESCO 1974 legend).
Alkalinity of soil has two effects on crops. The first one is a toxicity effect due to the Sodium ions. The second effect is an indirect one due to a massive or columnar structure and a lower permeability of the soil which are unfavourable conditions for rooting and ploughing. It is measured by the ratio between the exchangeable sodium and the exchange capacity, called ESP.