Base saturation is an inadequate term for Soil Science

Abstract

Bases are chemical species that donate electrons, accept protons, or release hydroxyls (OH -) in aqueous solution. In Soil Science, "base saturation", "exchangeable bases" or "basic cations" has been widely used to distinguish Ca 2+ , Mg 2+ , Na + , and K + from H + and Al 3+ cations. This terminology is confusing since none of these cations are truly a base in chemistry sense. However, in the absence of the proposition of a correct term, the term "base saturation" remains in use nowadays, causing confusion among students, professionals, and even among professors and researchers in Soil Science, as it leads to the erroneous interpretation that the soil acidity can be corrected by adding these cations to the soil. Here, we present the historical background of this nomenclature and a theoretical foundation that justifies the abolition of the use of these terms in Soil Science. We consider that the most correct is to call it "Ca-Mg-K-Na saturation", which, despite being long, would refer directly and without any misinterpretation of the terminology. In Soil Fertility, the "base saturation" is often calculated only as a function of the sum of Ca, Mg, and K, since the Na content is negligible in most tropical and subtropical soils. Thus, one could use the term "Ca-Mg-K saturation". Likewise, it is also suggested to abolish the use of the term "sum of bases" and use the term "sum of Ca-Mg-K" or "sum of Ca-Mg-K-Na" instead when necessary.

Sustainable Rehabilitation of Post-Bauxite Mining Land for Albizia falcata Cultivation Using Specific Location Amelioration Technology

“…This can be attributed to the presence of basic cations such as K, Ca, Mg, and Na in red mud, which contributes to its high BS value of 96.83%, compared to the untreated Ultisol soil BS of approximately 3.7%. Base saturation (BS) is a measure of the percentage of total cation exchange capacity occupied by basic cations such as K, Ca, Mg, and Na [67,68]. The results suggest that red mud and cow manure fertilizers can be used as effective soil amendments to improve soil fertility and productivity by increasing the soil's BS value (Figure 10).…”

Response to Letter to the Editor on “Base saturation is an inadequate term for Soil Science”

“…In response to the Letter to the Editor on "Base saturation is an inadequate term for Soil" (Tiecher et al, 2022), the editors of RBCS, Reinaldo Bertola Cantaritti and José Miguel Reichert, would like to thank for the issues raised and discussion provided by the authors on the terms "sum of bases" and "base saturation" .…”