Basic Cation Saturation Ratio

A theoretical recommendation following soil testing for maintaining a defined balance between different cations of calcium (Ca2+), magnesium (Mg2+) and potassium (K+) in a ratio (although this varies depending on author and crop) of 70:10:5, with the remainder primarily being hydrogen (H+) ions within a soil. The aim being to ensure maximum crop yield by ensuring the supposed optimum ratio is maintained.

Where an imbalance is found, the recommendation is to apply certain nutrients to bring the ratio back into an appropriate balance. The practical application of this ratio is not generally recommended for turf situations due to the wide range of biological, chemical, and physical conditions found within soils which find the ratio has little influence on such conditions and that maximum yields are not a requirement of turfgrasses. Whilst the concept can appear persuasive, the validity of it has been questioned on numerous occasions and “[t]he data do not support the claims of the BCSR, and continued promotion of the BCSR will result in the inefficient use of resources in agriculture and horticulture.” (Peter M. Kopittke, Neal W. Menzies (2007), ‘A Review of the Use of the Basic Cation Saturation Ratio and the “Ideal” Soil’, Soil Science Society of America Journal, Vol.71, Issue 2, pp259-265, https://doi.org/10.2136/sssaj2006.0186)
(See also:
1. Adams, F. (Ed), (1984) ‘Soil acidity and liming’, (2nd Edn), Monograph No. 12, American Society of Agronomy, pp292-294)
2. McCarty, L.B. (2018), ‘Golf turf management’, CRC Press, pp271-274)