The Albrecht system: explanation and reasons why not to use it
- The Albrecht system uses the Base Cation Saturation Ratio (BCSR) to compare ratios of cations in soil solution, and from this, ‘ideal’ values are recommended.
- The system is based on a very limited amount of work undertaken in the 1940s in USA. The purpose of the original work by Bear et al. was to limit luxury K uptake, by using Ca2+ to out-compete K+ but the idea was promoted and expanded by Albrecht in the following years and is still used by some companies to recommend fertiliser applications.
Why not to use it
- The original work was fundamentally flawed: although there was a difference in yield between cation ratios, the ratios were effected by applying treatments which also changed the soil pH; this affect was not accounted for.
- The Albrecht system takes no account of the absolute amount of any given nutrient that is present, and only recommends relative ratios (as a proportion of the CEC). Therefore in theory, very low concentrations of everything would be considered satisfactory, as long as the ratios were ‘correct’, even if there was clearly insufficient of any one nutrient present to support crop growth.
- A search of relevant scientific literature published between 1945 and 2018 provided no examples whatsoever which supported this theory, however there are numerous examples which show it does not hold.
- The following table and graph are examples of data showing that the Albrecht system is flawed.
Table 1. Examples cited by Kopittke & Menzies (2007) showing that the ratio of Ca:Mg did not affect crop yields (from Calcium and magnesium 2018).
Figure 1. Data from McLean et al (1983) in Rehm (1994). Corn and soybean grown in 4 different years, under 18 different soil treatments. Ratios of Ca:Mg were calculated for the 5 most productive and 5 least productive treatments, and the ranges are shown here as yellow and green bars respectively. Red lines show ‘ideal’ ratios as calculated by BCSR. From Potassium application to potatoes 2014.
Notes on problems with the Albrecht system
Calcium and magnesium 2018 (The Albrecht system does not indicate nutrient requirements)
Potassium application to potatoes 2014 (Nutrient ratios do not indicate amounts available)