It is difficult to determine the validity of the wide range of methods and interpretations, claimed to be based on the Albrecht system, that are provided by commercial laboratories while they remain unpublished. Albrecht worked with US soils and a limited range of crops, and agronomic advice can only be effective if backed up by field trials under conditions prevailing in one's own country. Loveland admits that one area where the BCSR method is undoubtedly right is in its advocacy of the use of organic matter in crop rotations, even if the benefits are hard to quantify (P.J. Loveland, Cranfield University, Silsoe, 2000, personal communication. See http://www.silsoe. cranfield.ac.uk). For views favouring the Albrecht-BCSR system and details of analytical services in the USA based on this method, see the soil management page of the Appropriate Technology Transfer for Rural Areas website at:
The BCSR theory originated in New Jersey with Bear and co-workers (e.g. Bear and Prince, 1945; Bear and Toth, 1948). Following work with lucerne (Medicago sativa L.), they proposed an 'ideal ratio' of cation saturation of 65% Ca, 10% Mg, 5% K and 20% H. One of Albrecht's colleagues at the Missouri Agricultural Experiment Station was Dr E.R. Graham, who published an explanation of the BCSR theory and methods of soil testing (Graham, 1959). This theory was examined by researchers at the Department of Agronomy, Ohio State University, Columbus, and at the Ohio Agricultural Research and Development Centre, Wooster. Trials carried out, with the results appearing in three papers by McLean (1977), Eckert and McLean (1981) and McLean et al. (1983), and a chapter by Eckert (1987). They compared the BCSR approach with the sufficiency level of available nutrient (SLAN) viewpoint, which is credited to Bray (1944, 1945). The 1981 paper found that lucerne grew well at several ratios, and the data indicated that the balance of cations in the soil was unimportant, except at the extremely wide ratios where deficiencies of one element were caused by excesses of others. Hence no best ratio existed for Italian millet (Setaria italica (L.) Beauv.) or lucerne. The 1983 paper concluded that 'The results strongly suggest that for maximum crop yields, emphasis should be placed on providing sufficient, but non-excessive levels of each basic cation, rather than attempting to attain a favourable BCSR which evidently does not exist.' Weighing the two viewpoints, one can say that although BCSR values provide guidelines and broad limits of variation, recommendations must ultimately follow trials to determine the response of the crop in question under the expected field conditions, and one cannot be dogmatic about specific ratios. By 1987, Eckert concedes that both concepts can provide reasonable fertilizer recommendations if interpreted properly, however, the BCSR recommendations, unlike the SLAN, are not justified by agronomic research.
The Potash Development Association (PDA, 2000) reports that assessors in the US regarded the BCSR concept as most applicable to highly weathered soils of low pH requiring relatively major adjustments in fertility and where high Mg levels need to be maintained. As there are few such soils in the UK, it is questionable as to how applicable this concept is to the majority of UK soils.
For comments on BCSR versus SLAN for turfgrass, see the 1999 Iowa Turfgrass Research Report at the website:
http://www.hort.iastate.edu/pages/news/turfrpt/1999/calciumrod.html Cation saturation ratios are also discussed in an article on the philosophy of soil testing in the National Corn Handbook, found at the website:
http://www.agcom.purdue.edu/AgCom/Pubs/NCH/NCH-2.html The ineffectiveness of trying to achieve specific cation saturation ratios is presented in an article by Dr George Rehm (University of Minnesota) in the Wisconsin Crop Manager at:
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