However, many proponents of 'ideal soil' theories also stress the importance of balancing the anions phosphorus, sulphur and chlorine as well as numerous minor and trace elements.
There is currently no publicly available research or trial data to support these claims,[3] but BCSR systems are fairly widely used in organic farms and many positive testimonials from farmers and gardeners can be found on the internet and in alternative agriculture literature.
Later, in 1933, Moser also reviewed the literature and performed his own experiments, coming to the same conclusion as Lipman that there was no evidence for the Ca:Mg ratio influencing yield.
[6] At his death he left his papers to his friend Charles Walters who promoted the ideas by founding the magazine AcresUSA, which continues to be at the centre of the ideal soil movement.
Bear in New Jersey was investigating whether calcium amendments could be used to limit the excess uptake of potassium in alfalfa plants in order to reduce fertiliser costs.
From these studies he issued a bulletin with Prince and Malcolm in 1945 that tentatively proposed an 'ideal soil' ratio where the proportions of exchangeable cations were 65% Ca, 10% Mg, 5% K and 20% H.[12] They confirmed their hypothesis with further experiments in 1948 (published with Toth).
Perhaps the most controversial aspect of BCSR (and organic farming in general) relates to the practitioners' beliefs that a correctly balanced soil will yield more nutritious produce.
[27] It has been speculated that hybrid varieties bred for yield, uniformity, pest resistance, appearance, and shelf life over taste (a good indicator of nutritional quality) may be at fault rather than the soil.
William Albrecht first theorised that crops grown on 'unbalanced' soils are of lower nutritional value, based on studying the habits of grazing cattle – noting in particular their avoidance of the lush grass that grew on dung patches.
Another study worth mentioning for its prevalence in the alternative agriculture literature is that undertaken by Bear and Toth in 1948 investigating the mineral composition of fruit and vegetables on a range of different soils across the US.
The study suggests that soil composition effects mineral content of crops, but due to the large numbers of unexplored variables it is difficult to draw firm conclusions.
Schonbeck's farm trials [30] found that a reduction in Mg saturation had no effect on compaction, moisture content, infiltration rate, or soil strength.
Studies have backed this up—Schonbeck[30] showed that a reduction of Mg saturation had no detectable effect on soil organic matter, biological activity, weed growth, or incidence of disease.
There are claimed to be over a million acres (4,000 km2) of farmland worldwide using some kind of BCSR theory for balancing their soils, and the testimonies of farmers seem to back it up as a practical method.
For example, integrated pest management requires the use of polycultures, cover crops, reduction of pesticides and even agroforestry to a degree, and its efficacy will be greatly reduced if all these things are ignored.
[41] Aside from these worries, the general consensus is that the only negative effects for farmers using BCSR will be the unnecessary expense which could have been better spent on other sustainable agricultural practices whose benefits are well studied.
[42] While fertiliser recommendations based on BCSR continue to be in widespread use by private soil testing laboratories, the evidence on balance suggests there is no benefit to crop yield or quality.
Any perceived change is likely to be due to correction of deficiencies (which would have been picked up by the SLAN method) or the result of other beneficial soil practices used in conjunction, when transitioning to sustainable agriculture.