Basic cation saturation ratio

From the early 1930s, his research often involved the study of the colloidal clay fraction, its cation exchange properties, and the optimum percentages (or ratios) of basic cations for balanced plant nutrition. This is now called the basic cation saturation ratio (BCSR) approach. He emphasized the fact that although the adsorbed cations were insoluble in water, and therefore resistant to being lost by leaching, they were nevertheless available to the plant. His values for CEC ranged from 10-80 for clays to 100-200 for organic matter. Albrecht emphasized the need for a balanced soil fertility to promote healthy plants, and found it helped prevent fungus rot in onions and nematode attack in carrots (Walters, 1989).

Many of Albrecht's findings were related to soybeans, so care must be taken in their application to other species. He derived, however, a general set of ratios of basic cations and the hydrogen ion as percentages of the cation exchange capacity which would give a balanced plant nutrition: calcium, 60-75%; magnesium, 10-20% (7-15% in some plants); potassium, 2-5%; sodium, 0.5-5%; hydrogen, 10% (>10% is an acid soil); other cations (essential trace elements), 5%. He regarded these figures as guidelines applicable to humid region soil treatments for legumes, but a sound reasoning basis for the better growth of non-legumes (Albrecht, 1967). Walters (1996) says that the nutrient code for cations expressed above is being used by the important laboratories serving eco-agriculture.

Albrecht campaigned against the concept of an acid soil causing poorer crop growth; rather, it is the calcium deficiency that needs to be remedied. The acid soil solution dissolves rock particles, such as rock phosphate and limestone, to release beneficial nutrients such as phosphate and calcium respectively. It also mobilizes the other adsorbed ions off the clay-humus colloid. He estimated the optimum ratios of calcium to magnesium and calcium to potassium. These were approximately from 4:1 to 7.5:1, and from 15:1 to 38:1 respectively. The higher the Ca:K ratio, the more proteinaceous the soybean crop; the lower the ratio, the more carbonaceous, with a higher yield, but lower P and Ca. He would not recommend any other basic cation ratios, and added that the ratios should be adjusted by fertility treatments for the most efficient plant nutrition (Walters, 1989). Excesses of individual cations should be avoided to prevent harmful effects: thus excess Ca or K reduces the transport of Mg into the crop; excess Mg reduces K in the crop, and excess Ca reduces the uptake of B, Fe, K, Mn and Zn. Albrecht helped E.R. Kuck design a soil audit and inventory report for the Brookside Laboratories of Brookside Dairy Farms, New Knoxville, Ohio, USA; a facsimile is given in Walters (1996). These laboratories are still offering an analytical service and may be visited at:

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